Separations

17 pages, 3885 KiB

Open AccessArticle

Development and Validation of Liquid Chromatography-Tandem Mass Spectrometry Method for Simultaneous Determination of Tramadol and Its Phase I and II Metabolites in Human Urine

by Varsha Chauhan, Manu Sharma, Abhishek Tiwari, Varsha Tiwari, Manish Kumar, Tarun Virmani, Girish Kumar, Najla Altwaijry, Omkulthom Al kamaly, Asmaa Saleh and Abdulsalam Alhalmi

Separations 2023, 10(6), 365; https://doi.org/10.3390/separations10060365 - 19 Jun 2023

Cited by 1 | Viewed by 2075

Abstract

Tramadol (TD) has been prescribed frequently in many countries for more than 40 years, but there is a risk of its misuse and trafficking. As a result, drug analysis has numerous legal and socially relevant implications, making it an essential part of modern [...] Read more.

Tramadol (TD) has been prescribed frequently in many countries for more than 40 years, but there is a risk of its misuse and trafficking. As a result, drug analysis has numerous legal and socially relevant implications, making it an essential part of modern analytical chemistry. Thus, the method for the detection of TD and its phase I and phase II metabolites in human urine has been developed and validated using a rapid and efficient approach combining liquid chromatography-tandem mass spectrometry (LC-MS/MS) with electrospray ionization. The sample preparation was best performed using dispersive liquid–liquid microextraction. Analysis was performed using an HyPRITY Cl8 column, and isocratic elution with methanol: water (35:65) with 0.2% formic acid was used. TD and its metabolites were detected at 264.2 (TD/M0) with a base peak at 58.2, 250.3758 (M1), 250.3124 (M2), 236.3976 (M3), 222.5361 (M4), and 236.4475 (M5) m/z peaks. TD showed linearity between 0.1 and 160 ng/mL (R² = 0.9981). The accuracy ranged from 95.56 to 100.21% for the three concentration levels, while the between- and within-day RSD ranged from 1.58 to 3.92%. The absolute TD recovery was 96.29, 96.91, and 94.31% for the concentrations of 5, 50, and 150 ng/mL, respectively. TD’s phase I metabolites, M1–5 along with nine phase II metabolites, such as sulfo- and glucurono-conjugated metabolites, oxidative TD derivatives, and sulfo-conjugated metabolites were also identified in the urine samples. The pharmacokinetics and metabolism data given provide information for the design of possible future research disorders, evaluating drug mechanism and neurotoxicity and for the effective application screening of TD. Full article

(This article belongs to the Special Issue Metabolite Identification via Liquid Chromatography-Mass Spectrometry)

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19 pages, 4532 KiB

Open AccessArticle

Analysis of Pharmaceutical Processes in Chinese Medicine Based on Quantity and Measure Value Transfer: A Case of Salvia miltiorrhiza Purified Extract Preparation

by Junhui Qian, Yu Chen, Yanni Tai, Zhilong Tang, Zhenhua Wang, Kunling Guo, Xicheng Liu and Xingchu Gong

Separations 2023, 10(6), 364; https://doi.org/10.3390/separations10060364 - 18 Jun 2023

Cited by 1 | Viewed by 1353

Abstract

Quantity and measure value transfer is widely used to examine the correlation between the quality of Chinese herbs, Chinese herbal intermediates, and Chinese patent medicines. This study performed a quantity and measure value transfer analysis to assess the total solids yield, phenolic component [...] Read more.

Quantity and measure value transfer is widely used to examine the correlation between the quality of Chinese herbs, Chinese herbal intermediates, and Chinese patent medicines. This study performed a quantity and measure value transfer analysis to assess the total solids yield, phenolic component yield, and phenolic component purity in the Salvia miltiorrhiza purified extract (SMPE) preparation process. The amount of extracted total solids was between 45–250 mg/g following the processes of reflux extraction, vacuum concentration, lime–sulfuric acid refining, first ethanol precipitation, second ethanol precipitation, first acidification, alkalization, thermal hydrolysis, and second acidification. Regarding yield and purity, Danshensu ranked first among all phenolic components. Additionally, a quantitative index defined as the total variation (TV) value was proposed to describe the consistency of the SMPE preparation process. The batch-to-batch variation in the SMPE came from the variable in herb quality and the preparation process, and the latter contributed more. The contribution of individual processes to the total variation (TVP) was proposed as an index to measure the impact of processes on batch-to-batch consistency. According to the TVP value, the lime–sulfuric acid refining process, the first ethanol precipitation process, and the second acidification process were all deemed crucial. When the similarity algorithms for the composition of the intermediates and SMPE were examined, the Euclidean distance outperformed the Pearson correlation coefficient, Spearman correlation coefficient, and cosine of the pinch angles. Based on the variation in the average Euclidean distance (

Δ \bar{D_{j}}

) during the process, the second ethanol precipitation, alkalization, and thermal hydrolysis processes were determined to be critical. This study clarified the primary causes of extract quality fluctuation, identified the critical processes, and examined the pharmaceutical process of traditional Chinese medicine (TCM) from the standpoint of quantity and measure value transfer. The method can be used as a reference for the analysis of other TCM pharmaceutical processes. Full article

(This article belongs to the Section Analysis of Natural Products and Pharmaceuticals)

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18 pages, 1327 KiB

Open AccessArticle

Rapid Multi-Residue Method for Simultaneous Determination of 1,3,5-Triazine Herbicides in Environmental Samples by Capillary GC-MS-EI Selective Ion Monitoring Method

by Perumal E. Ravi, Perumal E. Thirugnanam, Jothi Ramalingam Rajabathar, Hamad Al-Lohedan, S. Jenifer and Muthusamy Karnan

Separations 2023, 10(6), 363; https://doi.org/10.3390/separations10060363 - 18 Jun 2023

Cited by 1 | Viewed by 1941

Abstract

A new multi-residue method using gas chromatography–mass spectrometry electron ionization selective ion monitoring mode (SIM) has been developed for the simultaneous determination of eight 1,3,5-triazine herbicides such as 1,3,5-triazine-2,4-diamine (atrazine), ametryn, prometryn, propazine, terbuthylazine, terbutryn, and simazine simetryn in water and soil samples. [...] Read more.

A new multi-residue method using gas chromatography–mass spectrometry electron ionization selective ion monitoring mode (SIM) has been developed for the simultaneous determination of eight 1,3,5-triazine herbicides such as 1,3,5-triazine-2,4-diamine (atrazine), ametryn, prometryn, propazine, terbuthylazine, terbutryn, and simazine simetryn in water and soil samples. Quantification is done using lindane (gamma benzene hexachloride) as an internal standard. A specific Capillary DB-Wax column of 30 m length, 0.32 mm internal diameter, and 0.25 µm film thickness is used for the separation of eight 1,3,5-triazine-2,4-diamine. The method was applied for the determination of residues in groundwater and soil samples. The lowest detection limit by GC-MS-SIM (selective ion monitoring mode) is 0.1 pg/mL. Recovery in water samples is in the range of 93–103%, and in soil samples, 91–102% for different individual compounds. Forty-five groundwater and soil samples were collected in and around Kancheepuram district in Tamilnadu (India), and they were analyzed for the respective residues. A detailed discussion of the GC-MS analysis results has been presented. Full article

(This article belongs to the Special Issue Determination of Pesticides and Drug Residues by Liquid Chromatography-Mass Spectrometry)

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16 pages, 1093 KiB

Open AccessArticle

Antimicrobial Efficacy and HPLC Analysis of Polyphenolic Compounds in a Whole-Plant Extract of Eryngium campestre

by Abdulaziz A. Al-Askar, Shimaa Bashir, Abdallah E. Mohamed, Omaima A. Sharaf, Rokaia Nabil, Yiming Su, Ahmed Abdelkhalek and Said I. Behiry

Separations 2023, 10(6), 362; https://doi.org/10.3390/separations10060362 - 18 Jun 2023

Cited by 11 | Viewed by 2637

Abstract

Due to the constant increase in the number of plant diseases and the lack of available treatments, there has been a growing interest in plant extracts over the past few decades. Numerous studies suggest that plant extract molecules possess valuable antimicrobial activities, particularly [...] Read more.

