Extraction High-performance Liquid Chromatography Research Articles

Gas Purge–Microsyringe Extraction Coupled with Liquid Chromatography and Fluorescence Detection for the Determination of Aldehydes from Fried Meat

In this study, a green, simple, and sensitive method was developed for the analysis of aliphatic aldehydes from fried meat by using a modified gas purge–microsyringe extraction (GP–MSE) system in combination with high-performance liquid chromatography (HPLC) with fluorescence detection. The modified GP–MSE system possessed two gas channels and showed better recoveries for compounds with diverse density in comparison with one gas channel GP–MSE system. Target compounds in fried meat were effectively extracted without the traditional solvent extraction and lipid removing process, while the HPLC sensitivity of aldehydes was enhanced by introducing 2-(12-benzo[b]acridin-5(12H)-yl)-acetohydrazide (BAAH) with excellent fluorescence property into the molecules. Parameters influencing the extraction efficiency and HPLC sensitivity were optimized. The limits of detection (LODs) ranged from 0.30 to 0.45 μg/kg, and the limits of quantification (LOQs) ranged from 1.0 to 1.5 μg/kg. The recoveries of the target compounds were in the range of 86.9 to 95.6%. The proposed method was successfully applied to the analysis of aldehydes in fried meat samples. Formaldehyde, acetaldehyde, pentanal, hexanal, heptanal, octanal, nonaldehyde, and decanal were all found in fried meat samples with concentrations ranging from 0.05 to 17.8 mg/kg.

Development of a new extraction technique and HPLC method for the analysis of non-psychoactive cannabinoids in fibre-type Cannabis sativa L. (hemp)

The present work was aimed at the development and validation of a new, efficient and reliable technique for the analysis of the main non-psychoactive cannabinoids in fibre-type Cannabis sativa L. (hemp) inflorescences belonging to different varieties. This study was designed to identify samples with a high content of bioactive compounds, with a view to underscoring the importance of quality control in derived products as well. Different extraction methods, including dynamic maceration (DM), ultrasound-assisted extraction (UAE), microwave-assisted extraction (MAE) and supercritical-fluid extraction (SFE) were applied and compared in order to obtain a high yield of the target analytes from hemp. Dynamic maceration for 45min with ethanol (EtOH) at room temperature proved to be the most suitable technique for the extraction of cannabinoids in hemp samples.The analysis of the target analytes in hemp extracts was carried out by developing a new reversed-phase high-performance liquid chromatography (HPLC) method coupled with diode array (UV/DAD) and electrospray ionization-mass spectrometry (ESI–MS) detection, by using an ion trap mass analyser. An Ascentis Express C18 column (150mm×3.0mm I.D., 2.7μm) was selected for the HPLC analysis, with a mobile phase composed of 0.1% formic acid in both water and acetonitrile, under gradient elution. The application of the fused-core technology allowed us to obtain a significant improvement of the HPLC performance compared with that of conventional particulate stationary phases, with a shorter analysis time and a remarkable reduction of solvent usage.The analytical method optimized in this study was fully validated to show compliance with international requirements. Furthermore, it was applied to the characterization of nine hemp samples and six hemp-based pharmaceutical products. As such, it was demonstrated to be a very useful tool for the analysis of cannabinoids in both the plant material and its derivatives for pharmaceutical and nutraceutical applications.

Polydimethylsiloxane/MIL-100(Fe) coated stir bar sorptive extraction-high performance liquid chromatography for the determination of triazines in environmental water samples

Polydimethylsiloxane (PDMS)/MIL-100(Fe) coated stir bar was prepared by sol gel technique, and good preparation reproducibility was achieved with relative standard deviations (RSDs) ranging from 2.6% to 7.5% (n=7) and 3.6% to 10.8% (n=7) for bar-to-bar and batch-to-batch, respectively. Compared with commercial PDMS coated stir bar (Gerstel) and PEG coated stir bar (Gerstel), the prepared PDMS/MIL-100(Fe) stir bar showed better extraction efficiency for target triazines compounds. It also exhibited relatively fast extraction/desorption kinetics and long lifespan. Based on it, a method of PDMS/MIL-100(Fe) coated stir bar sorptive extraction (SBSE)-high performance liquid chromatography-ultraviolet detector (HPLC-UV) was developed for the determination of six triazines (simazine, atrazine, prometon, ametryn, prometryne and prebane) in environmental water samples. Several parameters affecting SBSE of six target triazines including extraction time, stirring rate, sample pH, ionic strength, desorption solvent and desorption time were investigated. Under the optimal experimental conditions, the limits of detection (LODs, S/N=3) were found to be in the range of 0.021–0.079μgL−1. The repeatability RSDs were in the range of 2.3–6.3% (n=7, c=0.5μgL−1) and the enrichment factors (EFs) ranged from 51.1 to 102-fold (theoretical EF was 200-fold). The proposed method was applied to the analysis of target triazines in environmental water samples, with recoveries of 98.0–118% and 94.0–107% for spiked East Lake water and local pond water samples, respectively.

