Separations

14 pages, 1888 KiB

Open AccessArticle

Investigation of the Distribution and Binding Affinity of Copper to Size-Fractioned Dissolved Organic Matter (DOM) in a Constructed Wetland

by Ming-Yuan Hung, Wei-Hsiang Huang, Liang-Fong Hsu, Chi-Ying Hsieh and Ting-Chien Chen

Separations 2024, 11(6), 191; https://doi.org/10.3390/separations11060191 - 19 Jun 2024

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Abstract

This study investigated the distribution and binding affinity of dissolved copper (Cu) and organic carbon (OC) in size-fractioned dissolved organic matter (DOM) in a constructed wetland (CW). Two sites were studied: one at the inflow (P-1) and one within the wetland (P-2). The [...] Read more.

This study investigated the distribution and binding affinity of dissolved copper (Cu) and organic carbon (OC) in size-fractioned dissolved organic matter (DOM) in a constructed wetland (CW). Two sites were studied: one at the inflow (P-1) and one within the wetland (P-2). The DOMs (<0.45 μm) were separated into six size fractions using a cross-flow ultrafiltration system. In the wetland (P-2), the concentrations of dissolved organic carbon (DOC) increased while the concentrations of Cu decreased. The high molecular weight fraction (1 kDa–0.45 μm, HMW) contained most of the OC mass (57.4–71.2% averages). On the other hand, Cu was almost equally distributed in HMW and low molecular weight fractions (<1 kDa, LMW) with mean HMW percentages of 50.3–51.3%. The mean Cu binding affinity to DOM ratios (CuBA_DOM) was 74.9 ± 24.0 μmol/g-C at site P-1 and 17.3 ± 2.6 μmol/g-C at site P-2. The CuBA_DOM ratios were decreased in wetlands of bulk and size-fractioned DOM (p < 0.001 to p = 0.073). The SUVA₂₅₄ values for bulk DOM solution were 2.54 ± 0.15 and 1.68 ± 0.18 L/mg-C/m, and humidification index (HIX) values were 1.74 ± 0.16 and 2.09 ± 0.19 for sites P-1 and P-2, respectively. Optical indicators suggested that the wetland process decreased aromaticity but increased the humification degree of DOM. Furthermore, the CuBA_DOM ratios positively correlated with SUVA₂₅₄ and HIX within the constructed wetland DOM but not in the influent DOM. Understanding the Cu distribution and binding affinity to size-fractioned DOM makes it possible to develop strategies to mitigate the potential effects of copper pollution in wetlands. Full article

(This article belongs to the Section Environmental Separations)

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17 pages, 1733 KiB

Open AccessArticle

Application of Portable Near-Infrared Instrument for Analysis of Spirulina platensis Aqueous Extracts

by Blaženko Marjanović, Tea Sokač Cvetnić, Davor Valinger, Maja Benković, Tamara Jurina, Jasenka Gajdoš Kljusurić and Ana Jurinjak Tušek

Separations 2024, 11(6), 190; https://doi.org/10.3390/separations11060190 - 18 Jun 2024

Cited by 1 | Viewed by 769

Abstract

Spirulina platensis microalga has become recognized as a promising source of highly nutritious food components to feed the growing global population. Because of its high protein content, abundance of essential amino acids, and excellent digestion, it is employed in human nutrition and there [...] Read more.

Spirulina platensis microalga has become recognized as a promising source of highly nutritious food components to feed the growing global population. Because of its high protein content, abundance of essential amino acids, and excellent digestion, it is employed in human nutrition and there is growing interest in analyzing bioactive compound present in Spirulina platensis microalga. In this work, a portable near-infrared (NIR) spectrometer was used for the monitoring of physicochemical properties (extraction yield (EY), total polyphenols concentration (TPC), total proteins concentration (TP), antioxidant activity measured by (i) the DPPH method (DPPH) and (ii) FRAP method (FRAP)) of Spirulina platensis aqueous extracts. The ultrasound-assisted aqueous extraction (ultrasonic bath with an ultrasound frequency of 35 kHz) of bioactive molecules from Spirulina platensis was performed throughout 30 independent experiments. NIR spectra were recorded in the wavelength range of 900–1700 nm. Raw NIR spectra were subjected to the physicochemical properties applying Principal Component Analysis (PCA), partial least square (PLS), and artificial neural network (ANN) modeling. Results show that ANN models developed for the prediction of TPC and DPPH can be utilized for extraction process control (RER > 10), while the other three models can be employed for screening (RER > 4). Generally, the obtained results indicate significant potential for using portable NIR spectroscopy for the analysis of Spirulina platensis aqueous extracts. Full article

(This article belongs to the Special Issue Analysis, Isolation and Biological Activities of Polyphenols from Terrestrial and Marine Sources)

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20 pages, 5831 KiB

Open AccessArticle

Enhanced Antioxidant Extraction from Lonicerae japonicae Flos Based on a Novel Optimization Strategy with Tailored Deep Eutectic Solvents

by Wen-Wen Deng, Bo Sun, Han Yang, Xiao-Jie Hou, Yong-Jian Zhang, Tian-Xiang Gan, Xin-Yi Cheng, Ao Yuan, Xiao-Yang Dong, Cong-Yu Zhou, Ying Deng, Ya-Qian Xiao, Reza Ghiladi, Hui Li and Jun Wang

Separations 2024, 11(6), 189; https://doi.org/10.3390/separations11060189 - 17 Jun 2024

Viewed by 847

Abstract

Lonicerae japonicae Flos (LJF) is a natural plant containing abundant antioxidant ingredients. In order to extract more antioxidants from LJF, in this study, a novel strategy was proposed for optimizing the extraction factor level by response surface methodology with a tailored deep eutectic [...] Read more.

Lonicerae japonicae Flos (LJF) is a natural plant containing abundant antioxidant ingredients. In order to extract more antioxidants from LJF, in this study, a novel strategy was proposed for optimizing the extraction factor level by response surface methodology with a tailored deep eutectic solvent (DES) as the extraction solvent and antioxidant ability as the evaluation index. After optimizing the composition of DES and the extraction condition, the extracts obtained by our proposed method yielded better antioxidant ability (229.1–249.1 μmol TE/g DW) and higher antioxidant contents (34.2–36.5 mg GAE/g DW for total phenolics and 119.6–123.0 mg RE/g DW for total flavonoids) from LJF in 5 min without organic solvent consumption that were significantly superior to the Chinese Pharmacopoeia extraction method. The K-T solvation parameter and a scanning electron microscope were adopted to explore the extraction mechanism, and the results showed that the polarity and damage effect on plant cells of DES were crucial for the extraction of antioxidants. In addition, after combining the HPLC fingerprint and partial least squares model, chlorogenic acid, rutin, and 3,5-O-Dicaffeoylquinic acid were screened as the antioxidant Q-markers of LJF. This work demonstrates that an optimization strategy based on antioxidant ability and tailored DES has the potential to extract more antioxidants from natural plants. Full article

(This article belongs to the Special Issue Extraction and Analysis of Chemical Compositions of Natural Products and Plants)

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16 pages, 804 KiB

Open AccessEditor’s ChoiceArticle

Simultaneous Determination of Multiresidues of Pesticides and Veterinary Drugs in Agricultural Soil Using QuEChERS and UHPLC–MS/MS

by Michele C. Vicari, Janice F. Facco, Sandra C. Peixoto, Gabriel S. de Carvalho, Luana Floriano, Osmar D. Prestes, Martha B. Adaime and Renato Zanella

Separations 2024, 11(6), 188; https://doi.org/10.3390/separations11060188 - 14 Jun 2024

Cited by 1 | Viewed by 1012

Abstract

Soil is one of the main destinations for pesticides and veterinary drugs used in agriculture and animal production. The negative consequences of the accumulation of these compounds in the environment make it important to monitor these compounds in the soil. In this study, [...] Read more.