Due to the constant increase in the number of plant diseases and the lack of available treatments, there has been a growing interest in plant extracts over the past few decades. Numerous studies suggest that plant extract molecules possess valuable antimicrobial activities, particularly against fungi and bacteria. This suggests that these biomaterials could potentially serve as attractive therapeutic options for the treatment of phytopathogen infections. In the present study, we investigated and analyzed the methanolic extract of Eryngium campestre L. whole plant extract using HPLC. The analysis revealed the presence of several polyphenolic constituents, with benzoic acid, catechol, quercetin, vanillic acid, resveratrol, naringenin, and quinol being the most abundant. The amounts of these constituents were determined to be 2135.53, 626.728, 579.048, 356.489, 323.41, 153.038, and 128.77 mg/kg, respectively. Furthermore, we isolated and identified different plant fungal and bacterial isolates from symptomatic potato plants, which were accessioned as Rhizoctonia solani (OQ880458), Fusarium oxysporum (OQ820156) and Fusarium solani (OQ891085), Ralstonia solanacearum (OQ878653), Dickeya solani (OQ878655), and Pectobacterium carotovorum (OQ878656). The antifungal activity of the extract was assessed using fungal growth inhibitions (FGI) at concentrations of 100, 200, and 300 µg/mL. The results showed that at the lowest concentration tested (100 µg/mL), the extract exhibited the highest effectiveness against R. solani with an FGI of 78.52%, while it was least effective against F. solani with an FGI of 61.85%. At the highest concentration tested, the extract demonstrated the highest effectiveness against R. solani and F. oxysporum, with FGIs of 88.89% and 77.04%, respectively. Additionally, the extract displayed a concentration-dependent inhibitory effect on all three bacterial pathogens. At the highest concentration tested (3000 µg/mL), the extract was able to inhibit the growth of all three bacterial pathogens, although the inhibition zone diameter varied. Among the bacterial pathogens, D. solani exhibited the highest sensitivity to the extract, as it showed the largest inhibition zone diameter at most of the extract concentrations. These findings highlight the potential of the E. campestre extract as a source of natural antimicrobial agents for controlling various plant pathogens. Consequently, it offers a safer alternative to the currently employed protective methods for plant disease management. Full article

(This article belongs to the Special Issue Application of Hyphenated Techniques in Natural Product Analysis)

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11 pages, 626 KiB

Open AccessArticle

Phytotoxicity of Rich Oxygenated Terpenes Essential Oil of Prosopis farcta against the Weed Dactyloctenium aegyptium

by Ahmed M. Abd-ElGawad, Abdulaziz M. Assaeed, Abd El-Nasser El Gendy, Luisa Pistelli, Basharat A. Dar and Abdelsamed I. Elshamy

Separations 2023, 10(6), 361; https://doi.org/10.3390/separations10060361 - 18 Jun 2023

Cited by 1 | Viewed by 1752

Abstract

Weeds are considered the main reason for crop yield loss in the world. Weed control and management include various treatments such as cultural, physical, chemical, and biological methods. Chemical control of weeds is the most common method; however, the application of commercial synthetic [...] Read more.

Weeds are considered the main reason for crop yield loss in the world. Weed control and management include various treatments such as cultural, physical, chemical, and biological methods. Chemical control of weeds is the most common method; however, the application of commercial synthetic herbicides caused several dangerous hazards in the environment including the appearance of resistant weed biotypes. Prosopis farcta (Banks & Sol.) J.F.Macbr. (Family: Fabaceae), is a common weed plant in the Middle East, where it is hard to eliminate due to its deep and overlapped roots. On the other side, it has many traditional uses around the world. Herein, the essential oil (EO) of P. farcta above-ground parts was extracted via hydrodistillation techniques and then analyzed using gas chromatography-mass spectroscopy (GC-MS). From the GC-MS analysis, 47 compounds were identified with a relative concentration of 98.02%, including terpenes as the main components (95.08%). From overall identified compounds, cubenol (19.07%), trans-chrysanthenyl acetate (17.69%), torreyol (8.28%), davana ether (3.50%), camphor (3.35%), and farnesyl acetone (3.13%) represented the abundant constituents. Furthermore, the phytotoxic activity of the P. farcta EO was assessed against the weed Dactyloctenium aegyptium (L.) Willd. The EO of P. farcta, at a concentration of 100 µL L⁻¹, significantly inhibited the germination, seedling shoot growth, and seedling root growth by 64.1, 64.0, and 73.4%, respectively. The results exhibited that the seedling root growth is the most affected followed by the seed germination and seedling shoot growth with respective IC₅₀ at 64.5, 80.5, and 92.9 µL L⁻¹. It can be concluded that weeds are not absolutely harmful, but they may have beneficial uses, such as, for example as a source of phytochemicals with application in weed control practices (bioherbicides). It is advised to conduct additional research to characterize the allelopathic action of the major chemicals in their pure form, either alone or in combination, against a variety of weeds. Full article

(This article belongs to the Special Issue Application of Separation and/or Purification Technology in Natural Products, Newly Synthetic Candidates, and Pharmaceuticals)

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16 pages, 7807 KiB

Open AccessArticle

Isolation and Identification of Flavonoids from Black Cumin (Nigella sativa) by HPLC-MS and In Silico Molecular Interactions of Their Major Compounds with Fusarium oxysporum Trypsin-like Serine Protease

by Hossam S. El-Beltagi, Seham M. S. Abdel Aziz, A. I. Aboshady, Mervat A. R. Ibrahim, Mohamed F. M. Ibrahim, Muneefah Abdullah Alenezi, Doaa Bahaa Eldin Darwish, Salem Mesfir Al-Qahtani, Nadi Awad Al-Harbi, Hadeer Darwish and Hany A. M. Srour

Separations 2023, 10(6), 360; https://doi.org/10.3390/separations10060360 - 17 Jun 2023

Cited by 5 | Viewed by 1804

Abstract

Fusarium oxysporum is one of the most harmful soil-borne pathogens that cause root rot, damping-off, and wilt disease in many plant species. Management of Fusarium oxysporum diseases is often by using many harmful and expensive chemical fungicides which have many harmful effects on [...] Read more.

Fusarium oxysporum is one of the most harmful soil-borne pathogens that cause root rot, damping-off, and wilt disease in many plant species. Management of Fusarium oxysporum diseases is often by using many harmful and expensive chemical fungicides which have many harmful effects on the environment and human health. The current study was conducted to identify the chemical constituents of black cumin seeds’ methanolic extract and investigate the ability of the major constituents to inhibit the Fusarium oxysporum trypsin-like serine protease, which play an important role in F. oxysporun pathogenicity. The HPLC-MS analysis of black cumin seeds’ methanolic extract revealed the presence of seven major compounds: amentoflavone, Procyanidin C2, Quercetin3-O-sophoroside-7-O-rhamnoside, 5,7-Dihydroxy-3,4-dimethoxyflavone, Borapetoside A, tetrahydroxy-urs-12-en-28-O-[b-D-glucopyranosyl (1-2)-b-D-glucopyranosyl] ester, and kudzusapongenol A-hexA-pen. The results of molecular docking between these compounds and the active site of Fusarium oxysporium trypsin showed that only four compounds were able to bind to the active site of F. oxysporum trypsin. Amentoflavone, 5,7-Dihydroxy-3,4-dimethoxyflavone, and Quercetin3-O-sophoroside-7-O-rhamnoside have the highest binding energy, −6.4, −6.5, and −6.5 Kcal/mol, respectively. In addition, the results clarify that 5,7-Dihydroxy-3,4-dimethoxyflavone was the only compound to form a hydrogen bond with Asp189 (the residue responsible for substrate specificity). The results of the study strongly indicate that flavonoids of black cumin seeds’ methanolic extract could be used as effective inhibitors for the F. oxysporum trypsin-like serine protease. Full article

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12 pages, 840 KiB

Open AccessArticle

A Sensitive, Simple, and Fast LC–MS/MS Method for Quantification of Remifentanil in Human Plasma: Applications in Critically Ill Patients’ Plasma during Extracorporeal Membrane Oxygenation

by Soon Uk Chae, Ji Seon Kim, Chae Bin Lee, Seong Jun Jo, Kyung Lok Min, Min Jung Chang and Soo Kyung Bae

Separations 2023, 10(6), 359; https://doi.org/10.3390/separations10060359 - 15 Jun 2023

Viewed by 1537

Abstract

A sensitive, simple, and fast liquid chromatography–tandem mass spectrometry (LC–MS/MS) bioanalytical method was developed to determine remifentanil in human plasma and prevent its instability by esterases during quantification. A 20 μL sample of human plasma, acidified with formic acid, was precipitated using 100 [...] Read more.