Simultaneous determination of acidic phytohormones in cucumbers and green bean sprouts by ion-pair stir bar sorptive extraction-high performance liquid chromatography

A simple, sensitive and inexpensive method of ion-pair stir bar sorptive extraction (IP-SBSE) combined with high performance liquid chromatography -ultraviolet (HPLC-UV) detection was developed for the simultaneous determination of three acidic phytohormones (salicylic acid (SA), indole-3-acetic acid (IAA), and abscisic acid (ABA)) in vegetables. With the addition of cationic surfactant-cetyltrimethylammonium bromide (CTAB) in sample solutions, ion pair between CTAB and target phytohormones were formed, leading to an improvement of the extraction efficiency for target phytohormones by C18 silica coated SBSE. The factors affecting the extraction efficiency of three target phytohormones by IP-C18 coated SBSE were optimized, and the optimal experimental conditions were established. Under the optimal conditions, the limits of detection for SA, IAA and ABA obtained by IP-C18-SBSE-HPLC-UV were 2.7, 2.1 and 0.3μgL−1, with the relative standard deviations of 6.0%, 5.0% and 8.3%, respectively, and the enrichment factor was 32–49-fold. The developed method was applied to the determination of SA, IAA and ABA in cucumbers and green bean sprouts, and the recoveries of SA, IAA and ABA for the spiked samples were between 72.8% and 109.5%.

Isolation and purification of seven catechin compounds from fresh tea leaves by semi-preparative liquid chromatography

An effective and simple method was established to simultaneously purify seven tea catechins (gallocatechin (GC), epigallocatechin (EGC), catechin (C), epigallocatechin-3-O-gallate (EGCG), epicatechin (EC), epigallocatechin-3-O-(3-O-methyl)-gallate (EGCG3"Me) and epicatechin-3-O-gallate (ECG)) from fresh tea leaves by semi-preparative high performance liquid chromatography (HPLC). Fresh leaves of Tieguanyin tea were successively extracted with methanol and chloroform. Then crude catechins were precipitated from the aqueous fraction of chloroform extraction by adding lead subacetate. Crude catechins were used for the isolation of the seven target catechin compounds by semi-preparative HPLC. Methanol-water and acetonitrile-water were sequentially used as mobile phases. After two rounds of semi-preparative HPLC, all target compounds were achieved with high purities (>90%). The proposed method was tested on two additional tea cultivars and showed similar results. This method demonstrated a simple and efficient strategy based on solvent extraction, ion precipitation and semi-preparative HPLC for the preparation of multiple catechins from tea leaves.

Determination of polycyclic aromatic hydrocarbons in airborne particles by microwave extraction-high performance liquid chromatography

A method by using microwave extraction and high performance liquid chromatography was developed to determine polycyclic aromatic hydrocarbons (PAHs) in airborne particles. The glass/quartz fiber filter, on which particles adsorbed, was extracted with a mixed solvent n-hexane/acetone (1:1, v/v) using microwave, and the subsequent purification of the extract was carried out by a florisil cartridge. The prepared sample was determined by high performance liquid chromatography coupled with photodiode array (PDA) and fluorescence dual-detector. The target compounds showed good linearity between the mass concentration of 20.0 μg/L and 500 μg/L, with the correlation coefficients not less than 0.9960. The spiked recoveries of target compounds in blank filter ranged from 56.3%-101%. The current method has been applied to investigate the distribution of PAHs in airborne particles in Nanjing City.

Validation of a new high-throughput method to determine urinary S-phenylmercapturic acid using low-temperature partitioning extraction and ultra high performance liquid chromatography-mass spectrometry.