Soil is one of the main destinations for pesticides and veterinary drugs used in agriculture and animal production. The negative consequences of the accumulation of these compounds in the environment make it important to monitor these compounds in the soil. In this study, we compared different extraction procedures using solvent shaking, ultrasound, or QuEChERS, and their combinations, for the simultaneous determination of 75 pesticide and seven veterinary drug residues in agricultural soil by ultra-high performance liquid chromatography coupled to serial mass spectrometry (UHPLC–MS/MS). The method using QuEChERS combined with shaking showed the best results for soil using the addition of water, followed by extraction with acetonitrile acidified with acetic acid and shaking in a shaker. For partitioning, anhydrous magnesium sulfate and anhydrous sodium acetate were used. The extract was centrifuged, filtered, and diluted (1:4, v/v) in water for determination by UHPLC–MS/MS. Method validation showed adequate accuracy and precision results, with recoveries between 70 and 120% and RSD ≤ 20% for the vast majority of the compounds evaluated at the spike levels of 10, 25, 50, and 100 μg kg⁻¹. The method limits of detection (LOD) and quantification (LOQ) ranged from 3.0 to 7.5 μg kg⁻¹ and from 10 to 25 μg kg⁻¹, respectively. The method was applied to different agricultural soil samples and proved to be efficient for routine analysis. Full article

(This article belongs to the Collection Feature Paper Collection in Section 'Environmental Separations')

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11 pages, 4012 KiB

Open AccessArticle

The Important Role of Denitrifying Exoelectrogens in Single-Chamber Microbial Fuel Cells after Nitrate Exposure

by Xiaojun Jin, Wenyi Wang, Zhuo Yan and Dake Xu

Separations 2024, 11(6), 187; https://doi.org/10.3390/separations11060187 - 14 Jun 2024

Viewed by 814

Abstract

Wastewater treatment using microbial fuel cells (MFCs) is a potentially useful technology due to its low cost, environmental friendliness, and low sludge production. In this study, a single-chambered air cathode MFC (SCMFC) was developed and investigated regarding its performance and microbial community evolution [...] Read more.

Wastewater treatment using microbial fuel cells (MFCs) is a potentially useful technology due to its low cost, environmental friendliness, and low sludge production. In this study, a single-chambered air cathode MFC (SCMFC) was developed and investigated regarding its performance and microbial community evolution following nitrate exposure. During long-term operation, diverse denitrifiers accumulated on the electrodes to form a denitrifying MFC (DNMFC) with stable activity for nitrate reduction. The DNMFC presented considerably higher electroactivity, stability, and denitrification rates than the SCMFC. Though energy recovery decreased in the DNMFC by partial organics utilized for heterotrophic denitrification, the electron transfer efficiency increased. Geobacter as the absolutely dominant genus in the SCMFC anode was eliminated and replaced by Azonexus and Pseudomonas in the DNMFC. Furthermore, the biomass of Pseudomonas (151.0 ng/μL) in the DNMFC cathode was five-fold higher than that in the SCMFC, although the bacterial community compositions were quite similar. The DNMFC with highly abundant Pseudomonas exhibited much better performance in terms of electrochemical activity and nitrate removal. The evolution process of functional bacteria from the SCMFC to the DNMFC comprehensively reveals the significant role of denitrifying electroactive bacteria in a bioelectrochemical system for nitrogen-containing wastewater treatment. Full article

(This article belongs to the Special Issue Bioelectrochemical Treatment and Purification of Wastewater)

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21 pages, 4459 KiB

Open AccessReview

Green Technology for Fungal Protein Extraction—A Review

by Tanvir Ahmed, Md Suzauddula, Khadiza Akter, Monir Hossen and Md Nazmul Islam

Separations 2024, 11(6), 186; https://doi.org/10.3390/separations11060186 - 13 Jun 2024

Cited by 1 | Viewed by 2960

Abstract

Fungal proteins are highlighted for their nutritional value and bioactive properties, making them a significant alternative to traditional protein sources. This review evaluates various green extraction technologies, including enzymatic-, ultrasound-, higher-pressure homogenization-, microwave-assisted, pulsed electric fields-, and supercritical fluid-assisted extraction, focusing on their [...] Read more.

Fungal proteins are highlighted for their nutritional value and bioactive properties, making them a significant alternative to traditional protein sources. This review evaluates various green extraction technologies, including enzymatic-, ultrasound-, higher-pressure homogenization-, microwave-assisted, pulsed electric fields-, and supercritical fluid-assisted extraction, focusing on their effectiveness in disrupting fungal cell walls and preserving protein integrity. The findings indicate that these technologies could have the potential to improve protein yield and quality, addressing the challenges posed by fungal cell walls’ complex and resilient structure. The review also underscores the bioactivities of fungal proteins, including antifungal, antibacterial, antioxidant, and anticancer properties. The conclusion emphasises the need for further optimisation and scaling of these technologies, as well as exploring a wider range of fungal species to fully understand their potential as sustainable protein sources. Future research directions include refining extraction methods, integrating multiple approaches, and utilising novel green solvents to maximise efficiency and yield. Full article

(This article belongs to the Special Issue Advanced Extraction and Microextraction Techniques and Their Applications in Sample Preparation)

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19 pages, 5539 KiB

Open AccessArticle

Aqueous Two-Phase Flotation Combined with Gold Nanoparticle Colorimetry for Determination of Thiocyanate in Raw Milk

by Bin Jiang, Hongshen Yue, Xinhao Fu, Jiaming Wang, Yu Feng, Chunhong Liu and Dongmei Li

Separations 2024, 11(6), 185; https://doi.org/10.3390/separations11060185 - 13 Jun 2024

Cited by 1 | Viewed by 826

Abstract

Thiocyanates are effective in inhibiting the growth of microorganisms in raw milk to extend shelf life, but excessive addition can cause human health problems. Currently, ion chromatography and spectrophotometry are the main methods used in industry to determine SCN, but the pre-treatment process [...] Read more.

Thiocyanates are effective in inhibiting the growth of microorganisms in raw milk to extend shelf life, but excessive addition can cause human health problems. Currently, ion chromatography and spectrophotometry are the main methods used in industry to determine SCN, but the pre-treatment process is cumbersome and time-consuming and has low sensitivity. Aqueous two-phase flotation (ATPF) technology has the advantages of simplicity, rapidity and economy. In this study, an acetonitrile/ammonium sulfate ATPF–gold nanoparticle (AuNP) colorimetric method was developed for the determination of SCN⁻ in raw milk, and ATPF was used to separate and concentrate SCN⁻ in raw milk to improve the detection sensitivity under convenient and economical conditions. The separation conditions were optimized by single-factor experiments and RSM, while the detection conditions, effects of CTAB concentration, pH and reaction time, were investigated. The “aggregation–anti-aggregation” mechanism of the gold-nano colorimetric method for the determination of SCN⁻ was investigated by UV-vis absorption spectroscopy (UV-vis) and transmission electron microscopy (TEM). Under the optimal separation and detection conditions, the SCN⁻ concentration showed a linear relationship with A630/A520 values in the concentration range of 0–2.5 mg/L with R² of 0.9933, limit of detection (LOD) of 0.0919 mg/L, limit of quantitation (LOQ) of 0.306 mg/L, intra-day precision of 5.3% and spiked recoveries of 80.91–101.25%. In addition, the ATPF-AuNP colorimetric method demonstrated high selectivity and stability. Full article

(This article belongs to the Section Analysis of Food and Beverages)

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27 pages, 9407 KiB

Open AccessReview

Paeoniae Radix Alba and Network Pharmacology Approach for Osteoarthritis: A Review

by Bo Wang, Changcai Bai and Yuanyuan Zhang

Separations 2024, 11(6), 184; https://doi.org/10.3390/separations11060184 - 12 Jun 2024

Viewed by 757

Abstract

Osteoarthritis (OA) is the most common type of arthritis and affects more than 240 million people worldwide; the most frequently affected areas are the hips, knees, feet, and hands. OA pathophysiology is multifactorial, involving genetic, developmental, metabolic, traumatic, and inflammation factors. Therefore, treatments [...] Read more.