A sensitive, simple, and fast liquid chromatography–tandem mass spectrometry (LC–MS/MS) bioanalytical method was developed to determine remifentanil in human plasma and prevent its instability by esterases during quantification. A 20 μL sample of human plasma, acidified with formic acid, was precipitated using 100 μL of acetonitrile. Chromatography was carried out on an Agilent Poroshell 120 EC-C18 column (4.6 × 50 mm, 2.7 μm) with an isocratic elution by acetonitrile and distilled water containing 0.1% formic acid (65:35, v/v) at a flow rate of 0.5 mL/min. Transition ions were detected as m/z 377.10→113.20 and m/z 277.00→111.00 for remifentanil and chlorpropamide (internal standard), respectively, with positive electrospray ionization in mass spectrometry. The run time was only 3 min per sample. We evaluated the selectivity, linearity, carry-over, accuracy, precision, extraction recovery, absolute matrix effect, stability, and incurred sample reanalysis and found that all these parameters were within acceptable limits. The calibration curve range for remifentanil was 0.05–50 ng/mL with regression coefficient (r) values higher than 0.9939. Given the simple and fast sample preparation and the lower LLOQ concentration compared to those in other methods, this method was successfully used to quantify plasma levels after intravenous infusion of remifentanil to intensive-care-unit patients during extracorporeal membrane oxygenation. Full article

(This article belongs to the Section Bioanalysis/Clinical Analysis)

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21 pages, 4481 KiB

Open AccessArticle

Application of a Novel Bifunctionalized Magnetic Biochar to Remove Cr(VI) from Wastewater: Performance and Mechanism

by Xiangfen Cui, Juan Wang, Qun Zhao, Chen Li, Jianhong Huang, Xuewei Hu, Jie Li and Mantao Li

Separations 2023, 10(6), 358; https://doi.org/10.3390/separations10060358 - 15 Jun 2023

Cited by 5 | Viewed by 1571

Abstract

Biochar adsorption has emerged as a favorable and environmentally friendly approach for removing metals such as chromium (Cr) from wastewater. However, the use of pristine biochar (PBC) is limited due to its finite adsorptive capacity, selectivity, and potential for secondary pollution. In this [...] Read more.

Biochar adsorption has emerged as a favorable and environmentally friendly approach for removing metals such as chromium (Cr) from wastewater. However, the use of pristine biochar (PBC) is limited due to its finite adsorptive capacity, selectivity, and potential for secondary pollution. In this study, a novel bifunctionalized magnetic biochar (BMBC) was fabricated by incorporating cystamine as a ligand and glutaraldehyde as a crosslinker into alkali-treated magnetic biochar (MBC). This chemical modification introduced numerous amino groups and disulfide bonds onto the surfaces of BMBC. The biochar adsorbents’ surface morphologies, crystal structures, and texture properties were characterized using SEM, XRD, and N₂ adsorption-desorption techniques. The specific surface area was determined using the BET method. Furthermore, the surface functional groups and elemental compositions before and after adsorption were analyzed using FTIR and XPS, respectively. The results demonstrated higher Cr(VI) removal efficacy of BMBC (100%) than MBC (72.37%) and PBC (61.42%). Optimal conditions for Cr(VI) removal were observed at a solution pH of 2, a temperature of 50 °C, a reaction time of around 1440 min, and an initial adsorbate concentration of 300 mg/L. The sorption process followed a chemical mechanism and was controlled by monolayer adsorption, with a maximum adsorption capacity of 66.10 mg/g at 50 °C and a pH of 2, as indicated by the larger fitting values of the pseudo–second-order and Langmuir models. The positive ∆H^o and ∆S^o values and negative ∆G0 values suggested a spontaneous and endothermic Cr(VI) adsorption process with high randomness at the solid/liquid interface. The removal of Cr(VI) was attributed to the reduction of Cr(VI) into Cr(III) facilitated by the introduced amino acids, sulfur, and Fe(II), electrostatic interaction between Cr(VI) in the solution and positive charges on the adsorbent surface, and complexation with functional groups. The presence of co-existing cations such as Cu(II), Cd(II), Mn(II), and K(I) had little effect on Cr(VI) removal efficiency. At the same time, the co-existence of anions of Cl⁻, NO₃⁻, SO₄²⁻, and HPO₄²⁻ resulted in a 7.58% decrease in the Cr(VI) removal rate. After five consecutive adsorption/desorption cycles, BMBC maintained a high Cr(VI) removal rate of 61.12%. Overall, this novel BMBC derived from rice straw shows great promise as a biosorbent for treating Cr(VI) in wastewater. Full article

(This article belongs to the Special Issue (Bio)-Sorbents for Water Treatment and Soil Remediation)

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11 pages, 1843 KiB

Open AccessCommunication

Simple Preparation of a Unique Ionic Liquid/Deep Eutectic Solvent and β-Cyclodextrin Composite Discs and Its Use to Capture Hazardous Substances from Water

by Yingying Guo, Na Liu, Hangping Chen, Ahmad Ali, Sara Toufouki and Shun Yao

Separations 2023, 10(6), 357; https://doi.org/10.3390/separations10060357 - 15 Jun 2023

Viewed by 1485

Abstract

With the development of health service, animal husbandry, aquaculture and the chemical industry, more and more pollutants are discharged into the water environment, including antibiotics and heavy-metal ions. These hazardous substances pose a great threat to environmental safety and human health. Two new [...] Read more.

With the development of health service, animal husbandry, aquaculture and the chemical industry, more and more pollutants are discharged into the water environment, including antibiotics and heavy-metal ions. These hazardous substances pose a great threat to environmental safety and human health. Two new kinds of green solvents, ionic liquids (ILs) and deep eutectic solvents (DESs), are widely utilized in various fields, including separation and environmental engineering, and are attracting much attention from academia and industry. In this study, an optimal ionic liquid and a deep eutectic solvent were selected, and their complex with β-cyclodextrin (β-CD) was first prepared by a process of simple and effective inclusion. After necessary characterization and analysis, two kinds of complexes were applied to prepare a special two-sided sorbent disc by adding a diluent (excipient) and pressing the substance under 5~15 MPa. As a result, the IL and DES were stably immobilized on the disc to play a key role in the selective adsorption of targets. Moreover, the experiments with different hazardous substances achieved the expected results. This study demonstrates that the complex disc, with its easy preparation, good stability, and simple operation, exhibited many merits in its separation performance. We believe it to be a useful tool for water purification and detection of noxious substances. Full article

(This article belongs to the Section Purification Technology)

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19 pages, 7218 KiB

Open AccessArticle

Study on the Effects of Wet Flue Gas Desulfurization on Particulate Matter Emission from Industrial Coal-Fired Power Plants

by Anyu Wang, Shuran Li, Qinzhen Zheng, Shuo Zhang, Shihao Zhang, Zhihao Wang, Zhen Liu and Keping Yan

Separations 2023, 10(6), 356; https://doi.org/10.3390/separations10060356 - 14 Jun 2023

Cited by 4 | Viewed by 2182

Abstract

This study aimed to investigate the effects of wet flue gas desulfurization (WFGD) on particulate matter (PM) emissions in coal-fired power plants (CFPPs) using an electrical low-pressure impactor (ELPI). The investigation was conducted on five industrial CFPPs of various loads in China to [...] Read more.

This study aimed to investigate the effects of wet flue gas desulfurization (WFGD) on particulate matter (PM) emissions in coal-fired power plants (CFPPs) using an electrical low-pressure impactor (ELPI). The investigation was conducted on five industrial CFPPs of various loads in China to clarify the influence factors of WFGD on PM₁₀ emissions. After WFGD, the proportion of PM_2.5 to PM₁₀ in the outlet flue gas increases, which showed that the WFGD system is selective in the capture of PM, with a significant effect on the capture of large particle sizes. The investigation found that four spray layers have a better effect on the capture of particles than two spray layers. Additionally, the investigation also found that unit load is not the main factor affecting the efficiency of PM₁₀ capture by WFGD. Instead, the factors affecting the capture efficiency of PM₁₀ by WFGD are the inlet flue gas temperature and the dust concentration. Relatively higher inlet flue gas temperature and lower inlet dust concentration will both result in higher emission of PM_0.1~1 from the WFGD outlet. These findings suggest that a matched integration of WFGD and CFPP is essential for ultra-low PM emission control and green industry development. Full article

(This article belongs to the Topic Research on Electrostatic Precipitation)

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12 pages, 3526 KiB

Open AccessArticle

Improved Palladium Extraction from Spent Catalyst Using Ultrasound-Assisted Leaching and Sulfuric Acid–Sodium Chloride System

by Jinjiao Wang, Xiaoping Zhu, Jiale Fan, Ke Xue, Shengyu Ma, Ruiming Zhao, Hao Wu and Qin Gao

Separations 2023, 10(6), 355; https://doi.org/10.3390/separations10060355 - 13 Jun 2023

Cited by 2 | Viewed by 2040

Abstract

This paper presents a process for efficiently recovering palladium (Pd) from spent Pd/Al₂O₃ catalysts used for hydrogenation reactions, using ultrasound-assisted leaching (UAL). A system composed of H₂SO₄ and NaCl was investigated under ultrasound-enhanced conditions and compared to [...] Read more.