A new highly sensitive and environmentally friendly analytical method, using low-temperature partition extraction and ultra-high-performance liquid chromatography with tandem mass spectrometry, without the use of a labeled analyte, was developed and validated to determine and quantify urinary S-phenylmercapturic acid in urine samples. The World Health Organization, in its guidelines for air quality in Europe, recognizes that benzene is carcinogenic to humans and there is no safe level of exposure. Urinary S-phenylmercapturic acid is a sensitive and specific biological marker of exposure to benzene. The new analytical method, extraction, and analysis, were linear in the working range between 0.1 and 200.0μg/L, precise (relative standard deviation lower than 6.0%), accurate (97.0-105.0%), and sensitive. The method's limits of detection and quantification were 0.02 and 0.084μg/L, respectively. The recovery with the low-temperature partition extraction was 96.1%, with relative standard deviation less than 3.8%. The method is simple, accurate, and reproducible, and has been successfully applied in the evaluation of nonoccupational exposure to benzene, by urinary S-phenylmercapturic acid in urine samples.

Development and Application of an Extraction and Quantitative HPLC Method for Sulforaphene in Radish

Sulforaphene, an isothiocyanate generated by the conversion of glucoraphenin in radish (Raphanus sativus L.), plays an important role in plants as a defensive compound and has been shown to have anti-cancer properties. However, a reliable method for the determination of sulforaphene in radish has not yet been established. In the present study, the enzymolysis conditions, extraction solvent and extraction conditions employed to obtain sulforaphene from radish were all optimized using single factor experiments and orthogonal testing. During these trials, sulforaphene was separated and quantified using reverse phase C18 high performance liquid chromatography (HPLC), employing methanol:water (3:7 ν/ν) as the mobile phase at a flow rate of 0.3mL · min−1 together with a detection wavelength of 245nm. Evaluation of this newly established method showed good linearity between the sulforaphene concentration and the characteristic peak area over the range of 5 to 200μg · mL−1 (R2 = 0.9996). This method was thus found to be precise. It was established that sulforaphene was extracted from radish with 95.48% efficiency (RSD = 0.94%) using the optimized conditions. This same technique was successfully applied to the quantification of sulforaphene in the fleshy roots of different radish germplasms as a means of selecting the germplasms with the highest sulforaphene levels.

Transformation of Adsorbed Aflatoxin B1 on Smectite at Elevated Temperatures

AbstractAflatoxins cause liver damage and suppress immunity. Through adsorption, smectites can be used to reduce the bioavailability of aflatoxins. To further reduce the toxicity of aflatoxins and to eliminate the treatments of aflatoxin-loaded smectites, the ability to degrade the aflatoxin adsorbed to non-toxic or less toxic compounds is desirable. The objective of the present study was to investigate the effects of temperature and the exchange cation on the transformation of adsorbed aflatoxin B1 on smectite. An AfB1-Ca-smectite (sm) complex was synthesized. To enhance the Lewis acidity of the complexes, the exchanged calcium in the complex was replaced with Mn and Cu to obtain AfB1-Mn-sm and AfB1-Cu-sm complexes, respectively. The aflatoxin-sm complexes and pure aflatoxin B1 were dried at 60°C in aluminum cups, and heated from 100 to 200°C in 25°C steps. Aflatoxin B1 and its transformation products were extracted with methanol after the heat treatment. The extracts were analyzed using UV spectroscopy, high performance liquid chromatography (HPLC)-fluorescence/UV, ultra-performance liquid chromatography (UPLC)-photodiode array (PDA), and electrospray ionization-tandem quadrupole-mass spectrometry (ESI-TQDMS). The solid residues were analyzed using Fourier-transform infrared spectroscopy (FTIR). The UV and FTIR spectra of the AfB1-sm clay residue extracts obtained after heating had decreased AfB1 peak intensities and shifted peak positions with increased heating temperature. Significant shifts in band positions and changes in the shape of the UV spectra were observed in the extracts from the AfB1-Ca-sm complex heated at 175°C, the AfB1-Cu-sm complex heated at 150°C, and the AfB1-Mn-sm complex heated at 125°C. The HPLC and UPLCMS analyses of AfB1-sm complex extracts indicated a gradual decrease in AfB1 concentration with increased heating temperature and the formation of aflatoxins B2, B2a, M1, M2, and other unidentified compounds. No new compound was observed in the extracts of pure aflatoxin B1 after a comparable heating experiment. These results suggest that smectite can effectively convert aflatoxin to other less toxic forms at elevated temperatures. Smectite ion exchange with Cu or Mn transition-metal cations and heat treatment induced more efficient conversion of the adsorbed aflatoxin B1 molecules to other compounds.