Osteoarthritis (OA) is the most common type of arthritis and affects more than 240 million people worldwide; the most frequently affected areas are the hips, knees, feet, and hands. OA pathophysiology is multifactorial, involving genetic, developmental, metabolic, traumatic, and inflammation factors. Therefore, treatments able to address several path mechanisms can help control OA. Network pharmacology is developing as a next-generation research strategy to shift the paradigm of drug discovery from “one drug, one target” to “multi-component, multi-target”. In this paper, network pharmacology is employed to investigate the potential role of Paeoniae Radix Alba (PRA) in the treatment of OA. PRA is a natural product known for its protective effects against OA, which has recently drawn attention because of its ability to provide physiological benefits with fewer toxic effects. This review highlights the anti-inflammatory properties of PRA in treating OA. PRA can be used alone or in combination with conventional therapies to enhance their effectiveness and reduce side effects. The study also demonstrates the use of network pharmacology as a cost-effective and time-saving method for predicting therapeutic targets of PRA in OA treatment. Full article

(This article belongs to the Special Issue Extraction and Analysis of Chemical Compositions of Natural Products and Plants)

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16 pages, 1183 KiB

Open AccessArticle

Simultaneous Determination of Multi-Class Mushroom Toxins in Mushroom and Biological Liquid Samples Using LC-MS/MS

by Junjia Lu, Jing Zhang, Haijiao Li and Chengye Sun

Separations 2024, 11(6), 183; https://doi.org/10.3390/separations11060183 - 12 Jun 2024

Viewed by 1002

Abstract

A comprehensive analytical method based on liquid chromatography–tandem mass spectrometry (LC-MS/MS) was developed for the simultaneous detection of 12 mushroom toxins (ibotenic acid, muscimol, muscarine, β-amanitin, α-amanitin, desoxoviroidin, γ-amanitin, phallisacin, illudin S, phallacidin, phalloidin and illudin M) in mushrooms, serum, urine and simulated [...] Read more.

A comprehensive analytical method based on liquid chromatography–tandem mass spectrometry (LC-MS/MS) was developed for the simultaneous detection of 12 mushroom toxins (ibotenic acid, muscimol, muscarine, β-amanitin, α-amanitin, desoxoviroidin, γ-amanitin, phallisacin, illudin S, phallacidin, phalloidin and illudin M) in mushrooms, serum, urine and simulated gastric fluid. The samples were extracted with water or acetonitrile solution, and the serum sample was further purified with PSA sorbent. Chromatographic separation was performed on an ACQUITY UPLC HSS T3 column with gradient elution using methanol and water containing 1 mM ammonia fluoride as a mobile phase. Mass spectrometric acquisition was performed in electrospray positive ionization mode. Good linearities (R² > 0.994) were obtained for 12 toxins over the range of 0.05~200 µg/L. Matrix-matched calibration curves were used for quantification. The method limits of quantification were 0.01~0.2 mg/kg for mushrooms and 0.15~2.0 µg/L for three biological liquid samples. The mean recoveries of 12 target toxins (spiked at three concentration levels) ranged from 73.0% to 110.3%, with relative standard deviations not exceeding 19.4%, which meets the requirements for the determination of trace compounds in a biological matrix. This method was applied to the analysis of mushroom samples from Yunnan Province. As a result, 11 toxins, not including illudin M, were detected with a concentration range of 0.61~2143 mg/kg. Full article

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14 pages, 4099 KiB

Open AccessArticle

Isotherm, Kinetics, and Adsorption Mechanism Studies of Coal Gasification Coarse Slag as Highly Efficient Phosphate Adsorbents

by Xuzhi Shi, Baoguo Yang, Dayi Qian, Dong Cui, Hongbin Li, Chao Wang, Yuhao Zhu and Tao Yu

Separations 2024, 11(6), 182; https://doi.org/10.3390/separations11060182 - 11 Jun 2024

Viewed by 1059

Abstract

This study investigates the efficacy of a novel low-cost phosphate adsorbent, denoted as SH-CGCS, derived from coal gasification coarse slag (CGCS) via an alkali activation method. SH-CGCS is a mesoporous material with a specific surface area (64 m²/g) approximately six times [...] Read more.

This study investigates the efficacy of a novel low-cost phosphate adsorbent, denoted as SH-CGCS, derived from coal gasification coarse slag (CGCS) via an alkali activation method. SH-CGCS is a mesoporous material with a specific surface area (64 m²/g) approximately six times larger than CGCS (11 m²/g), which enhances its adsorption capacity compared with CGCS. Furthermore, SH-CGCS achieves a phosphate adsorption capacity of 38.5 mg/g in strongly acidic water (pH 3) and demonstrates robust acid resistance, which makes it particularly effective for phosphate removal from acidic wastewater. Results from coexisting anion experiments affirm the good adsorption selectivity of SH-CGCS for phosphate. Moreover, SH-CGCS exhibits proficiency in treating water containing low phosphate concentrations under flowing conditions. The maximum phosphate adsorption capacity of SH-CGCS calculated using the Langmuir model is 23.92 mg/g, surpassing that of other reported adsorbents. Importantly, saturated SH-CGCS can be regenerated and reused, which contributes to its practical applicability. The adsorption mechanisms of SH-CGCS for phosphate involve ligand exchange, inner-sphere complexation, surface precipitation, and electrostatic adsorption. Thus, this study not only enhances the overall utility of CGCS but also presents a simple and efficient method for removing phosphate. Our findings indicate that SH-CGCS holds considerable potential as a phosphate adsorbent, offering a promising solution for wastewater treatment. Full article

(This article belongs to the Section Environmental Separations)

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13 pages, 4810 KiB

Open AccessArticle

Characterization of the Volatilomic Fingerprint of Culinary Aromatic Herbs: A Comparative Study Based on Chemometric Analysis

by Sergio Izcara, Rosa Perestrelo, Sonia Morante-Zarcero, Isabel Sierra and José Sousa Câmara

Separations 2024, 11(6), 181; https://doi.org/10.3390/separations11060181 - 10 Jun 2024

Viewed by 1016

Abstract

Culinary aromatic herbs (CAHs), used worldwide for culinary and industrial purposes, are recognized for their wide range of beneficial health effects including antimicrobial, antioxidant, anti-hyperlipidemic, anti-inflammatory, anti-type 2 diabetes mellitus, antitumorigenic and anticarcinogenic, and anti-hypertensive properties, in addition to glucose- and cholesterol-lowering activities [...] Read more.

Culinary aromatic herbs (CAHs), used worldwide for culinary and industrial purposes, are recognized for their wide range of beneficial health effects including antimicrobial, antioxidant, anti-hyperlipidemic, anti-inflammatory, anti-type 2 diabetes mellitus, antitumorigenic and anticarcinogenic, and anti-hypertensive properties, in addition to glucose- and cholesterol-lowering activities as well as properties that affect mental health and cognition via their phytochemical constituents, such as polyphenols (flavonoids and non-flavonoids), sulfur- and nitrogen-containing compounds, alkaloids, minerals, and vitamins. Moreover, the volatile organic metabolites (VOMs) found in CAHs offer unique analytical biosignatures linked to their sensory qualities and organoleptic characteristics. This study aimed to establish the volatilomic pattern of CAHs commonly used in Europe and in the Mediterranean region, oregano (Origanum vulgare L.) and two savory species: savory (Satureja hortensis L.) and lemon savory (Satureja montana L. var. citriodora). The volatilomic pattern of CAHs was established using headspace solid-phase microextraction (HS-SPME) followed by gas chromatography–mass spectrometry (GC-MS) determination. This is a powerful strategy to unravel the potential health benefits related to the most important VOMs identified in each aromatic herb. This comprehensive understanding will aid in establishing the authenticity of these herbs, while also safeguarding against possible fraudulent activities and adulterations. A total of 112 VOMs from different chemical families were identified. Terpenoids amounted to the major chemical family in the investigated aromatic herbs accounting for 96.0, 95.1, and 79.7% of the total volatile composition for savory, lemon savory, and oregano, respectively. Apart from contributing to flavor profiles, certain identified VOMs also possess bioactive properties, opening interesting avenues for potential application in the food, pharmaceutical, and cosmetic sectors. The volatilomic pattern combined with unsupervised principal component analysis facilitated the differentiation of the aromatic herbs under investigation, revealing the most related VOMs in each sample, which can be used as markers for the authentication of these valuable aromatic herbs, such as caryophyllene oxide (103), camphene (6), p-cymene (23), and borneol (74), among others. In addition, some VOMs have a high influence on the aromatic herb’s bioactive potential, helping to prevent certain diseases including cancer, inflammatory-related diseases, diabetes, and cardiovascular diseases. Full article