This paper presents a process for efficiently recovering palladium (Pd) from spent Pd/Al₂O₃ catalysts used for hydrogenation reactions, using ultrasound-assisted leaching (UAL). A system composed of H₂SO₄ and NaCl was investigated under ultrasound-enhanced conditions and compared to regular leaching methods to demonstrate the superiority of UAL. Single-factor experiments were conducted to determine the optimal conditions for leaching, which included an ultrasound power of 200 W, a liquid–solid ratio of 5:1, a leaching time of 1 h, a leaching temperature of 60 °C, H₂SO₄ concentration of 60%, and 0.1 mol of NaCl. The leaching rate under these conditions was found to be 99%. Additionally, kinetic analysis of the UAL process showed that the apparent activation energy of the Pd leaching reaction was 28.7 kJ/mol, and it was found that Pd leaching from spent catalysts was controlled by diffusion. The tailings were analyzed by SEM, revealing that during ultrasonic leaching, the specific surface area of the spent catalyst increased, the mass transfer rate of the solution was accelerated, the passivation film on the surface of the spent catalyst was peeled off, and a new reaction interface was formed. This improved the leaching rate of Pd and provided a new approach to efficiently leach precious metals such as Pd from spent catalysts. Full article

(This article belongs to the Special Issue Separation and Extraction of Solid Waste Resources)

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17 pages, 1837 KiB

Open AccessEditor’s ChoiceArticle

Comprehensive Metabolite Fingerprinting of Australian Black and Green Olives and Their Antioxidant and Pharmacokinetics Properties

by Akhtar Ali, Farhad Ahmadi, Jeremy J. Cottrell and Frank R. Dunshea

Separations 2023, 10(6), 354; https://doi.org/10.3390/separations10060354 - 13 Jun 2023

Cited by 6 | Viewed by 2518

Abstract

Polyphenols, especially flavonoids, are well-known for their bioactive antioxidant properties. Therefore, this study aimed to analyze Australian black (ripe) and green olives (unripe) for phenolic and non-phenolic metabolites, antioxidant activities, and pharmacokinetic properties. Liquid chromatography–mass spectrometry coupled with quadrupole–time of flight (LC–ESI–QTOF–MS/MS) was [...] Read more.

Polyphenols, especially flavonoids, are well-known for their bioactive antioxidant properties. Therefore, this study aimed to analyze Australian black (ripe) and green olives (unripe) for phenolic and non-phenolic metabolites, antioxidant activities, and pharmacokinetic properties. Liquid chromatography–mass spectrometry coupled with quadrupole–time of flight (LC–ESI–QTOF–MS/MS) was applied to elucidate the composition, identification, and characterization of bioactive metabolites from Australian olives. This study identified 110 metabolites, including phenolic acids, flavonoids, stilbenes, lignans, and other compounds (phenolic terpenes, tyrosols, fatty acids, and terpenoids). Luteolin (flavonoid) and verbascoside (hydroxycinnamic acid) are identified with higher concentrations in black olives. Black (ripe) olives were measured at a higher TPC (10.94 ± 0.42 mg GAE/g) and total antioxidant potential than green olives. The pharmacokinetic properties (absorption, distribution, metabolism, excretion, toxicity) of phenolic compounds for human health were evaluated to predict the potential of the most abundant metabolites in olives. Gastrointestinal absorption and Caco-2 cell permeability of metabolites in olives were also predicted. This study will develop into further research to identify the Australian olives’ therapeutic, nutraceutical, and phytopharmaceutical potential. Full article

(This article belongs to the Special Issue Isolation, Elucidation and Synthesis of Bioactive Natural Products)

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16 pages, 6905 KiB

Open AccessArticle

In Vitro and Reactive Metabolites Investigation of Metabolic Profiling of Tyrosine Kinase Inhibitors Dubermatinib in HLMs by LC–MS/MS

by Nasser S. Al-Shakliah, Adnan A. Kadi, Hatem A. Abuelizz and Rashad Al-Salahi

Separations 2023, 10(6), 353; https://doi.org/10.3390/separations10060353 - 13 Jun 2023

Viewed by 1723

Abstract

Dubermatinib (DMB, TP-0903), a benzenesulfonamide, is an inhibitor of the tyrosine kinase AXL, which is a member of the TAM family and can prevent GAS6-mediated activation of AXL in cancer cells. Patients with previously treated chronic lymphocytic leukemia are being studied in phase [...] Read more.

Dubermatinib (DMB, TP-0903), a benzenesulfonamide, is an inhibitor of the tyrosine kinase AXL, which is a member of the TAM family and can prevent GAS6-mediated activation of AXL in cancer cells. Patients with previously treated chronic lymphocytic leukemia are being studied in phase I/II clinical trials to determine its antineoplastic potential (CLL). In the current work, the Xenosite web predictor tool was employed to predict the vulnerable sites of metabolism and the reactivity pathways (cyanide and GSH) of DMB. Subsequently, we present the analysis and identification of in vitro and reactive intermediates of DMB using liquid chromatography ion trap mass spectrometry (LC–ITMS). Human liver microsomes (HLMs) were exposed to dimethylbenzene in a laboratory setting, and the resulting metabolites were collected through protein precipitation. Intense reactivity toward nucleophilic macromolecules was seen in the metabolites of the piperazine and pyrimidine rings in DMB, iminium, and 2,5-quinone-imine, respectively. To assess the toxicities of the possibly reactive metabolites, DMB was incubated with HLMs in the presence of 1.0 mM KCN and 1.0 mM glutathione. The DMB metabolites found by LC–MS/MS were seven in vitro phase I metabolites, three cyano adducts, and two GSH conjugates. Phase I in vitro metabolic reactions included N-demethylation, hydroxylation, and dechlorination. DMB and its metabolites have not been investigated for their metabolism in vitro. Full article

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21 pages, 6229 KiB

Open AccessFeature PaperArticle

Synthesis and Characterization of Amorphous SiO₂−Fe_xO_y Materials Starting from Iron Sulfate for Preliminary Studies of CO₂ Adsorption

by Cătălin Ianăşi, Bogdan Pascu, Nicoleta Nemeş and Alexandru Popa

Separations 2023, 10(6), 352; https://doi.org/10.3390/separations10060352 - 13 Jun 2023

Cited by 1 | Viewed by 1789

Abstract

The goal of this work is to investigate the effectiveness of amorphous SiO₂−Fe_xO_y loaded by functionalization with Ce(SO₄)₂, Li₂SO₄, and 3-aminopropyltriethoxysilane (APTES) for CO₂ adsorption. Silica and iron-based materials [...] Read more.

The goal of this work is to investigate the effectiveness of amorphous SiO₂−Fe_xO_y loaded by functionalization with Ce(SO₄)₂, Li₂SO₄, and 3-aminopropyltriethoxysilane (APTES) for CO₂ adsorption. Silica and iron-based materials are gaining popularity due to their wide range of applications, such as catalysis, photocatalysis, imaging, etc.; however, there are very few studies regarding the adsorption of CO₂ with the aforementioned materials. In our study, we proposed to test their ability in this direction by adding cerium sulfate and lithium sulfate. Three base materials were obtained and characterized using XRD, FTIR, RAMAN, TG, SEM, and BET followed by their functionalization with amino groups by using of the APTES precursor. The SEM images indicate an increase in size, forming clusters from 100 nm for base materials to 500 nm for functionalized materials. The results indicate a maximum CO₂ adsorption of 1.58 mmol/g material for the SiO₂−Fe_xO_y−Li−APTES sample. Full article

(This article belongs to the Special Issue Advances in CO₂ Adsorptive Separation for CO₂ Capture)

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31 pages, 3117 KiB

Open AccessReview

Sensitivity Enhancement for Separation-Based Analytical Techniques Utilizing Solid-Phase Enrichment Approaches and Analyte Derivatization for Trace Analysis in Various Matrices

by Hanan Farouk, Hager Ebrahim, Heba Sonbol, Monika Malak, Maha Kamal, Noha Ibrahim, Ahmed Shawky, Walaa Zarad, Ahmed Emad and Samy Emara

Separations 2023, 10(6), 351; https://doi.org/10.3390/separations10060351 - 13 Jun 2023

Cited by 2 | Viewed by 2579

Abstract

Despite the fact that strong routine separation methodologies can give reliable specificity and validity at usual working pharmaceutical concentrations, they may fail at very low concentration levels. This poses considerable challenges for researchers investigating product purity and therapeutic drug monitoring. Sensitivity enhancement procedures [...] Read more.