Determination of 8 Synthetic Food Dyes by Solid Phase Extraction and Reversed-Phase High Performance Liquid Chromatography

Purpose: To develop a simple, selective, and sensitive extraction and assay method for the analysis of eight food dyes. Methods: All sulphonated colors were extracted by an NH2-aminopropyl-modified silica SPE cartridge, and thereafter determined by reverse phase high performance liquid chromatography (RP-HPLC) using a C18 column with gradient elution of ammonium acetate buffer (pH 6.7), methanol, and acetonitrile. The analysis was carried out on a UV detector with two optimized method settings within 17 min. Results: Certificated standard material (CRM) was used to validate the method, and significant difference was not observed between the results and assigned values. Maximum LOD was 1.154 ppm at 250 nm for Brilliant blue, and 0.873 ppm for carmoisine. Recovery was 94.2 % for Brilliant blue in jelly powder. Conclusion: This method was successfully applied to determine colorants in various (30) water-soluble foods, including fruit flavored drinks, sugar confectionery, sweets, etc.

Rapid determination of trace polycyclic aromatic hydrocarbons in particulate matter using accelerated solvent extraction followed by ultra high performance liquid chromatography with fluorescence detection.

A method has been developed for the trace analysis of polycyclic aromatic hydrocarbons, which are known as persistent organic pollutants and ubiquitous constituents of fine particulate matter that causes growing airborne pollution. The method, which was especially for samples of airborne particulate matter less than 2.5 μm in diameter, utilized accelerated solvent extraction and ultra high performance liquid chromatography with fluorescence detector. Four principal parameters of accelerated solvent extraction were optimized to obtain maximum extraction efficiency. Using the established synergetic programs of gradient elution and fluorescence wavelength switching, a rapid separation was achieved in 6.56 min with good linearity for 15 polycyclic aromatic hydrocarbons (coefficient of determination above 0.999). The limits of detection ranged from 0.833 to 10.0 pg/m(3) . The precision of the method expressed as inter-day relative standard deviation ranged from 0.2 to 1%, which was calculated from nine repetitive measurements of 8.00 μg/L analytes. Average spiked recoveries ranged from 71.6 to 97.7%, with the exception of naphthalene. The rapid, sensitive, and accurate method can meet the pressing needs of health risk assessment and increasingly heavy daily tasks of air quality monitoring.

Determination of Phenolic Acids in Atriplex hortensis L. by Novel Solid-Phase Extraction and High-Performance Liquid Chromatography

ABSTRACTA novel offline solid-phase extraction high-performance liquid chromatography method is reported for the determination of phenolic acids in Atriplex hortensis L. Isolation of the analytes was performed by maceration followed by solid-phase extraction with hydrophilic–lipophilic balance cartridges. The chromatography was performed using C18 guard and analytical columns. The mobile phase was 0.08%, aqueous o-phosphoric acid and 40:60 water/acetonitrile with gradient eluation. The analytes were detected at 254 nm by an ultraviolet detector. Calibration equations were obtained by least squares with a linear dynamic range from 1.00 to 20.00 mg/L. The limits of detection and quantification were from 0.25 to 0.45 and 0.77 to 1.36 mg/L, respectively. The precision was characterized as the repeatability and intermediate precision with samples fortified at low, medium, and high concentrations. The accuracy was evaluated as the recovery. The developed method determined the presence of vanillic acid, syringic acid, and ferulic acid in A. hortensis with good accuracy and precision.

Evaluation on Extraction Conditions and HPLC Analysis Method for Ginsenosides in Panax ginseng

Background : A new extraction method-heated ultrasonic extraction was qualitatively and quantitatively analyzed for the extraction of major ginsenosides from ginseng extract; this new high-performance liquid chromatography (HPLC) method was compared with the official extraction method of Korean industrial standards and standard for health functional food. Methods and Results : Ginsenoside compounds were analyzed for 35 minutes by the new HPLC analysis method using a Halo® RP-Amide column. The new HPLC analysis method was validated by the measurement of intra-day and inter-day precision, accuracy, limit of detection (LOD), and limit of quantification (LOQ) of each ginsenoside. The correlation coefficients (r2) for the calibration curves of the ginsenoside compounds were over 0.9997 in terms of linearity. The heated ultrasonic extraction method using ultrasonication for 30 minutes at 50℃ yielded higher amount of ginsenosides than the extraction method of the Korean industrial standards owing to the enhancement of extraction efficiency. Conclusions : Compared to the other extraction methods, the heated ultrasonic extraction method yielded a higher amount of ginsenoside Rb1 than Rg1 index compounds for the quality evaluation of ginseng roots.