(This article belongs to the Special Issue Design and Development of Sample Preparation Procedures for the Determination of Volatile Organic Compounds)

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16 pages, 2514 KiB

Open AccessArticle

Influence of Drying and Storage Conditions on the Volatile Organic Compounds Profile of Spirulina Platensis

by Alberto Ughetti, Veronica D’Eusanio, Lorenzo Strani, Andrea Luca Russo and Fabrizio Roncaglia

Separations 2024, 11(6), 180; https://doi.org/10.3390/separations11060180 - 10 Jun 2024

Viewed by 1077

Abstract

Spirulina platensis (SP) has gained popularity over the last few years, owing to its remarkable nutritional properties and high potential across various industrial sectors. In this study, we analyzed the volatile profile of eight SP samples from the same strain subjected to different [...] Read more.

Spirulina platensis (SP) has gained popularity over the last few years, owing to its remarkable nutritional properties and high potential across various industrial sectors. In this study, we analyzed the volatile profile of eight SP samples from the same strain subjected to different drying (oven-drying, air-drying, and spray-drying) and storing conditions (“freshly prepared” and after 12 months of storage) using HS-SPME-GC-MS. Principal component analysis (PCA) was used as a multivariate technique to discern similarities and differences among the samples. The main aim was to assess the impact of the drying technique on the aroma profile and storage life of SP samples. Air-drying leads to the less pronounced formation of by-products related to heat treatment, such as Maillard and Strecker degradation compounds, but promotes oxidative and fermentative phenomena, with the formation of organic acids and esters, especially during storage. Thermal treatment, essential for limiting degradation and fermentation during storage and extending shelf life, alters the aroma profile through the formation of volatile compounds, such as Strecker aldehydes and linear aldehydes, from amino acid and lipid degradation. High temperatures in spray-drying favor the formation of pyrazines. The findings underscore the trade-offs inherent in choosing an appropriate drying method, thereby informing decision-making processes in industrial settings aimed at optimizing both product quality and efficiency. Full article

(This article belongs to the Special Issue Advanced Research on Extraction and Analysis of Plant Extracts)

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16 pages, 6344 KiB

Open AccessArticle

One-Step Chromatographic Approach for Purifying Peptides and Proteins from Venoms

by Yasmine Boughanmi, Soioulata Aboudou, Kayané Boyadjian, Acil Charouandi, Sarra Bouzid, Thelma Barnetche, Pascal Mansuelle, Régine Lebrun, Didier Gigmes, Harold de Pomyers and Kamel Mabrouk

Separations 2024, 11(6), 179; https://doi.org/10.3390/separations11060179 - 6 Jun 2024

Cited by 1 | Viewed by 1014

Abstract

Animal venoms are intricate and teem with potential for groundbreaking medical advancements. Although traditional methods for purifying venom proteins are effective, they usually require complicated, multi-step processes that lead to lower yields. Our study introduces an efficient, one-step technique for extracting venom-derived proteins [...] Read more.

Animal venoms are intricate and teem with potential for groundbreaking medical advancements. Although traditional methods for purifying venom proteins are effective, they usually require complicated, multi-step processes that lead to lower yields. Our study introduces an efficient, one-step technique for extracting venom-derived proteins through reverse-phase high-performance liquid chromatography (RP-HPLC). We carefully optimized the RP-HPLC process, focusing on the gradient elution conditions and the strategic use of our columns’ stationary phase characteristics, to enhance the effectiveness of our separations. This enabled us to efficiently isolate six venom proteins: melittin (2.846 kDa) from Apis mellifera with a yield of 4.5% and homogeneity of 99%; α-cobratoxin (7.821 kDa) from Naja kaouthia with a yield of 15% and homogeneity of 99%; α-bungarotoxin (7.983 kDa) from Bungarus multicinctus with a yield of 7% and purity of 99%; calciseptine (7.035 kDa) from Dendroaspis polylepis with a yield of 6% and homogeneity of 95%; notexin (13.593 kDa) from Notechis scutatus with a yield of 10% and homogeneity of 95%; and CVFm (150 kDa) from Naja melanoleuca with a yield of 0.8% and homogeneity of 94%. These were all accomplished in one step. This breakthrough simplifies the purification of venom peptides and proteins, making the process more feasible and economical. It paves the way for developing new drugs and promising treatments that are both more effective and precisely targeted. Full article

(This article belongs to the Section Chromatographic Separations)

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10 pages, 2033 KiB

Open AccessBrief Report

Computerized Olfactronic Identification of Persons Using Comprehensive Two-Dimensional Gas Chromatography with Mass Spectrometry

by Luděk Bouška, Petra Pojmanová, Ulrika Malá and Štěpán Urban

Separations 2024, 11(6), 178; https://doi.org/10.3390/separations11060178 - 6 Jun 2024

Viewed by 679

Abstract

This paper demonstrates the possibilities of the computer identification of individuals based on their digitized scent signatures using comprehensive two-dimensional gas chromatography with mass spectrometry. This identification is performed by comparing an unknown digital scent sample with digital scent signatures in a database. [...] Read more.

This paper demonstrates the possibilities of the computer identification of individuals based on their digitized scent signatures using comprehensive two-dimensional gas chromatography with mass spectrometry. This identification is performed by comparing an unknown digital scent sample with digital scent signatures in a database. The olfactronic identification of persons performed by computers follows the olfactoric identification currently performed by trained dogs. Olfactoric identification is considered a subjective method, and therefore it needs to be supported by an objective olfactronic method. The results obtained in this study demonstrate the advantages of olfactronic identification. In addition, the olfactronic identification method makes it possible to compare and store in the database hundreds or even thousands of digital scent signatures based on chemical compounds from samples. A higher recognition percentage of identification is achieved when applying two differently constructed signatures. This article shows that with this approach, the comparison algorithm can reach up to 95-percent correct identification for unknown samples. This is quite a novel point and the rationale of this work. In this study, 400 scent samples from 40 volunteers (20 women and 20 men) were analyzed, where ten scent samples were taken from each person. Full article

(This article belongs to the Section Chromatographic Separations)

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15 pages, 7166 KiB

Open AccessEditor’s ChoiceArticle

The Pollution Characteristics and Fate of Microplastics in Typical Wastewater Treatment Systems in Northern China

by Yi Ma, Zhenkang Bao, Shangying Cai, Qiong Wang, Beibei Dou, Xiangyu Niu, Qingzhen Meng, Penghao Li and Xiaoying Guo

Separations 2024, 11(6), 177; https://doi.org/10.3390/separations11060177 - 6 Jun 2024

Cited by 1 | Viewed by 1024

Abstract

This study focuses on the occurrence status and removal efficiency of microplastics in wastewater treatment plant processes. Analysis of effluent and sludge samples from the Wulongkou and Shuangqiao wastewater treatment plants in Zhengzhou revealed an overall microplastic removal efficiency of 95.64% and 92.53%, [...] Read more.