Despite the fact that strong routine separation methodologies can give reliable specificity and validity at usual working pharmaceutical concentrations, they may fail at very low concentration levels. This poses considerable challenges for researchers investigating product purity and therapeutic drug monitoring. Sensitivity enhancement procedures are thus required to maximize the performance of separation techniques. Solid-phase extraction/solid-phase enrichment (SPE/SPEn) and pre-, post-, and in-column derivatization, as well as the use of sensitive detection devices, are the simplest strategies for improving sensitivity of separation-based analytical techniques. Large-volume injection of samples with online SPE/SPEn coupled with separation techniques increased sensitivity and improved detection as well as quantification limits without affecting peak shape and system performance. Although the primary purpose of derivatization is to improve sensitivity and selectivity, greener derivatization is growing in popularity and should be considered in analytical chemistry. In general, two strategies are essential for accomplishing greener derivatization goals. The first is the search for and use of ecologically acceptable derivatizing reagents, solvents, and reaction conditions. The second is miniaturization and automation of analytical methods. This review discusses significant advances in separation-based analytical techniques, specifically enrichment approaches and detector signal improvement for pharmaceutical quantification in various matrices at very low concentration levels. As a result of improved analytical systems setup in drug assays, the possibility of high-throughput analyses was also highlighted. Full article

(This article belongs to the Section Analysis of Natural Products and Pharmaceuticals)

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13 pages, 1495 KiB

Open AccessArticle

Programmable Low-Pressure Chromatographic Sub-90 s Assay of Parabens in Cosmetics with Post-Column Chemiluminescence Detection

by Margarita Barbatsi and Anastasios Economou

Separations 2023, 10(6), 350; https://doi.org/10.3390/separations10060350 - 11 Jun 2023

Cited by 1 | Viewed by 1468

Abstract

This work describes a new programmable low-pressure chromatography method with post-column chemiluminescence (CL) detection for the rapid and cost-effective determination of four parabens in cosmetic products. Elution of the target analytes was achieved using a programmable mobile phase prepared by implementing a linear [...] Read more.

This work describes a new programmable low-pressure chromatography method with post-column chemiluminescence (CL) detection for the rapid and cost-effective determination of four parabens in cosmetic products. Elution of the target analytes was achieved using a programmable mobile phase prepared by implementing a linear solvent gradient protocol based on appropriate flow rate modulation of 2 MilliGAT pumps. A 5 mm monolithic C18 column was used to separate the parabens. Post-column reaction of the eluted parabens with an acidic Ce(IV)-rhodamine 6G (Rho 6G) medium was carried out by introducing a flow stream of the reactants into the column eluate. The light generated from the CL reaction was detected with a flow-through CL detector fabricated in-house. The whole sequence of operations (including sample injection, generation of the mobile phase, addition of the post-column reaction reagents and signal acquisition) was under full computer control. Various operational parameters (the mobile phase composition and gradient conditions, the CL reagents’ concentrations and flow rates and the length of the reaction coil) were studied. The method was validated and applied to the analysis of various cosmetic products. The proposed approach allows sub-90 s separation of the four parabens and their determination with a limit of quantification of 0.2 μg L⁻¹ with a sample throughput of 24 samples h⁻¹. In addition, the method is economical, makes use of low-cost low-pressure components, is fully automated and produces a low amount of waste. Full article

(This article belongs to the Collection Recent Trends in the Separation of Natural Products and Pharmaceuticals)

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22 pages, 6162 KiB

Open AccessFeature PaperArticle

Assessment of Two Materials as Adsorbents for the Effective Removal and Further Pre-Concentration of Gallium from Aqueous Solutions: Mesoporous Carbon vs. Clinoptilolite

by Patricia Sáez, Ignacio Bernabé, José Mª. Gómez, Eduardo Díez, Cristina Fraile, Noelia García and Araceli Rodríguez

Separations 2023, 10(6), 349; https://doi.org/10.3390/separations10060349 - 9 Jun 2023

Cited by 2 | Viewed by 1484

Abstract

In this research, the adsorption of gallium onto natural zeolite (clinoptilolite) and two mesoporous-activated carbons were compared and evaluated. The clinoptilolite was treated with HCl (HCPL), while mesoporous-activated carbons (MCSG60A and MCO1) were synthesized by replica method, using sucrose as the carbon precursor [...] Read more.

In this research, the adsorption of gallium onto natural zeolite (clinoptilolite) and two mesoporous-activated carbons were compared and evaluated. The clinoptilolite was treated with HCl (HCPL), while mesoporous-activated carbons (MCSG60A and MCO1) were synthesized by replica method, using sucrose as the carbon precursor and silica gel as the template. These carbonaceous materials showed large pore sizes and mesoporous surface, as well as a suitable surface chemistry for cation adsorption, which promotes a high negative charge density. On the other hand, zeolites have narrower pore sizes, which hinders the material diffusion inside the particle; however, its strength is their ion exchange capacity. Regarding the gallium kinetic studies, it is described by Pseudo-second order model for both sorts of adsorbents. MCO1 is the best carbonaceous adsorbent studied, with a capacity of 4.58 mg/g. As for zeolites, between the two zeolites studied, HCPL showed the best results, with a gallium adsorption capacity of 3.1 mg/g. The gallium adsorption mechanism onto MCO1 material is based on physisorption, while HCPL is mainly retained due to an ion-exchange process. Regarding the Giles classification, MCO1 isotherm described an H-4 pattern of high affinity and characteristic of multilayer adsorption. The Double-Langmuir model fits properly within these experimental results. In the case of zeolites, HCPL adsorption isotherm followed an L-2 pattern, typical of monolayer adsorption—the Sips model is the one that better describes the adsorption of gallium onto the zeolite. Full article

(This article belongs to the Special Issue Development of Mesoporous Materials for Adsorption and Recovery of Metals)

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15 pages, 3894 KiB

Open AccessArticle

Chemical Characterization, Antioxidant, Insecticidal and Anti-Cholinesterase Activity of Essential Oils Extracted from Cinnamomum verum L.

by Ghada Beniaich, Otmane Zouirech, Aimad Allali, Mohammed Bouslamti, Imane Maliki, Abdelfattah El Moussaoui, Mohamed Chebaibi, Hiba-Allah Nafidi, Yousef A. Bin Jardan, Mohammed Bourhia and Mustapha Taleb

Separations 2023, 10(6), 348; https://doi.org/10.3390/separations10060348 - 9 Jun 2023

Cited by 4 | Viewed by 2075

Abstract

This study is aimed at evaluating the potential of the essential oil of Cinnamomum verum (EOCV) as an antioxidant, as an insecticide against Callosobruchus maculatus and for its anti-acetylcholinesterase activity. To this end, EOCV was extracted via hydrodistillation from this plant, and the [...] Read more.

This study is aimed at evaluating the potential of the essential oil of Cinnamomum verum (EOCV) as an antioxidant, as an insecticide against Callosobruchus maculatus and for its anti-acetylcholinesterase activity. To this end, EOCV was extracted via hydrodistillation from this plant, and the identification of the phytochemicals was performed using gas chromatography–mass spectrometry (GC–MS). The antioxidant power was determined via in vitro tests, the insecticidal ability was tested via exposing C. maculatus to EOCV, and molecular docking was used to evaluate the anti-cholinesterase ability. The results of these GC–MS analyses show that the main composition of EOCV comprises Cinnamaldehyde dimethyl acetal (64.50%), cinnamicaldehyde (35.04%) and α-Copaene (0.11%). The insecticidal potential of the studied OEs, determined by using the inhalation test, and expressed as the concentration of EOs required for the death of 50% of the insects (LC50) and that required the death of 95% of adults (LC95) after 96 h of exposure, was 3.99 ± 0.40 and 14.91 ± 0.10 μL/L of air, respectively. In the contact test, 96 h of exposure gave an LC50 and LC95 of 3.17 ± 0.28 and 8.09 ± 0.05 μL/L of air, respectively. A comparison of the antioxidant activity of EOCV to that of ascorbic acid via DPPH free radical scavenging ability and Ferric Reducing Antioxidant Power (FRAP) revealed the IC50 and EC50 values of EOCV to be much higher than that obtained for ascorbic acid, and the molecular docking simulation revealed Coumarin, Piperonal, Cinnamaldehyde dimethyl and alpha-Copaene as possessing potential inhibitory activities against human acetylcholinesterase. However, further experimental validation is needed to enhance the prospects of this study. Full article

(This article belongs to the Special Issue Essential Oils: Extraction, Chemical Composition, and Biological Activity)

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18 pages, 1391 KiB

Open AccessArticle

Chemometric Approach for Profiling of Metabolites of Potential Antioxidant Activity in Apiaceae Species Based on LC-PDA-ESI-MS/MS and FT-NIR

by Noha H. Atta, Heba Handoussa, Iris Klaiber, Bernd Hitzmann and Rasha S. Hanafi

Separations 2023, 10(6), 347; https://doi.org/10.3390/separations10060347 - 8 Jun 2023

Cited by 1 | Viewed by 1601

Abstract

Chemometrics is a tool for data mining and unlocking the door for solving big data queries. Apiaceae is a family species which is commonly cultivated worldwide. Although members of this species are widely used as antioxidant, antibacterial, antifungal, and anti-inflammatory agents, their metabolites [...] Read more.

