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A special issue of Molecules (ISSN 1420-3049). This special issue belongs to the section "Analytical Chemistry".

Deadline for manuscript submissions: closed (15 April 2018) | Viewed by 62968

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Dr. Joselito P. Quirino

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Australian Centre of Research on Separation Science, School of Physical Science, University of Tasmania, Hobart, Tasmania, Australia
Interests: capillary electrophoresis; liquid chromatography; mass spectrometry; sample concentration; green sample preparation
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Special Issue Information

Dear Colleagues,

Analytical chemistry is a central science that enables the developments in other chemical, as well as in biological fields. Recently, the principles of green or sustainable chemistry have been actively implemented in analytical chemistry, where the methods developed for various applications are designed such that the use and generation of hazardous substances is reduced or even eliminated. For example, in extraction or separation analytical methods, traditional organic solvents are slowly being replaced by renewable or green solvents. Miniaturisation of analytical systems, such as for extraction, separation, and/or detection, significantly reduce the amounts of volumes of reagents and solvents used. There are also analytical methods based on electrochemistry, chemical sensing, mass spectrometry (MS), and nuclear magnetic resonance (NMR) that eliminate or reduce sample preparation, which typically requires organic solvents. Chemometrics have also been used to aid in the development of green analytical chemistry.

This Special Issue aims to celebrate the advancements in green analytical chemistry, which encompass all measurement techniques for all types of applications that minimise or eliminate the generation of chemical waste. Researchers in microextraction (e.g., solid-phase, dispersive liquid-liquid, supercritical fluid, cloud point, electro-membrane), separations (chromatography and electrophoresis), flow injection analysis, MS, sensors, NMR, miniaturized analytical techniques, and chemometrics are warmly invited to propose state-of-the-art reviews, perspectives, and research papers to be published in this Special Issue of Molecules.

Dr. Joselito P. Quirino
Guest Editor

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Keywords

Green sample pre-treatment and preparation
Supercritical fluid extraction
Solid-phase microextraction
Cloud-point extraction
Dispersive liquid-liquid extraction
Membrane-based extraction
Green chromatography
Micro- and nano-liquid chromatography
Green spectroscopy and spectrometry
Flow injection analysis
Capillary electrophoresis
Electrochemistry
Mass spectrometry
Nuclear magnetic resonance
Miniaturized extraction and separation
Chemical sensing
Miniaturized analysis
Chemometrics

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Published Papers (11 papers)

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Research

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12 pages, 3809 KiB

Open AccessArticle

Non-Destructive and Rapid Variety Discrimination and Visualization of Single Grape Seed Using Near-Infrared Hyperspectral Imaging Technique and Multivariate Analysis

by Yiying Zhao, Chu Zhang, Susu Zhu, Pan Gao, Lei Feng and Yong He

Molecules 2018, 23(6), 1352; https://doi.org/10.3390/molecules23061352 - 4 Jun 2018

Cited by 44 | Viewed by 4500

Abstract

Hyperspectral images in the spectral range of 874–1734 nm were collected for 14,015, 14,300 and 15,042 grape seeds of three varieties, respectively. Pixel-wise spectra were preprocessed by wavelet transform, and then, spectra of each single grape seed were extracted. Principal component analysis (PCA) was conducted on the hyperspectral images. Scores for images of the first six principal components (PCs) were used to qualitatively recognize the patterns among different varieties. Loadings of the first six PCs were used to identify the effective wavelengths (EWs). Support vector machine (SVM) was used to build the discriminant model using the spectra based on the EWs. The results indicated that the variety of each single grape seed was accurately identified with a calibration accuracy of 94.3% and a prediction accuracy of 88.7%. An external validation image of each variety was used to evaluate the proposed model and to form the classification maps where each single grape seed was explicitly identified as belonging to a distinct variety. The overall results indicated that a hyperspectral imaging (HSI) technique combined with multivariate analysis could be used as an effective tool for non-destructive and rapid variety discrimination and visualization of grape seeds. The proposed method showed great potential for developing a multi-spectral imaging system for practical application in the future. Full article

(This article belongs to the Special Issue Green Analytical Chemistry)

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9 pages, 282 KiB

Open AccessArticle

Expectation-Maximization Model for Substitution of Missing Values Characterizing Greenness of Organic Solvents

by Gabriela Łuczyńska, Francisco Pena-Pereira, Marek Tobiszewski and Jacek Namieśnik