This study focuses on the occurrence status and removal efficiency of microplastics in wastewater treatment plant processes. Analysis of effluent and sludge samples from the Wulongkou and Shuangqiao wastewater treatment plants in Zhengzhou revealed an overall microplastic removal efficiency of 95.64% and 92.53%, respectively, indicating the effectiveness of wastewater treatment plants in reducing microplastic emissions. Microplastics primarily exist in forms such as fiber, fragment, floc, film, and grain. Fibers are predominant in the effluent of the Wulongkou plant, while fibers and films predominate in the effluent of the Shuangqiao plant. Moreover, microplastics are predominantly sized below 500 μm, with larger microplastics (2–5 mm) exhibiting higher removal efficiencies after secondary treatment. Analysis of microplastic types revealed that PE is the most common type in the effluent of the Wulongkou plant, while the Shuangqiao plant predominantly contains PE and PA66. The abundance of microplastics in sludge samples was found to be 6.4 ± 0.8 items/g and 11.3 ± 2.3 items/g, highlighting sludge as an important sink for microplastics. Surface analysis of microplastics revealed characteristics such as wrinkles and cracks, with energy-dispersive spectroscopy indicating significant adsorption of heavy metal elements such as Zn, Hg, and Pb onto microplastic surfaces in sludge. These findings underscore the importance of microplastic removal in wastewater treatment processes and provide scientific evidence for the control and management of microplastic pollution in the future. Full article

(This article belongs to the Special Issue Adsorption and Remediation of Emerging Pollutants from Water and Soil)

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18 pages, 22284 KiB

Open AccessArticle

Purifying High-Purity Copper via Semi-Continuous Directional Solidification: Insights from Numerical Simulations

by Yao Wu, Yunhu Zhang, Long Zeng and Hongxing Zheng

Separations 2024, 11(6), 176; https://doi.org/10.3390/separations11060176 - 5 Jun 2024

Viewed by 1123

Abstract

High-purity copper is essential for fabricating advanced microelectronic devices, particularly integrated circuit interconnects. As the industry increasingly emphasizes scalable and efficient purification methods, this study investigates the multi-physics interactions during the semi-continuous directional solidification process, utilizing a Cu-1 wt.%Ag model alloy. Coupled simulation [...] Read more.

High-purity copper is essential for fabricating advanced microelectronic devices, particularly integrated circuit interconnects. As the industry increasingly emphasizes scalable and efficient purification methods, this study investigates the multi-physics interactions during the semi-continuous directional solidification process, utilizing a Cu-1 wt.%Ag model alloy. Coupled simulation calculations examine the spatial distribution patterns of the impurity element silver (Ag) within semi-continuously solidified ingots under varying pulling rates and melt temperatures. The objective is to provide technical insights into the utilization of the semi-continuous directional solidification method for high-purity copper purification. The findings reveal that increasing the pulling rate and melt temperature leads to a downward shift in the solid–liquid interface relative to the mold top during processing. Alongside the primary clockwise vortex flow, a secondary weak vortex emerges near the solid–liquid interface, facilitating the migration of the impurity element Ag toward the central axis and amplifying radial impurity fluctuations. Furthermore, diverse pulling rates and melt temperature conditions unveil a consistent trend along the ingot’s height, which is characterized by an initial increase in average Ag content, followed by stabilization and then a rapid ascent during the late stage of solidification, with higher pulling rates and melt temperatures expediting this rapid ascent. Leveraging these insights, a validation experiment using 4N-grade recycled copper in a small-scale setup demonstrates the effectiveness of the semi-continuous directional solidification process for high-purity copper production, with copper samples extracted at 1/4 and 3/4 ingot heights achieving a 5N purity level of 99.9994 wt.% and 99.9993 wt.%, respectively. Full article

(This article belongs to the Special Issue Novel Applications of Separation Technology)

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22 pages, 7092 KiB

Open AccessArticle

Phytochemical Identification and Anti-Oxidative Stress Effects Study of Cimicifugae Rhizoma Extract and Its Major Component Isoferulic Acid

by Jing Liu, Aqian Chang, Hulinyue Peng, Xingbin Yin, Xiaoxv Dong, Changhai Qu and Jian Ni

Separations 2024, 11(6), 175; https://doi.org/10.3390/separations11060175 - 3 Jun 2024

Viewed by 1023

Abstract

Background and Objectives: Cimicifugae Rhizoma, also known as ‘Sheng ma’ in Madeiran, is a widely used Chinese herbal medicine that has several pharmacological qualities, one of which is its antioxidant activity. Isoferulic acid, a prominent phenolic compound found in Cimicifugae Rhizoma, [...] Read more.

Background and Objectives: Cimicifugae Rhizoma, also known as ‘Sheng ma’ in Madeiran, is a widely used Chinese herbal medicine that has several pharmacological qualities, one of which is its antioxidant activity. Isoferulic acid, a prominent phenolic compound found in Cimicifugae Rhizoma, has potent antioxidant properties. This study was aimed to comprehensively analyze the components in Cimicifugae Rhizoma and rat plasma to evaluate the in vitro antioxidant and anti-inflammatory properties of Cimicifugae Rhizoma extract and Isoferulic acid as potential candidates for developing herbal formulations targeting podocyte injury in diabetic nephropathy for further clinical utilization. Materials and Methods: UPLC/Q-TOF-MS and HPLC were utilized as analytical tools to identify components of Cimicifugae Rhizoma extract or rat plasma after administrating it. MPC5 cells were cultured with H₂O₂ and high glucose and subjected to oxidative stress injury. The CXCL12/CXCR4 system plays a crucial role at certain stages of multiple kidney diseases’ injury. Apoptosis-related and target CXCL12/CXCR4/mTOR/Caspase-3 and Cask protein levels were assessed, and the levels of inflammatory-related factors, motility, morphology, ROS level, and apoptosis in podocytes were tested. Results: A total of 82 and 39 components were identified in the Cimicifugae Rhizoma extract and plasma, and Isoferulic acid content was determined as 6.52 mg/g in the Cimicifugae Rhizoma extract. The Cimicifugae Rhizoma extract (1 μg/mL) and Isoferulic acid (10, 25, 50 μM) considerably decreased high glucose and oxidative-stress-mediated toxicity, impaired mobility and adhesion and apoptotic changes in MPC5 cells, and reversed inflammation response. Moreover, the Cimicifugae Rhizoma extract and Isoferulic acid down-regulated Cask, mTOR, and Caspase-3, while significantly blocking the overactivation of CXCL12/CXCR4 in podocytes stimulated by oxidative stress and high glucose. Conclusions: These results indicate that the renal protective mechanism of the Cimicifugae Rhizoma extract and Isoferulic acid on simulating H₂O₂-induced podocyte injury involves mainly the of CXCL12/CXCR4 pathways and the inactivation of oxidative-stress-mediated apoptotic pathways after comprehensive qualitative and quantitative research by UPLC/Q-TOF-MS and HPLC. These findings provide an important efficacy and ingredient basis for further study on the clinical utilities of Cimicifugae Rhizoma and Isoferulic acid on podocyte and kidney impairment. Full article

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

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36 pages, 1446 KiB

Open AccessReview

Urolithins and Their Precursors Ellagic Acid and Ellagitannins: Natural Sources, Extraction and Methods for Their Determination

by Christiana Mantzourani, Eleni Kakouri, Konstantinos Palikaras, Petros A. Tarantilis and Maroula G. Kokotou

Separations 2024, 11(6), 174; https://doi.org/10.3390/separations11060174 - 2 Jun 2024

Cited by 1 | Viewed by 2448

Abstract

In the present review, we discuss the occurrence of ellagitannins (ETs) and ellagic acid (EA) and methods for their isolation from plant materials. We summarize analytical methods, including high-performance liquid chromatography–ultraviolet (HPLC–UV) and liquid chromatography–mass spectrometry (LC–MS), for the determination of ETs, EA [...] Read more.