Chemometrics is a tool for data mining and unlocking the door for solving big data queries. Apiaceae is a family species which is commonly cultivated worldwide. Although members of this species are widely used as antioxidant, antibacterial, antifungal, and anti-inflammatory agents, their metabolites profiling remains ambiguous. Based on WHO support, chemometrics has been used in evaluating the quality and authenticity of the herbal products. The objective of this study is to profile and characterize phenolic metabolites in nine species from Egyptian cultivars and three different species of German cultivars from the Apiaceae family using multivariate analysis after LC-PDA-ESI-MS/MS and near infrared spectroscopy data are generated. Principal component analysis was successfully applied to distinguish between the nine Egyptian cultivars and the three German cultivars, and hierarchical cluster analysis also confirmed this distinctive clustering. Partial least square regression (PLS-R) models showed a relationship between phytochemicals and antioxidant activities. The metabolites responsible for the clustering pattern and variables important for projection (VIP) were identified, being twelve amongst nine Egyptian cultivar samples and thirteen amongst the Egyptian cultivar and the German cultivar comparison. The identified VIPs were also correlated with the antioxidant activity using PLS-R. In conclusion, the study showed novelty in the application of hyphenated analytical techniques and chemometrics that assist in quality control of herbal medicine. Full article

(This article belongs to the Special Issue Application of Hyphenated Techniques in Bioanalysis and Metabolite Identification)

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17 pages, 3238 KiB

Open AccessArticle

Optimization of Chromatographic Conditions with QbD for Method Development and Validation of Bosutinib by HPLC: Applications in Dosage Forms and Rat Plasma Analysis

by Asim Najmi, Zia ur Rehman, Hassan Ahmed Alhazmi, Mohammed Mofarreh Albratty, Nasser Hassan Majrashi, Khalid Mohammed Hakami, Naif Ali Najmi and Ammar Abdullah Mobarki

Separations 2023, 10(6), 346; https://doi.org/10.3390/separations10060346 - 7 Jun 2023

Cited by 3 | Viewed by 3099

Abstract

Aim: Bosutinib (BST) is an anti-cancer medicine that is used to treat a variety of different types of cancer. Using the HPLC method of analysis and the Quality by Design (QbD) strategy, the study aimed to precisely quantify the drug in tablet form [...] Read more.

Aim: Bosutinib (BST) is an anti-cancer medicine that is used to treat a variety of different types of cancer. Using the HPLC method of analysis and the Quality by Design (QbD) strategy, the study aimed to precisely quantify the drug in tablet form and in rat plasma. Methodology: For the developed method’s validation, the chromatographic settings were fine-tuned by making use of the Box–Behnken Design (BBD). In the BBD, two dependent variables and three independent variables were selected. Isocratically, samples were eluted, having eluent phase composition of ammonium acetate (CH₃COONH₄) buffer pH 3.0 and acetonitrile (CH₃CN) (60:40% v/v), in Raptor C-18 column at temperature 25

^{\circ}

C with a flow rate of 1 mL/min for 5 min. The wavelength of detection was set at 260 nm. In this study, encorafenib (ENC) was employed as an internal standard. Result: A sharp and resolved peak of BST and ENC at a retention time of 1.92 min and 4.01 min, respectively, was observed by the developed method. The limits of quantification and detection of the newly established method were found to be 1.503

μ

g/mL⁻¹ and 0.496

μ

g/mL⁻¹. The calibration curve’s observed linearity range was between 2 and 20

μ

g/mL⁻¹, with an r² of 0.999. The developed and optimized method was verified in compliance with the ICH guidelines. The results of all validation parameters were within the acceptable range, for example, % RSD of system suitability (0.63–4.46), % RSD of linear regression (1.659), interday and intraday precision % RSD value (1.723–1.892), and (1.762–1.923), respectively, and accuracy (1.476–1.982). Conclusion: The quantity of BST in tablet dosage form and in rat plasma samples was determined using a simple, quick, and robust method that was devised and validated. Full article

(This article belongs to the Special Issue Sensitivity Enhancement Approaches to the Separation Techniques for Pharmaceutical Analysis and Therapeutic Drug Monitoring)

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17 pages, 1070 KiB

Open AccessEditor’s ChoiceArticle

Particle Cut Diameter Prediction of Uniflow Cyclone Systems with Fuzzy System Analysis

by Vinzenz Klapper, Giovanni Luzi, Benedict Prah and Antonio Delgado

Separations 2023, 10(6), 345; https://doi.org/10.3390/separations10060345 - 5 Jun 2023

Cited by 1 | Viewed by 2726

Abstract

Cyclones are devices used in various industries to remove particulate matter from gases and liquids. Commonly used in the power generation, cement, and mining industries, cyclones improve the efficiency and longevity of equipment by removing dust and other small particles that can cause [...] Read more.

Cyclones are devices used in various industries to remove particulate matter from gases and liquids. Commonly used in the power generation, cement, and mining industries, cyclones improve the efficiency and longevity of equipment by removing dust and other small particles that can cause wear and damage. Among centrifugal separation, reverse-flow cyclones are primarily used for particle separation, which can reach heights of several meters on an industrial scale and therefore, are difficult to access for maintenance. A uniflow centrifugal segregation system avoids these drawbacks of reverse-flow cyclones since their accessibility is good and their height usually does not exceed their diameter. The efficiency is a critical aspect of separating systems. This study systematically examines the collection efficiency for particles ranging from 1

μ m

to 29

μ m

in diameter based on varying vane angles of the swirl inducer at flow rates ranging from 130

L

s^{- 1}

to 236

L

s^{- 1}

. Full article

(This article belongs to the Collection Feature Paper Collection in Section 'Purification Technology')

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16 pages, 3030 KiB

Open AccessArticle

Phytochemistry and Biological Activities of Essential Oils from Satureja calamintha Nepeta

by Rajae El Brahimi, Azeddin El Barnossi, Abdelfattah El Moussaoui, Mohamed Chebaibi, Rabie Kachkoul, Asmae Baghouz, Hiba-Allah Nafidi, Ahmad Mohammad Salamatullah, Mohammed Bourhia and Amina Bari

Separations 2023, 10(6), 344; https://doi.org/10.3390/separations10060344 - 5 Jun 2023

Cited by 8 | Viewed by 1716

Abstract

Satureja calamintha nepeta (S. calamintha) has a history of successful use in the treatment of bacterial and fungal diseases. The present study was designed to investigate the chemical composition and antioxidant and antimicrobial activities of essential oils extracted from wild S. [...] Read more.

Satureja calamintha nepeta (S. calamintha) has a history of successful use in the treatment of bacterial and fungal diseases. The present study was designed to investigate the chemical composition and antioxidant and antimicrobial activities of essential oils extracted from wild S. calamintha (EOSS) and domesticated S. calamintha (EOSD) for comparison purposes. Hydrodistillation was used to extract the essential oils (EOs), while GC/MS was used for chemical analysis. Antioxidant activity was studied using DPPH and FRAP assays. Antifungal activity was performed against Candida albicans, Aspergillus niger, Aspergillus flavus, and Fusarium oxysporum), while antibacterial activity was tested against clinically resistant bacteria, namely Staphylococcus aureus, Escherichia coli, Bacillus subtilis, and Proteus mirabilis. By using ab=n in silico approach, the antioxidant and antimicrobial activities of the main compounds of EOSS and EOSD were also investigated. The yields obtained of EOSS and EOSD were 2.80% and 1.95%, respectively, with a dominance of eucalyptol, pulegone and rotundifolone. Concerning the antioxidant power, the IC50 values recorded by the use of the DPPH assay were in the range of 23.03 ± 4.30 and 24.09 ± 4.38 μg/mL for EOSS and EOSD, respectively, while by using the FRAP assay, the EC₅₀ values were in the range of 55.38 ± 2.16 and 60.72 ± 7.71 μg/mL for EOSS and EOSD, respectively. Importantly, both essential oils of EOSS and EOSD exhibited good antibacterial activity against all studied bacteria; notably, the inhibition zone ranged from 14 ± 0.00 to 48.67 ± 1.15 mm and the MICs ranged from 0.37 ± 0.00 to 5.96 ± 0.00 µg/mL. Similarly, the studied EOs showed important antifungal activities compared to all the studied fungi, wherein the inhibition percentage ranged from 47.33 ± 1.15 to 89.18 ± 0.75%, while the MICs ranged from 0.18 ± 0.00 to 2.98 ± 0.00 µg/mL. The molecular docking results showed that piperitenone and pulegone strongly inhibited human acetylcholinesterase, whereas (+)-Isomenthone and piperitenone strongly inhibited S. aureus nucleoside diphosphate kinase, and E. coli beta-ketoacyl-[acyl carrier protein] synthase, respectively. The outcome of this article suggests that EOs of S. calamintha can be developed as alternative agents to manage drug-resistant phenomena and free radical issues. Full article