Molecules 2018, 23(6), 1292; https://doi.org/10.3390/molecules23061292 - 28 May 2018

Cited by 7 | Viewed by 3329

Abstract

Organic solvents are ubiquitous in chemical laboratories and the Green Chemistry trend forces their detailed assessments in terms of greenness. Unfortunately, some of them are not fully characterized, especially in terms of toxicological endpoints that are time consuming and expensive to be determined. Missing values in the datasets are serious obstacles, as they prevent the full greenness characterization of chemicals. A featured method to deal with this problem is the application of Expectation-Maximization algorithm. In this study, the dataset consists of 155 solvents that are characterized by 13 variables is treated with Expectation-Maximization algorithm to predict missing data for toxicological endpoints, bioavailability, and biodegradability data. The approach may be particularly useful for substitution of missing values of environmental, health, and safety parameters of new solvents. The presented approach has high potential to deal with missing values, while assessing environmental, health, and safety parameters of other chemicals. Full article

(This article belongs to the Special Issue Green Analytical Chemistry)

12 pages, 1700 KiB

Open AccessArticle

Comparison of the Conventional and Electroenhanced Direct-Immersion Solid-Phase Microextraction for Sampling of Nicotine in Biological Fluids of the Human Body

by Sana Abdolhosseini, Ali Reza Ghiasvand and Nahid Heidari

Molecules 2018, 23(5), 1171; https://doi.org/10.3390/molecules23051171 - 14 May 2018

Cited by 7 | Viewed by 3557

Abstract

A stainless steel fiber was made porous and adhesive by platinization and then coated by nanostructured polypyrrole (PPy), using an appropriate electrophoretic deposition (EPD) method. The morphological surface structure and functional groups of the PPy-coated fiber were studied using SEM (Scanning electron microscope) instrument. The prepared fiber was used for comparison of direct immersion (DI) and electroenhanced direct immersion solid-phase microextraction (EE-DI-SPME) of nicotine in human plasma and urine samples followed by gas chromatography flame ionization detector (GC-FID) determination. The effects of the influential experimental parameters on the efficiency of the DI-SPME and EE-DI-SPME methods, including the pH and ionic strength of the sample solution, applied Direct current (DC) voltage, extraction temperature and time and stirring rate, were optimized. Under the optimal conditions, the calibration curves for the DI-SPME-GC-FID and EE-DI-SPME-GC-FID methods were linear over the ranges of 0.1–10.0 μg mL⁻¹ and 0.001–10.0 μg mL⁻¹, respectively. The relative standard deviations (RSDs, n = 6) were found to be 6.1% and 4.6% for the DI and EE strategies, respectively. The LODs (limit of detection) of the DI-SPME-GC-FID and EE-DI-SPME-GC-FID methods were found to be 10 and 0.3 ng mL⁻¹, respectively. The relative recovery values (for the analysis of 1 µg mL⁻¹ nicotine) were found to be 91–110% for EE-DI-SPME and 75–105% for DI-SPME. The enrichment factors for DI-SPME and EE-DI-SPME sampling were obtained as 38,734 and 50,597, respectively. The results indicated that EE-SPME was more efficient for quantitation of nicotine in biological fluids. The developed procedure was successfully carried out for the extraction and measurement of nicotine in real plasma and urine samples. Full article

(This article belongs to the Special Issue Green Analytical Chemistry)

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16 pages, 2441 KiB

Open AccessArticle

Ultrasonically Modified Amended-Cloud Point Extraction for Simultaneous Pre-Concentration of Neonicotinoid Insecticide Residues

by Rawikan Kachangoon, Jitlada Vichapong, Rodjana Burakham, Yanawath Santaladchaiyakit and Supalax Srijaranai

Molecules 2018, 23(5), 1165; https://doi.org/10.3390/molecules23051165 - 12 May 2018