In the present review, we discuss the occurrence of ellagitannins (ETs) and ellagic acid (EA) and methods for their isolation from plant materials. We summarize analytical methods, including high-performance liquid chromatography–ultraviolet (HPLC–UV) and liquid chromatography–mass spectrometry (LC–MS), for the determination of ETs, EA and their bioactive metabolites urolithins (Uros) in samples of plant and food origin, as well as in biological samples, such as plasma, urine and feces. In addition, the current interest in the bioactivities of Uros is discussed in brief. Full article

(This article belongs to the Special Issue Applications of Separation and Purification Techniques for Natural Products Derived from Plants Source)

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19 pages, 6198 KiB

Open AccessArticle

In Situ Formed Organic Ion-Associate Liquid-Phase Microextraction without Centrifugation from Aqueous Solutions Using Thymol Blue and Estrogens

by Sachiko Osada, Seira Takahashi, Kazuto Sazawa, Hideki Kuramitz, Nozomi Kohama, Takuya Okazaki, Shigeru Taguchi and Noriko Hata

Separations 2024, 11(6), 173; https://doi.org/10.3390/separations11060173 - 2 Jun 2024

Viewed by 591

Abstract

In this study, we present a method for ion-associated liquid phase (IALP) separation and concentration of analytes from an aqueous matrix into an IALP formed in situ by the charge neutralization reaction of organic cations and anions, without centrifugation. The effects of various [...] Read more.

In this study, we present a method for ion-associated liquid phase (IALP) separation and concentration of analytes from an aqueous matrix into an IALP formed in situ by the charge neutralization reaction of organic cations and anions, without centrifugation. The effects of various factors on the extraction efficiency and other parameters are investigated, whereas no instrumental stirring, such as vortexing or ultrasonics, is required because the solvent (IALP) is formed in situ. The organic cation and anion used are ethylhexyloxypropylammonium and dodecyl sulfate, respectively. The developed in situ IALP microextraction method for phase separation without centrifugation is tested using the thymol blue dye and several endocrine disruptors. The tested endocrine disruptors (bisphenol A, 17β-estradiol, 17α-ethinylestradiol, and estrone) are analyzed via high-performance liquid chromatography/fluorescence detection, with respective detection limits of 0.02, 0.02, 0.02, and 0.4 μg L⁻¹, and the corresponding enrichment factor ranging from 47 to 71. This IALP microextraction method can be used to separate and concentrate environmental water samples of different matrices. The employed IALP is fast and easy to use, enables an approximately 100-fold analyte concentration, and has a high affinity for estrogens, thus holding promise for the separation, concentration, and quantitation of diverse trace analytes. Full article

(This article belongs to the Section Purification Technology)

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15 pages, 810 KiB

Open AccessArticle

The Essential Oil Composition of Eryngium galioides Lam.—An Endemic Species of the Iberian Peninsula

by Jesús Palá-Paúl, Rubén Abad-Calderón, María José Pérez-Alonso, Joseph J. Brophy and Ana C. Soria

Separations 2024, 11(6), 172; https://doi.org/10.3390/separations11060172 - 1 Jun 2024

Viewed by 951

Abstract

The Eryngium L. genus belongs to the Apiaceae family and, with about 250 species, has a cosmopolitan distribution. Only fourteen of the twenty-six species described in Flora Europaea grow in the Iberian Peninsula. One of these is Eryngium galioides Lam., a small annual [...] Read more.

The Eryngium L. genus belongs to the Apiaceae family and, with about 250 species, has a cosmopolitan distribution. Only fourteen of the twenty-six species described in Flora Europaea grow in the Iberian Peninsula. One of these is Eryngium galioides Lam., a small annual plant (2–30 cm) that grows in open dry places in the mid-west of the Iberian Peninsula. For this study, the whole plant (aerial parts and roots) of this species was gathered in Guadalajara (Spain). The essential oil of this population was extracted by hydro-distillation and analyzed by gas chromatography (GC) and gas chromatography coupled to mass spectrometry (GC-MS). It is worth noting that this species gave rise to a relatively high essential oil yield (0.48%) in comparison with other species of this genus. E. galioides oil consisted of a complex mixture of more than 70 compounds. The main constituents of this oil were identified as valencene (49.7%) and a phyllocladene isomer (23.7%), both representing more than the 70% of the total oil. Other representative compounds of this oil were found to be β-chamigrene (6.0%), γ-muurolene (3.4%), (E)-caryophyllene (3.0%) and β-elemene (1.6%). As far as we know, this is the first report about the chemical composition of E. galioides essential oils. With this work, we contribute to the knowledge of this genus and provide a chemical and botanical basis to promote the in vitro cultivation of E. galioides as a source of essential oils rich in bio-actives for application in different fields. Full article

(This article belongs to the Special Issue Analysis, Isolation and Biological Activities of Polyphenols from Terrestrial and Marine Sources)

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23 pages, 2206 KiB

Open AccessReview

Extraction and Purification of Catechins from Tea Leaves: An Overview of Methods, Advantages, and Disadvantages

by Oana Cioanca, Ionut-Iulian Lungu, Ioana Mita-Baciu, Silvia Robu, Ana Flavia Burlec, Monica Hancianu and Florina Crivoi

Separations 2024, 11(6), 171; https://doi.org/10.3390/separations11060171 - 1 Jun 2024

Cited by 1 | Viewed by 3523

Abstract

This review study explores the complex methods involved in the extraction and purification of polyphenols, specifically catechins, prominent compounds that are bioactive and found in plant-based extracts and foods like tea. This study also addresses the challenges that may arise from the complex [...] Read more.

This review study explores the complex methods involved in the extraction and purification of polyphenols, specifically catechins, prominent compounds that are bioactive and found in plant-based extracts and foods like tea. This study also addresses the challenges that may arise from the complex chemical structure of catechins and their inherent variability across botanical sources. Despite these shortcomings and obstacles, catechins and catechin derivatives present significant potential, particularly in healthcare but also in the food industry. Their enhanced antioxidant properties have been exhaustively investigated and associated with countless health benefits, making them promising agents with numerous applications, most notably in healthcare against chronic diseases. Furthermore, catechins have numerous applications across various industries, including food and beverage, cosmetics, agriculture, and materials science. This review is a compilation of the most notable and recent research found in the literature and emphasizes the importance of continued research and innovation in catechin separation, extraction, and utilization, which hold promise for advancing human health and technological progress across multiple domains. Full article

(This article belongs to the Special Issue Advanced Research on Extraction and Analysis of Plant Extracts)

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22 pages, 3840 KiB

Open AccessArticle

Remediation of Methyl Orange Dye in Aqueous Solutions by Green Microalgae (Bracteacoccus sp.): Optimization, Isotherm, Kinetic, and Thermodynamic Studies

by Ahmad Al Shra’ah, Abdullah T. Al-Fawwaz, Mohammed M. Ibrahim and Eid Alsbou

Separations 2024, 11(6), 170; https://doi.org/10.3390/separations11060170 - 30 May 2024

Viewed by 1084

Abstract

This study aims to assess the ability of old, immobilized fresh, and free fresh green microalgae (a Bracteacoccus sp.) to remove methyl orange (MO) dye from aqueous solutions. The effects of four factors, including initial MO concentration (5–25 mg L⁻¹), adsorbent [...] Read more.