Home-made online hyphenation of pressurized liquid extraction, turbulent flow chromatography, and high performance liquid chromatography, Cistanche deserticola as a case study

Incompatibility between the conventional pressurized liquid extraction (PLE) devices and high performance liquid chromatography (HPLC) extensively hinders direct and green chemical analysis of herbal materials. Herein, a facile PLE module was configured, and then it was online hyphenated with HPLC via a turbulent flow chromatography (TFC) column. Regarding PLE module, a long PEEK tube (0.13×1000mm) was employed to generate desired pressure (approximately 13.0MPa) when warm acidic water (70°C) was delivered as extraction solvent at a high flow rate (2.5mL/min), and a hollow guard column (3.0×4.0mm) was implemented to hold crude materials. Effluent was collected from the outlet of PEEK tube, concentrated, and subjected onto HPLC coupled with hybrid ion trap-time of flight mass spectrometer to assess the extraction efficiency and also to profile the chemical composition of Cistanche deserticola (CD) that is honored as “Ginseng of the desert”. Afterwards, a TFC column was introduced to accomplish online transmission of low molecule weight components from PLE module to HPLC coupled with diode array detection, and two electronic 6-port/2-channel valves were in charge of alternating the whole system between extraction (0–3.0min) and elution (3.0–35.0min) phases. Quantitative method was developed and validated for simultaneous determination of eight primary phenylethanoid glycosides in CD using online PLE–TFC–HPLC. All findings demonstrated that the home-made platform is advantageous at direct chemical analysis, as well as time-, solvent-, and material-savings, suggesting a robust tool for chemical fingerprinting of herbs.

On-line SPE Using Ionic Liquid-Based Monolithic Column for the Determination of Antihypertensives in Human Plasma

A poly(ionic liquid-glycidylmethacrylate-co-ethyleneglycol dimethacrylate) monolithic column was prepared via in situ free-radical polymerisation and used as an on-line solid-phase extraction column. The obtained monolithic column was characterized by scanning electron microscopy, Fourier transform infrared spectrometer, nitrogen adsorption–desorption measurement, and mercury intrusion porosimetry, which showed a relatively uniform and porous structure. During the on-line solid-phase extraction–high performance liquid chromatography protocol, nifedipine, nitrendipine, and felodipine were separated efficiently from human plasma using a methanol–water linear gradient at a flow rate of 1.0 mL min−1. The extraction efficiency for the targets was satisfactory with no matrix interference. Under the optimized extraction conditions, the linear regression coefficient was >0.9973; precisions for inter- and intra-day assays presented as relative standard deviations were less than 7.29 %, and the accuracy and recovery was in the range of 96–105 and 90–106 %, respectively. As a result, the polymerization monolithic column exhibited high selectivity and good permeability, and it was feasible to be used as an on-line SPE column. Meanwhile, validation assays also demonstrated acceptable sensitivity and precision for simultaneous quantitative screening of nifedipine, nitrendipine, and felodipine in human plasma.

Geochemical interactions between iron and phenolics originated from peatland in Hani, China: implications for effective transport of iron from terrestrial systems to marine

Iron is a restrictive element for primary productivity in the oceans. The influence of dissolved organic matters as metal chelators on the bio-available iron input to the ocean has been widely reported. However, natural dissolved organic matters, especially the phenolics originated from peatlands and geochemical interactions with iron remains poorly understood. In this study, solid phase extraction-high performance liquid chromatography experiments were conducted to determine the vertical distributions of phenolic acids in different peat layers in Hani Peatland, China. Ten phenolic acids, including protocatechuic acid, p-hydroxybenzoic acid, gentisic acid, caffeic acid, etc. were detected. Simulation experiments of phenolics-Fe interactions under alkaline conditions (pH = 8.0 ± 0.1) indicated phenolic acids bearing either catechol or galloyl groups (such as protocatechuic acid, caffeic acid and gallic acid) could chelate iron to produce relatively stable phenolics-Fe complexes and therefore help to weaken its precipitation in the oxidative condition. In addition, the simulation experiments with artificial coastal waters demonstrated that this complexation could ensure that at least 25 % of the initial Fe load dissolve in coastal water, implying large part of dissolved iron in rivers draining from peatlands could be transported through the estuarine zones. Considering the wide distribution of peatlands globally, the higher concentration of Fe in peatlands, and the enhancement of marine organisms by Fe, the geochemical interactions between iron and phenolics originated from peatlands are of important significance to transport bio-available iron from terrestrial system to oceans.