(This article belongs to the Special Issue Essential Oils: Extraction, Chemical Composition, and Biological Activity)

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16 pages, 2377 KiB

Open AccessArticle

Development and Validation of UPLC–MS/MS Method for Quantitative Analysis of 5-Fluorouracil in Aqueous Humor of Rabbits

by Mohd Abul Kalam, Sulaiman S. Alhudaithi, Adel Ali Alhowyan, Muzaffar Iqbal, Mohammad Raish, Abdullah K. Alshememry, Musaed Alkholief, Aliyah A. Almomen and Aws Alshamsan

Separations 2023, 10(6), 343; https://doi.org/10.3390/separations10060343 - 2 Jun 2023

Viewed by 1770

Abstract

5-Fluorouracil (5-FU) is now used in eye drops for the management of conjunctival malignant melanoma, intraepithelial neoplasia, and corneal and conjunctival squamous cell carcinoma. The previously used methods for 5-FU quantification in AqH were time-consuming and less sensitive. Herein, a highly perceptive bioanalytical [...] Read more.

5-Fluorouracil (5-FU) is now used in eye drops for the management of conjunctival malignant melanoma, intraepithelial neoplasia, and corneal and conjunctival squamous cell carcinoma. The previously used methods for 5-FU quantification in AqH were time-consuming and less sensitive. Herein, a highly perceptive bioanalytical UPLC–MS/MS method was developed for the quantitative determination of 5-FU in the aqueous humor (AqH) of rabbits using allopurinol as the internal standard (IS). The 5-FU and IS were well separated in an Acquity™ HILIC column. Acetonitrile and 10 mM of ammonium acetate at 95:5 (v/v) were isocratically pumped at a 0.3 mL/min flow rate with a total runtime of 2.5 min. AqH samples were processed with a liquid–liquid extraction method in ethyl acetate. The 5-FU and IS were identified in the negative mode with electrospray ionization. The parent to daughter ion transitions for the 5-FU and IS occurred at m/z 128.92→41.68 and 134.80→64.10, respectively, as quantified using the multiple reaction monitoring mode. The developed method was validated with the ICH-Harmonized Guideline for Bioanalytical Method Validation, and the parameters were within acceptable limits. The calibration curve was linear at the 10.5–2000 ng/mL concentration range, with a correlation coefficient (R²) of 0.9946, and the lower limit of detection was 3.55 ng/mL. The developed and validated method was rapid, sensitive, accurate and robustly able to quantify 5-FU in rabbit AqH. The method was effectively applied to establish the ocular pharmacokinetics of 5-FU following the topical instillation of 5-FU-containing preparations in rabbits. Full article

(This article belongs to the Special Issue Application of Chromatography in Pharmaceutical and Biomedical Analysis)

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15 pages, 3289 KiB

Open AccessArticle

Experimental Design Approach for Development of HPLC Method for Simultaneous Analysis of Triamcinolone, Nystatin, and Gramicidin in Industrial Wastewater

by Loubna Elsharkawy, Maha A. Hegazy, Ahmed E. Elgendy and Rasha M. Ahmed

Separations 2023, 10(6), 342; https://doi.org/10.3390/separations10060342 - 1 Jun 2023

Cited by 1 | Viewed by 2295

Abstract

This study used an experimental design approach to optimize an HPLC method for the simultaneous determination of three pharmaceutical residues (triamcinolone, nystatin, and gramicidin) in industrial wastewater samples. The goal of using an experimental design approach was to maximize the method performance through [...] Read more.

This study used an experimental design approach to optimize an HPLC method for the simultaneous determination of three pharmaceutical residues (triamcinolone, nystatin, and gramicidin) in industrial wastewater samples. The goal of using an experimental design approach was to maximize the method performance through separation enhancement and shortening the time of analysis and/or minimizing the environmental effects through the reduction in wastes and sample treatment. To achieve this goal, two steps were performed: a full factorial screening design for the three chromatographic variables, and optimization design using central composite design to select the optimum conditions that accomplished the highest resolution between adjacent peaks within a minimum run time of less than 5 min. The optimal chromatographic conditions derived from Minitab software using the desirability function were applied. Separation was carried out on a Zorbax C18 column (250 mm × 4.6, 5 μm) with gradient elution of a mobile phase composed of methanol and 0.25 M potassium dihydrogen phosphate buffer (pH 3.6) at different UV detections. For the validation of the developed HPLC method, ICH guidelines were followed, and the obtained results were found to be in compliance with the acceptance criteria. Linearity was over the concentration range of 1.00–25.00 μg/mL for triamcinilone and nystatin and 10.00–50.00 µg/mL for gramicidin. The proposed method was successfully applied to quantify the three studied pharmaceutical compounds in rinsing wastewater samples. Full article

(This article belongs to the Special Issue Sensitivity Enhancement Approaches to the Separation Techniques for Pharmaceutical Analysis and Therapeutic Drug Monitoring)

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15 pages, 4708 KiB

Open AccessArticle

Extractive Distillation Approach to the Separation of Styrene from Pyrolysis Gasoline Feedstock Coupled with Deep Desulfurization

by Guanchu Guo, Chuanlei Liu, Yuxiang Chen, Qiyue Zhao, Weikang Gao, Hao Wang, Fengjing Yang, Benxian Shen, Di Wu and Hui Sun

Separations 2023, 10(6), 341; https://doi.org/10.3390/separations10060341 - 1 Jun 2023

Cited by 1 | Viewed by 2472

Abstract

The separation of mixtures with close boiling points is a critical task in the petrochemical industry, and one such mixture that requires separation is o-xylene/styrene. The STED process is used to separate o-xylene/styrene, which contains a certain amount of organic sulfur in the [...] Read more.

The separation of mixtures with close boiling points is a critical task in the petrochemical industry, and one such mixture that requires separation is o-xylene/styrene. The STED process is used to separate o-xylene/styrene, which contains a certain amount of organic sulfur in the product due to the limitations of the process. In this study, the process underwent enhancements to attain the effective separation of styrene and accomplish deep desulfurization. A mixture of sulfolane (SUL) and N-methylpyrrolidone (NMP) was selected as the extraction solvent after calculating the UNIFAC group contributions. An orthogonal experiment was conducted to investigate the effects of the solvent/oil ratio, reflux ratio, water addition rate, and solvent ratio on the product. The correspondence between each factor and the indexes examined was determined, enabling the optimization and prediction of the styrene product quality. The final optimized conditions for the extractive distillation column are as follows: solvent/oil ratio of 7, reflux ratio of 4.5, water addition rate of 6000 kg/h, and a solvent ratio of 9:1. Under optimal conditions, the purity of the product was observed to be greater than that of the original process and the sulfur content of the product can be reduced to lower than 10 ppm at the cost of an increase of 12.31% in energy consumption. Full article

(This article belongs to the Section Analysis of Energies)

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15 pages, 3492 KiB

Open AccessArticle

Identification and Assessment of Therapeutic Phytoconstituents of Catharanthus roseus through GC-MS Analysis

by Jyoti Rani, Manish Kapoor, Sanju Bala Dhull, Gulden Goksen and Slaven Jurić

Separations 2023, 10(6), 340; https://doi.org/10.3390/separations10060340 - 1 Jun 2023

Cited by 5 | Viewed by 3466

Abstract

The leaves of Catharanthus roseus (L.) G. Don contain a large number of diverse secondary metabolites, making them comparably complex. The Catharanthus genus has received increased interest from scientists in recent years due to its extensive applications in several domains, including the pharmaceutical [...] Read more.