This study aims to assess the ability of old, immobilized fresh, and free fresh green microalgae (a Bracteacoccus sp.) to remove methyl orange (MO) dye from aqueous solutions. The effects of four factors, including initial MO concentration (5–25 mg L⁻¹), adsorbent dose (0.02–0.10 g mL⁻¹), temperature (4–36 °C), and contact time (5–95 min), were examined. The Box–Behnken design (BBD) was used to determine the number of required experiments and the optimal conditions expected to provide the highest removal percentage of MO dye from aqueous solutions. The experimental data were applied to four isotherm models (Langmuir, Freundlich, Dubinin–Radushkevich (D–R), and Temkin isotherm models) and three kinetic models (pseudo–first–order, pseudo–second–order, and Elovich kinetic models). The results indicate that the highest removal of MO (97%) could be obtained in optimal conditions consisting of an initial MO concentration of 10.0 mg L⁻¹, an adsorbent dose of 0.10 g mL⁻¹, a temperature of 20 °C, and a contact time of 75 min. Moreover, the experimental data were best fitted by the Langmuir and Temkin isotherm models and followed a pseudo-second-order kinetic model. The interaction between MO and the Bracteacoccus sp. was confirmed by UV and ESI/MS analyses, indicating that MO removal occurred via both sorption and degradation processes. Full article

(This article belongs to the Special Issue Adsorption and Remediation of Emerging Pollutants from Water and Soil)

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14 pages, 2068 KiB

Open AccessArticle

The Prevalence of Benzodiazepine Use among Italian Drivers in 15,988 Cases of Driving License Regranting from 2015 to 2023: Risks and Implications for Driving Fitness

by Lucrezia Stefani, Federico Mineo, Leonardo Romani, Francesca Vernich, Carmelo Russo, Luigi Tonino Marsella and Roberta Tittarelli

Separations 2024, 11(6), 169; https://doi.org/10.3390/separations11060169 - 29 May 2024

Viewed by 1104

Abstract

The use of benzodiazepines is strongly associated with an increased risk of traffic accidents due to their side effects of sedation and drowsiness, which can significantly impair driving performance. The main aim of our study was to investigate the trend of benzodiazepine use [...] Read more.

The use of benzodiazepines is strongly associated with an increased risk of traffic accidents due to their side effects of sedation and drowsiness, which can significantly impair driving performance. The main aim of our study was to investigate the trend of benzodiazepine use over nine years (2015–2023) in a population of 15,988 subjects who had their license suspended for driving under the influence (DUI) of alcohol or drugs. Among the 15,988 users accessed to our laboratory, 924 tested positive for at least one benzodiazepine. An increase in the number of positive-testing users was observed in the period 2015–2018, followed by a slight decrease in 2019. Overall, the trend of benzodiazepine use was stable over the next four years (2020–2023), with the highest incidence in 2022. The most common benzodiazepines, and/or metabolites, found in urine samples were α-OH-alprazolam (28.66%; n = 366) and oxazepam (27.25%; n = 348). Several cases of mixed positivity were observed in the study population. The main substances taken with benzodiazepines were cocaine and Δ9-tetrahydrocannabinol. Our findings suggest that people taking benzodiazepines should be monitored, as these have a relevant impact on driving ability in addition to significant interindividual differences in the behavioral effects of benzodiazepines on driving performance. Full article

(This article belongs to the Special Issue Forensic Toxicology: Biological Sampling and Development of Analytical Techniques)

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11 pages, 1080 KiB

Open AccessArticle

Simultaneous Quantification of Twelve Compounds from Bamboo/Wood Vinegar by Gas Chromatography-Mass Spectrometry

by Jianjun Wang, Bao Zhang, Hang Xun, Xi Yao and Feng Tang

Separations 2024, 11(6), 168; https://doi.org/10.3390/separations11060168 - 28 May 2024

Cited by 1 | Viewed by 903

Abstract

Bamboo vinegar is a liquid biomass with a huge yield and complex chemical composition. At present, the relative quantification of bamboo vinegar has been investigated in most studies. To analyze twelve compounds from bamboo vinegar simultaneously, gas chromatography-mass spectrometry and an external standard [...] Read more.

Bamboo vinegar is a liquid biomass with a huge yield and complex chemical composition. At present, the relative quantification of bamboo vinegar has been investigated in most studies. To analyze twelve compounds from bamboo vinegar simultaneously, gas chromatography-mass spectrometry and an external standard method were used to develop an analytical method. In this method, chromatographic separations of all compounds were above 1.5. The linear range was between 0.100 and 10.000 mg/L, and the coefficient of determination (R²) was between 0.9981 and 0.9997, indicating a good linear relationship. The limit of detection (LOD) was between 0.004 and 0.780 mg/L; the limit of quantitation (LOQ) was between 0.016 and 3.120 mg/L; the relative standard deviations (RSDs) of instrument precision and method stability were less than 8%; the recovery rate was between 89.25% and 113.77%, and its RSD was between 0.44% and 5.70%. Using this method, fourteen bamboo vinegars and six wood vinegars were analyzed, and it was found that the content of propionic acid, phenol, and 2-methoxyphenol was higher in most samples. In addition, the differences in physicochemical properties between distilled bamboo vinegar and its original solution after atmospheric distillation were investigated. Full article

(This article belongs to the Special Issue Comprehensive Separations of Complex Mixtures by Gas Chromatography/Mass Spectrometry (Volume II))

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19 pages, 4562 KiB

Open AccessArticle

Early Identification of Olive Oil Defects throughout Shelf Life

by Flávia Freitas, Maria João Cabrita and Marco Gomes da Silva

Separations 2024, 11(6), 167; https://doi.org/10.3390/separations11060167 - 27 May 2024

Viewed by 947

Abstract

The unique aroma and flavor of extra virgin olive oil (EVOO) are generally associated with its volatile composition, which includes a variety of components responsible for positive attributes as well as sensory defects which result from chemical oxidation processes and the action of [...] Read more.

The unique aroma and flavor of extra virgin olive oil (EVOO) are generally associated with its volatile composition, which includes a variety of components responsible for positive attributes as well as sensory defects which result from chemical oxidation processes and the action of exogenous enzymes. In this study, a robust analytical method, headspace solid-phase microextraction combined with gas chromatography–mass spectrometry (HS-SPME-GC/MS), was developed to tentatively identify volatile organic compounds (VOCs) as markers of positive and negative attributes, correlating them with relative percentages to estimate the risk of disqualification during the shelf life of EVOO. Significant differences (p < 0.05) were identified in the levels of VOCs over time, mainly those derived from the lipoxygenase (LOX) pathway. Principal component analysis (PCA) was applied to process the experimental data. The ratio of E-2-hexenal to acetic acid allowed for the prediction of the disqualification of monovarietal EVOO by the sensory panel. Full article

(This article belongs to the Section Analysis of Food and Beverages)

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30 pages, 3729 KiB

Open AccessReview

Current Trends and Technological Advancements in the Study of Honey Bee-Derived Peptides with an Emphasis on State-of-the-Art Approaches: A Review

by Wissam K. Al-Rubaie, Dhia F. Al-Fekaiki, Alaa Kareem Niamah, Deepak Kumar Verma, Smita Singh and Ami R. Patel

Separations 2024, 11(6), 166; https://doi.org/10.3390/separations11060166 - 27 May 2024

Cited by 1 | Viewed by 1826

Abstract

Honey is a natural product that is used by a large number of people because of its distinctive compositional constituents, which have a considerable impact on its market value. The distinctive combination of amino acids and sugars found in honey’s composition, along with [...] Read more.

Honey is a natural product that is used by a large number of people because of its distinctive compositional constituents, which have a considerable impact on its market value. The distinctive combination of amino acids and sugars found in honey’s composition, along with its peptide content, could potentially provide several benefits to human health. During the past few years, cutting-edge techniques have been developed and used for the purpose of investigating, identifying, and characterizing peptides that are produced from honey bees. Therefore, the purpose of this review is to examine current trends and technological advancements in the study of honey bee-derived peptides, focusing on innovative and cutting-edge methods. Furthermore, this review explores various attributes of honey and its components, including the honey bee-derived peptide defensin-1. In addition, this review investigates various methods for separating and purifying peptides, as well as the factors that affect these methods. Additionally, defensin-1, a peptide produced by honey bees, is discussed along with its antioxidant and antimicrobial capabilities. In addition, this review focuses on cutting-edge and innovative omic methods used to study honey bee peptides, as well as the significance of artificial intelligence tools in their investigation. Consequently, the review paper delves into various significant obstacles faced by researchers and scientists studying honey bee peptides, while also offering an extensive range of fascinating opportunities and possibilities for future research for those interested in groundbreaking discoveries in this area. Full article

(This article belongs to the Section Analysis of Food and Beverages)

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22 pages, 13618 KiB

Open AccessArticle

Accessing the Medicinal Potential of Mallotus philippensis: Comprehensive Exploration of Antioxidant and Antibacterial Properties through Phytochemical Analysis and Extraction Techniques

by Ahmad Ali, Hangping Chen, He Xu, Shuo Wang and Shun Yao

Separations 2024, 11(6), 165; https://doi.org/10.3390/separations11060165 - 27 May 2024

Viewed by 1787

Abstract

Plants serve as reservoirs of bioactive compounds endowed by nature, rendering them promising subjects for investigating chemical diversity. Despite their potential, much remains untapped, whether in standardized extracts or isolated pure compounds. This unexplored terrain has paved the way for significant discoveries in [...] Read more.