Rapid extraction and determination of 25 bioactive constituents in Alpinia oxyphylla using microwave extraction with ultra high performance liquid chromatography with tandem mass spectrometry.

A novel and rapid microwave extraction and ultra high performance liquid chromatography with tandem mass spectrometry method was developed and validated for the simultaneous determination of 25 bioactive constituents (including two new constituents) in Fructus Alpinia oxyphylla. The optimized conditions of the microwave extraction was a microwave power of 300 W, extraction temperature of 80°C, solvent-to-solid ratio of 30 mL/g and extraction time of 8 min. Separation was achieved on a Waters ACQUITY UPLC(®) HSS C18 column (2.1 mm× 50 mm, 1.8 μm) using gradient elution with a mobile phase consisting of acetonitrile and 1 mM ammonium acetate at a flow rate of 0.2 mL/min. This is the first report of the simultaneous determination of 25 bioactive constituents in Fructus Alpinia oxyphylla by ultra high performance liquid chromatography with tandem mass spectrometry. The method was validated with good linearity, acceptable precision and accuracy. The validated method was successfully applied to determine the contents of 25 bioactive constituents in Fructus Alpinia oxyphylla from different sources and the analysis results were classified by hierarchical cluster analysis, which indicated the effect of different cultivation regions on the contents of constituents. This study provides powerful and practical guidance in the quality control of Alpinia oxyphylla and lays the foundation for further research of Alpinia oxyphylla.

Evaluation of graphene-based sorbent in the determination of polar environmental contaminants in water by micro-solid phase extraction-high performance liquid chromatography

A facile method of extraction using porous membrane protected micro-solid phase extraction (μ-SPE) with a graphene-based sorbent followed by high performance liquid chromatography–ultraviolet detector was developed. The reduced graphene oxide (r-GO) (1mg), synthesized from graphite oxide, was enclosed in a polypropylene bag representing the μ-SPE device, which was used for the extraction of estrogens such as estrone, 17β-estradiol, 17α-ethynylestradiol and diethylstilbestrol in water. The r-GO obtained was identified and characterized by Fourier transform infrared, transmission electron microscopy, scanning electron microscopy and thermogravimetric analysis. The sorbent was loaded with sodium dodecyl sulfate by sonication to prevent agglomeration in aqueous solution. With this method, low limits of detection of between 0.24 and 0.52ngL−1 were achieved. For estrogen analysis a linear calibration range of 0.01–100μgL−1 was obtained, with the coefficients of determination (r2) higher than 0.992. This proposed method was successfully applied to determine estrogens in water.

Determination of Microcystin-LR in Environmental Water by Magnetic Solid Phase Extraction-High Performance Liquid Chromatography

Abstract A rapid analytical method was established for the determination of trace amounts of microcystin (MC-LR) in environmental water samples by using magnetic solid phase extraction (MSPE) coupled with HPLC/UV based on a magnetic bentonite sorbent fabricated by solvothermal synthesis method. Several factors influencing the extraction efficiency of MC-LR, such as sorbent amount, pH condition, sample volume, adsorption and desorption time, and desorption solvent, were investigated and optimized. Under the optimal extraction conditions, the limits of detection and quantification for the method were 0.75 and 1.5 ng L −1 , respectively, which was far below the guideline recommended by the World Health Organisation. The method showed a good linearity ( R 2 = 0.9993) in the concentration ranges of 0.25–250 μg L −1 for MC-LR. The MSPE sorbent was simple in preparation, low cost and magnetizable, and the developed MSPE-HPLC method was suitable for the rapid and sensitive determination of MC-LR in nature water samples.

Development of coupled supercritical fluid extraction-high performance liquid chromatography for quinone analysis in activated sludge

ABSTRACTCoupled supercritical fluid extraction-high performance liquid chromatography (Coupled SFE-HPLC) was developed to determine the microbial community dynamics based on the quinone profile. It is a fast (less than 2 h) and high reproducibility (1.6% in coefficient of variation) method. The comparable results were obtained by the developed method and the organic solvent extraction method, it was 603.4 µmol kg−1 and 594.1 µmol kg−1 dry samples, respectively. The low dissimilarity index (0.07) between the two methods indicates that quinone profile obtained by both methods were considered similar. The results show that coupled SFE-HPLC method offers simplification for a rapid and routine analysis.