Cited by 17 | Viewed by 3781

Abstract

An effective pre-concentration method, namely amended-cloud point extraction (CPE), has been developed for the extraction and pre-concentration of neonicotinoid insecticide residues. The studied analytes including clothianidin, imidacloprid, acetamiprid, thiamethoxam and thiacloprid were chosen as a model compound. The amended-CPE procedure included two cloud point processes. Triton™ X-114 was used to extract neonicotinoid residues into the surfactant-rich phase and then the analytes were transferred into an alkaline solution with the help of ultrasound energy. The extracts were then analyzed by high-performance liquid chromatography (HPLC) coupled with a monolithic column. Several factors influencing the extraction efficiency were studied such as kind and concentration of surfactant, type and content of salts, kind and concentration of back extraction agent, and incubation temperature and time. Enrichment factors (EFs) were found in the range of 20–333 folds. The limits of detection of the studied neonicotinoids were in the range of 0.0003–0.002 µg mL⁻¹ which are below the maximum residue limits (MRLs) established by the European Union (EU). Good repeatability was obtained with relative standard deviations lower than 1.92% and 4.54% for retention time (t_R) and peak area, respectively. The developed extraction method was successfully applied for the analysis of water samples. No detectable residues of neonicotinoids in the studied samples were found. Full article

(This article belongs to the Special Issue Green Analytical Chemistry)

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9 pages, 1785 KiB

Open AccessArticle

Determination of Biogenic Amines in Seawater Using Capillary Electrophoresis with Capacitively Coupled Contactless Conductivity Detection

by Elbaleeq A. Gubartallah, Ahmad Makahleh, Joselito P. Quirino and Bahruddin Saad

Molecules 2018, 23(5), 1112; https://doi.org/10.3390/molecules23051112 - 8 May 2018

Cited by 24 | Viewed by 4356

Abstract

A rapid and green analytical method based on capillary electrophoresis with capacitively coupled contactless conductivity detection (C⁴D) for the determination of eight environmental pollutants, the biogenic amines (putrescine, cadaverine, spermidine, spermine, tyramine, 2-phenylamine, histamine and tryptamine), is described. The separation was achieved under normal polarity mode at 24 °C and 25 kV with a hydrodynamic injection (50 mbar for 5 s) and using a bare fused-silica capillary (95 cm length × 50 µm i.d.) (detection length of 10.5 cm from the outlet end of the capillary). The optimized background electrolyte consisted of 400 mM malic acid. C⁴D parameters were set at a fixed amplitude (50 V) and frequency (600 kHz). Under the optimum conditions, the method exhibited good linearity over the range of 1.0–100 µg mL⁻¹ (R² ≥ 0.981). The limits of detection based on signal to noise (S/N) ratios of 3 and 10 were ≤0.029 µg mL⁻¹. The method was used for the determination of seawater samples that were spiked with biogenic amines. Good recoveries (77–93%) were found. Full article

(This article belongs to the Special Issue Green Analytical Chemistry)

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11 pages, 2764 KiB

Open AccessArticle

Screening and Identification for Immunological Active Components from Andrographis Herba Using Macrophage Biospecific Extraction Coupled with UPLC/Q-TOF-MS

by Yaqi Wang, Jiaojiao Jiao, Yuanzhen Yang, Ming Yang and Qin Zheng

Molecules 2018, 23(5), 1047; https://doi.org/10.3390/molecules23051047 - 30 Apr 2018

Cited by 17 | Viewed by 4117

Abstract

The method of cell biospecific extraction coupled with UPLC/Q-TOF-MS has been developed as a tool for the screening and identification of potential immunological active components from Andrographis Herba (AH). In our study, a macrophage cell line (RAW264.7) was used to extract cell-combining compounds from the ethanol extract of AH. The cell binding system was then analyzed and identified by UPLC/Q-TOF-MS analysis. Finally, nine compounds, which could combine with macrophages, in an ethanol extract of AH were detected by comparing basic peak intensity (BPI) profiles of macrophages before and after treatment with AH. Then they were identified as Andrographidine E (1), Andrographidine D (2), Neoandrographolide (3), Dehydroandrographolide (4), 5, 7, 2′, 3′-tetramethoxyflavone (5), β-sitosterol (7), 5-hydroxy-7, 2′, 3′-trimethoxyflavone (8) and 5-hydroxy-7, 8, 2′, 3′-tetramethoxyflavone (9), which could classified into five flavonoids, three diterpene lactones, and one sterol. Their structures were recognized by their characteristic fragment ions and fragmentations pattern of diterpene lactones and flavonoids. Additionally, the activity of compounds 3, 4, and 7 was tested in vitro. Results showed that these three compounds could decrease the release of NO (p < 0.01) in macrophages remarkably. Moreover, 3, 4, and 7 showed satisfactory dose-effect relationships and their IC₅₀ values were 9.03, 18.18, and 13.76 μg/mL, respectively. This study is the first reported work on the screening of immunological active components from AH. The potential immunological activity of flavonoids from AH has not been reported previously. Full article