The leaves of Catharanthus roseus (L.) G. Don contain a large number of diverse secondary metabolites, making them comparably complex. The Catharanthus genus has received increased interest from scientists in recent years due to its extensive applications in several domains, including the pharmaceutical sector, where precise characterization of its characteristics is required. An effective inquiry technique is needed for chemo-profiling to identify the metabolites in plant samples. The main goal of this research is to provide supplementary data on the chemical composition of the leaves of twenty-five different accessions of C. roseus through the application of gas chromatography-mass spectrometry (GC-MS). The study’s findings reveal the existence of a vast number of phytochemicals, allowing for a comparison of the different accessions. Furthermore, a meticulous statistical analysis of this data using principal components analysis (PCA) and a heatmap, and hierarchical cluster analysis (HCA) may aid in providing more relevant information on C. roseus leaves for possible investigation of their metabolites in further scientific studies. Full article

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11 pages, 2584 KiB

Open AccessArticle

Application of ZnO/WO₃ Composite Nanofiber Photocatalysts in Textile Wastewater Treatment

by Yongxin Xu, Hui Yan and Tiwei Chen

Separations 2023, 10(6), 339; https://doi.org/10.3390/separations10060339 - 31 May 2023

Cited by 4 | Viewed by 1587

Abstract

Semiconductor photocatalysis technology is an environmentally friendly and efficient emerging technology. This method can use sunlight as a driving force to quickly decompose organic pollutants in water bodies. Zinc oxide (ZnO) and tungsten oxide (WO₃) photocatalysts can absorb sunlight and participate [...] Read more.

Semiconductor photocatalysis technology is an environmentally friendly and efficient emerging technology. This method can use sunlight as a driving force to quickly decompose organic pollutants in water bodies. Zinc oxide (ZnO) and tungsten oxide (WO₃) photocatalysts can absorb sunlight and participate in photocatalytic degradation reactions due to their relatively narrow band gap. Highly photosensitive WO₃ nanofibers and ZnO/WO₃ composite nanofibers were fabricated via the electrospinning method. When 100 mg/L of rhodamine B (Rh B) solution was used as the degradation substrate, the degradation efficiencies of WO₃ and ZnO/WO₃ for Rh B dye were 70% and 90%, respectively, after a photocatalytic reaction of 120 min. The surface morphology, crystal structure, and optical properties of ZnO/WO₃ composite nanofibers and WO₃ nanofibers were characterized by SEM, XRD, XPS, and UV-vis absorption spectra, and the experimental results were analyzed and explained using different mechanisms. The results show that ZnO/WO₃ composite nanofibers have better UV-visible light absorption performance, and the sample has a higher UV-visible light utilization rate. This was mainly due to the fact that a P-N heterojunction was formed in the semiconductor composite, and the electron–hole pair could realize rapid separation under the drive of a built-in electric field force, which promoted the migration of carrier. Therefore, the photocatalytic activity of the ZnO/WO₃ catalyst was significantly higher than that of the WO₃ catalyst, which promoted rapid improvement of the photocatalytic degradation efficiency of the Rh B dye. Full article

(This article belongs to the Section Environmental Separations)

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11 pages, 1058 KiB

Open AccessArticle

Identification and Quantification of Polyphenolic Secondary Metabolites in Stem Bark of Ficus religiosa (Moraceae) Using UPLC-HRMS and RP-HPLC-PDA

by Deepak Thakur, Uma Ranjan Lal, Deepak N. Kapoor and Deepak Kumar

Separations 2023, 10(6), 338; https://doi.org/10.3390/separations10060338 - 31 May 2023

Cited by 5 | Viewed by 1963

Abstract

F. religiosa bark has been extensively used in traditional medicinal systems, such as Ayurveda, for its health benefits. The aim of this study was to investigate the secondary metabolites (phenolics and flavonoids) of the hydroalcoholic stem-bark extract from F. religiosa because this plant [...] Read more.

F. religiosa bark has been extensively used in traditional medicinal systems, such as Ayurveda, for its health benefits. The aim of this study was to investigate the secondary metabolites (phenolics and flavonoids) of the hydroalcoholic stem-bark extract from F. religiosa because this plant has been proven to have a beneficial effect on health disorders. Therefore, a pilot study was conducted for the identification and quantification of polyphenolic compounds in F. religiosa bark using sophisticated chromatographical techniques such as UPLC-HRMS and RP-HPLC-PDA. Additionally, total flavonoids, total phenolics and the scavenging profile of the bark were studied using a UV spectrophotometer. A total of 23 compounds identified with UPLC-HRMS were mainly phenolic acids, polyphenolics, and flavonoids (flavanols and proanthocyanidins). Among the identified compounds, gallic acid, catechin, epicatechin, epigallocatechin gallate, and ellagic acid were simultaneously quantified (0.031–0.380%) using RP-HPLC-PDA. Thereafter, the study complied by evaluating the total flavonoids (109.15 ± 1.2 mg RuE/g and 33.78 ± 0.86 mg CaE/g), total phenolics (4.81 ± 1.01 mg GaE/g), and scavenging profiles (IC₅₀ 13.75 ± 0.12 µg/mL) of the F. religiosa bark. This is the first report on the chemical profiling of F. religiosa bark, which is a necessary step to evaluate its nutraceutical properties, paving the way for possible food application. Full article

(This article belongs to the Special Issue Advanced Methods for Separation and Analysis of Natural Products)

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36 pages, 4971 KiB

Open AccessReview

A Comprehensive Review of the Developments in Electrocoagulation for the Removal of Contaminants from Wastewater

by Mohamed Ammar, Ezz Yousef, Muhammed A. Mahmoud, Sherif Ashraf and Jonas Baltrusaitis

Separations 2023, 10(6), 337; https://doi.org/10.3390/separations10060337 - 30 May 2023

Cited by 9 | Viewed by 4926

Abstract

Water organic pollution has become a major issue. A large number of people suffer from the decline in water quality. In addition, polluted water can lead to health problems or excessive deaths. In this regard, an increasingly important method for efficient water treatment [...] Read more.

Water organic pollution has become a major issue. A large number of people suffer from the decline in water quality. In addition, polluted water can lead to health problems or excessive deaths. In this regard, an increasingly important method for efficient water treatment is electrocoagulation (EC), the technology that encompasses a small equipment size combined with a simple operation compared to other water treatment methods. The importance of EC is especially accentuated by the recent decarbonization efforts due to the increasing availability of renewable electricity systems. This review provides an overview of the most recent developments in EC technology as it pertains to wastewater treatment. The EC is preferred for organic wastewater treatment over other traditional treatment methods due to its easy setup and low material costs. Moreover, the EC is very powerful in destabilizing organic impurities by charge neutralization and then coagulating to form flocs. In addition, EC has shown high efficiency not only in removing various organic pollutants but also in emerging persistent contaminants, such as microplastics. For these reasons, the EC mechanisms and related functional modalities are reviewed, as well as extensive details are provided on the diversity of the removed contaminants. Overall, this review provides significant new knowledge of interest for environmental chemical researchers in particular and engineers in general on the details of the EC technology for wastewater treatment and water purification. Full article

(This article belongs to the Special Issue Separation Processes for Effective Removal of Emerging Contaminants from Water and Wastewater)

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11 pages, 3309 KiB

Open AccessArticle

Exploration of Large-Scale Application of Efficient and Clean Utilization of Low-Grade Bauxite

by Yang Chen, Fei Long, Xuejiao Cao, Yibing Li, Weiguang Zhang, Tingan Zhang and Guozhi Lv

Separations 2023, 10(6), 336; https://doi.org/10.3390/separations10060336 - 30 May 2023

Cited by 1 | Viewed by 1740

Abstract

In recent years, the rapid development of the domestic alumina industry has greatly accelerated the consumption of high-alumina–silica-ratio bauxite resources in China. The development of an efficient and clean utilization technology applicable to low-grade bauxite in China is not only a requirement for [...] Read more.

In recent years, the rapid development of the domestic alumina industry has greatly accelerated the consumption of high-alumina–silica-ratio bauxite resources in China. The development of an efficient and clean utilization technology applicable to low-grade bauxite in China is not only a requirement for resource and environmental protection, but also a powerful guarantee to maintain the sustainable development of China’s aluminum industry. Based on this, the authors’ team proposed a new process for the treatment of low-grade bauxite ore via a calcification–carbonization method from the perspective of equilibrium solid-phase reconstruction and achieved the first industrial-scale trial run on the basis of existing laboratory research. The results show that the mass fraction of Na₂O in bauxite residue can be reduced to 0.95% in the treatment of typical diaspore bauxite, the A/S in the bauxite residue can be reduced to 0.85 after two-time carbonization–alumina dissolution, and the actual alumina dissolution rate can reach 81.32%. The relevant results verified the feasibility and advantages of the calcification–carbonization method in industrial production. Full article

(This article belongs to the Special Issue Efficient and Green Recovery of Metal Minerals)

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Separations, Volume 10, Issue 6 (June 2023) – 44 articles

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