Plants serve as reservoirs of bioactive compounds endowed by nature, rendering them promising subjects for investigating chemical diversity. Despite their potential, much remains untapped, whether in standardized extracts or isolated pure compounds. This unexplored terrain has paved the way for significant discoveries in pharmaceuticals. Notably, research has delved into the medicinal properties of Mallotus philippensis, a prominent plant in South Asia. Employing meticulous extraction techniques such as maceration, the fruit of this plant underwent initial antimicrobial screening, revealing encouraging results. Subsequent fractionation of the plant’s extracts via liquid–liquid extractions, utilizing dichloromethane and absolute ethanol, facilitated further analysis. Evaluating these fractions for antibacterial activity demonstrated efficacy against various pathogenic microorganisms, particularly Pseudomonas aeruginosa and Escherichia coli, notably by the ethanolic and dichloromethane extracts. Furthermore, a comprehensive phytochemical analysis unveiled the presence of alkaloids, flavonoids, saponins, glycosides, phenols, and tannins. An assessment of the extracts’ antioxidant potential via the 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging assay showcased significant activity, with a radical scavenging rate of 97%. This underscores the significance of utilizing fruit remnants, which are often rich in valuable chemical constituents yet commonly discarded, thereby adding value to both the species and the environment. Further investigation focused on the composition of Mallotus philippensis fruit, encompassing volatile and non-volatile metabolites through HPLC-MS analysis. Additionally, this study introduced the application of ionic liquid-loaded polysulfone microcapsules to enrich target constituents from crude extracts. An exploration of the key separation conditions, results, and recycling performance of these microcapsules provided insights for future research endeavors. Overall, this comprehensive study of Mallotus philippensis fruit extracts establishes a foundation for the ongoing exploration and development of this medicinal plant. Full article

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

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18 pages, 9752 KiB

Open AccessArticle

Carwash Oily Wastewater Separated by Ultrafiltration

by Piotr Woźniak and Marek Gryta

Separations 2024, 11(6), 164; https://doi.org/10.3390/separations11060164 - 25 May 2024

Cited by 1 | Viewed by 723

Abstract

In the present study, oily wastewater generated during car washing was separated using ultrafiltration (UF). Wastewater was collected from the settling tank of two manual car washes. In addition to pollutants removed from cars, such wastewater contains surfactants, the impact of which on [...] Read more.

In the present study, oily wastewater generated during car washing was separated using ultrafiltration (UF). Wastewater was collected from the settling tank of two manual car washes. In addition to pollutants removed from cars, such wastewater contains surfactants, the impact of which on the process of ultrafiltration has been analyzed. For this purpose, the application of commercial UF polyethersulfone (PES) membranes (10 and 100 kDa) and polyvinylidene fluoride (PVDF) tubular membranes (100 kDa) was comprehensively examined. Almost 100% removal of oil contaminants was achieved; however, intensive fouling was noticed. The membrane morphology and deposit composition were studied using a scanning electron microscope coupled with energy dispersion spectrometry. The fouling phenomenon was reduced by washing the membranes with an alkaline cleaning agent (pH = 11.5), which is used in car washes to remove insects. The filtration/membrane washing cycle was repeated many times to achieve stable operation of the membrane modules. The UF process was carried out for 120–140 h, and the separation efficiency was analyzed based on the rejection of dextrans, COD, BOD, total N and P, turbidity, and anionic surfactants. It has been found that cyclic repeated washing did not deteriorate the membrane’s performance, and a permeate with a turbidity of 0.12–0.35 NTU was obtained. Thus, cleaning agents used for washing cars can also be used for membrane cleaning. Full article

(This article belongs to the Special Issue Advanced Oil–Water Separation Technology)

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15 pages, 1857 KiB

Open AccessArticle

Accumulation of Particles in an Annular Centrifugal Contactor Cascade and the Effect upon the Extraction of Nitric Acid

by Alastair Baker, Alex Fells, Natalia Domenech-Garcia, Chris J. Maher and Bruce C. Hanson

Separations 2024, 11(6), 163; https://doi.org/10.3390/separations11060163 - 23 May 2024

Viewed by 1286

Abstract

Centrifugal contactors (CCs) are a technology candidate for the development of advanced reprocessing flowsheets. While they offer many advantages, such as process intensification, there are still uncertainties regarding their industrial deployment. The presence of particles in the process streams in particular may present [...] Read more.

Centrifugal contactors (CCs) are a technology candidate for the development of advanced reprocessing flowsheets. While they offer many advantages, such as process intensification, there are still uncertainties regarding their industrial deployment. The presence of particles in the process streams in particular may present a challenge to both performance and operability. Preliminary studies have been undertaken to evaluate the accumulation of particles in the contactors and the effect upon the extraction behaviour of nitric acid. Aluminium oxide (Al₂O₃) particles were suspended in the aqueous feed solution during the operation of a three-stage, 40 mm diameter CC cascade. The presence of insoluble solid particles in the aqueous feed, up to 7 g/L, were not observed to affect phase separation and entrainment under the experimental conditions investigated. The particles were centrifuged out of solution and accumulated as a thin cake/bed in the rotors of each stage. This work also illustrates that particles do entrain through the cascade. The predominant effect on the rate of accumulation was particle concentration in the aqueous feed solution, and increasing solids loading was observed to have an impact upon the extraction of nitric acid across the cascade. Full article

(This article belongs to the Section Separation Engineering)

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14 pages, 3318 KiB

Open AccessEditor’s ChoiceArticle

Hyphenation of Thermodesorption into GC × GC-TOFMS for Odorous Molecule Detection in Car Materials: Column Sets and Adaptation of Second Column Dimensions to TD Pressure Constraints

by Romain Klein, José Dugay, Jérôme Vial, Didier Thiébaut, Guy Colombet, Donatien Barreteau and Guillaume Gruntz

Separations 2024, 11(6), 162; https://doi.org/10.3390/separations11060162 - 23 May 2024

Viewed by 788

Abstract

Vehicle interior air quality is an issue of growing interest among car manufacturers and customers. GC-MS is the benchmark method for the analysis of indoor air or material emissions. It is suitable for the quantification of target pollutants and the most abundant compounds. [...] Read more.

Vehicle interior air quality is an issue of growing interest among car manufacturers and customers. GC-MS is the benchmark method for the analysis of indoor air or material emissions. It is suitable for the quantification of target pollutants and the most abundant compounds. It fails, however, to uncover the true molecular complexity of these samples. In the present study, we describe the development of a TD-GC × GC-TOFMS method designed to detect polar and potentially odorous molecules in car material emissions. Attention is paid to the hyphenation of the thermodesorber and the gas chromatograph, both at software and hardware levels, and the constraints due to pressure limitations on the thermodesorber (evaluated at 414 kPa/60 psi at the end of the temperature ramp and at 138 kPa/20 psi at rest). A compromise was made for the 2D column length and diameter to balance separation and pressure (50 × 0.18 × 0.18 cm × mm × µm + 60 cm transfer line selected). On various materials, we were able to observe several hundreds of polar molecules, among them were between 75 and 150 odorants per material. This work lays the foundation for the widespread screening of potential odorants in car material emissions. Full article

(This article belongs to the Collection Feature Paper Collection in Section Chromatographic Separations)

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Separations, Volume 11, Issue 6 (June 2024) – 33 articles

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