(This article belongs to the Special Issue Green Analytical Chemistry)

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13 pages, 3036 KiB

Open AccessArticle

Rapid Determination of Chlorophyll and Pheophytin in Green Tea Using Fourier Transform Infrared Spectroscopy

by Xiaoli Li, Ruiqing Zhou, Kaiwen Xu, Jie Xu, Juanjuan Jin, Hui Fang and Yong He

Molecules 2018, 23(5), 1010; https://doi.org/10.3390/molecules23051010 - 26 Apr 2018

Cited by 53 | Viewed by 6914

Abstract

The chlorophyll, pheophytin, and their proportions are critical factors to evaluate the sensory quality of green tea. This research aims to establish an effective method to determine the quantification of chlorophyll and pheophytin in green tea, based on Fourier transform infrared (FT–IR) spectroscopy. First, five brands of tea were collected for spectral acquisition, and the chlorophyll and pheophytin were measured using the reference method. Then, a relation between these two pigments and FT–IR spectroscopy were developed based on chemometrics. Additionally, the characteristic IR wavenumbers of these pigments were extracted and proved to be effective for a quantitative determination. Successively, non-linear models were also built based on these characteristic wavenumbers, obtaining coefficients of determination of 0.87, 0.80, 0.85 and 0.89; and relative predictive deviations of 2.77, 2.62, 2.26 and 3.07 for the four pigments, respectively. These results demonstrate the feasibility of FT–IR spectroscopy for the determination of chlorophyll and pheophytin. Full article

(This article belongs to the Special Issue Green Analytical Chemistry)

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9 pages, 996 KiB

Open AccessArticle

Flow Injection Analysis with Direct UV Detection Following Electric Field Driven Membrane Extraction

by Hong Heng See, Nor Akma Mamat and Peter C. Hauser

Molecules 2018, 23(5), 1000; https://doi.org/10.3390/molecules23051000 - 25 Apr 2018

Cited by 5 | Viewed by 4607

Abstract

A method for on-line matrix elimination to enable selective quantification of ultraviolet absorbing analytes by a flow-injection analysis procedure is described. Selectivity is achieved by electric field driven extraction across a polymer inclusion membrane. The method was demonstrated on the example of the determination of naproxen from spiked human urine. Membranes of 10 μm thickness were employed which consisted of 7.5 mg cellulose triacetate as base polymer, 5 mg of o-nitrophenyl octyl ether as plasticizer and 7.5 mg of Aliquat 336 as cationic carrier. Ten μL of sample was introduced into a continuous stream of background solution consisting of 100 µM aqueous NaClO₄ with a flow rate of 2 μL/min while applying a voltage of 150 V to the extraction cell. The target ion was electrokinetically transported across the membrane and enriched in 1.5 μL of a stagnant acceptor solution. This was subsequently pumped past a flow-through UV detector for quantification. The method showed a linear range from 5 to 200 µM with a correlation coefficient of 0.9978 and a reproducibility of typically 7% (n = 8). The detection limit of the method for naproxen was 2 µM. Full article

(This article belongs to the Special Issue Green Analytical Chemistry)

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15 pages, 1098 KiB

Open AccessArticle

Preconcentration of Trace Neonicotinoid Insecticide Residues Using Vortex-Assisted Dispersive Micro Solid-Phase Extraction with Montmorillonite as an Efficient Sorbent

by Khwankaew Moyakao, Yanawath Santaladchaiyakit, Supalax Srijaranai and Jitlada Vichapong

Molecules 2018, 23(4), 883; https://doi.org/10.3390/molecules23040883 - 11 Apr 2018

Cited by 24 | Viewed by 7237

Abstract

In this work, we investigated montmorillonite for adsorption of neonicotinoid insecticides in vortex-assisted dispersive micro-solid phase extraction (VA-d-μ-SPE). High-performance liquid chromatography with photodiode array detection was used for quantification and determination of neonicotinoid insecticide residues, including thiamethoxam, clothianidin, imidacloprid, acetamiprid, and thiacloprid. In this method, the solid sorbent was dispersed into the aqueous sample solution and vortex agitation was performed to accelerate the extraction process. Finally, the solution was filtered from the solid sorbent with a membrane filter. The parameters affecting the extraction efficiency of the proposed method were optimized, such as amount of sorbent, sample volume, salt addition, type and volume of extraction solvent, and vortex time. The adsorbing results show that montmorillonite could be reused at least 4 times and be used as an effective adsorbent for rapid extraction/preconcentration of neonicotinoid insecticide residues. Under optimum conditions, linear dynamic ranges were achieved between 0.5 and 1000 ng mL⁻¹ with a correlation of determination (R²) greater than 0.99. Limit of detection (LOD) ranged from 0.005 to 0.065 ng mL⁻¹, while limit of quantification (LOQ) ranged from 0.008 to 0.263 ng mL⁻¹. The enrichment factor (EF) ranged from 8 to 176-fold. The results demonstrated that the proposed method not only provided a more simple and sensitive method, but also can be used as a powerful alternative method for the simultaneous determination of insecticide residues in natural surface water and fruit juice samples. Full article

(This article belongs to the Special Issue Green Analytical Chemistry)

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9 pages, 430 KiB

Open AccessArticle

Fast and Simple Analytical Method for Direct Determination of Total Chlorine Content in Polyglycerol by ICP-MS

by Agata Jakóbik-Kolon, Andrzej Milewski, Piotr Dydo, Magdalena Witczak and Joanna Bok-Badura

Molecules 2018, 23(2), 487; https://doi.org/10.3390/molecules23020487 - 23 Feb 2018

Cited by 6 | Viewed by 3959

Abstract

The fast and simple method for total chlorine determination in polyglycerols using low resolution inductively coupled plasma mass spectrometry (ICP-MS) without the need for additional equipment and time-consuming sample decomposition was evaluated. Linear calibration curve for ³⁵Cl isotope in the concentration range 20–800 µg/L was observed. Limits of detection and quantification equaled to 15 µg/L and 44 µg/L, respectively. This corresponds to possibility of detection 3 µg/g and determination 9 µg/g of chlorine in polyglycerol using studied conditions (0.5% matrix-polyglycerol samples diluted or dissolved with water to an overall concentration of 0.5%). Matrix effects as well as the effect of chlorine origin have been evaluated. The presence of 0.5% (m/m) of matrix species similar to polyglycerol (polyethylene glycol—PEG) did not influence the chlorine determination for PEGs with average molecular weights (MW) up to 2000 Da. Good precision and accuracy of the chlorine content determination was achieved regardless on its origin (inorganic/organic). High analyte recovery level and low relative standard deviation values were observed for real polyglycerol samples spiked with chloride. Additionally, the Combustion Ion Chromatography System was used as a reference method. The results confirmed high accuracy and precision of the tested method. Full article

(This article belongs to the Special Issue Green Analytical Chemistry)

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Review

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25 pages, 994 KiB

Open AccessReview

Greening Reversed-Phase Liquid Chromatography Methods Using Alternative Solvents for Pharmaceutical Analysis

by Moussa Yabré, Ludivine Ferey, Issa Touridomon Somé and Karen Gaudin

Molecules 2018, 23(5), 1065; https://doi.org/10.3390/molecules23051065 - 2 May 2018

Cited by 150 | Viewed by 15005

Abstract

The greening of analytical methods has gained increasing interest in the field of pharmaceutical analysis to reduce environmental impacts and improve the health safety of analysts. Reversed-phase high-performance liquid chromatography (RP-HPLC) is the most widely used analytical technique involved in pharmaceutical drug development and manufacturing, such as the quality control of bulk drugs and pharmaceutical formulations, as well as the analysis of drugs in biological samples. However, RP-HPLC methods commonly use large amounts of organic solvents and generate high quantities of waste to be disposed, leading to some issues in terms of ecological impact and operator safety. In this context, greening HPLC methods is becoming highly desirable. One strategy to reduce the impact of hazardous solvents is to replace classically used organic solvents (i.e., acetonitrile and methanol) with greener ones. So far, ethanol has been the most often used alternative organic solvent. Others strategies have followed, such as the use of totally aqueous mobile phases, micellar liquid chromatography, and ionic liquids. These approaches have been well developed, as they do not require equipment investments and are rather economical. This review describes and critically discusses the recent advances in greening RP-HPLC methods dedicated to pharmaceutical analysis based on the use of alternative solvents. Full article

(This article belongs to the Special Issue Green Analytical Chemistry)

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