Quantitative determination of chlorogenic acid in Honeysuckle using microwave-assisted extraction followed by nano-LC-ESI mass spectrometry

The chlorogenic acid (CA) in Honeysuckle is determined and identified by nano-liquid chromatography-electrospray ionization mass spectrometry (nano-LC-ESI/MS) after extraction with microwave-assisted extraction (MAE). As a new sample preparation method for Honeysuckle, the MAE procedure is optimized, validated and compared with conventional methods including reflux extraction (RE) and ultrasonic extraction (USE). It is found that MAE gives the best result due to the highest extraction efficiency within shortest extraction time (only 4 min). Here, CA is determined by nano-LC-ESI/MS based on the calibration curve of its authentic standard. The method linearity, detection limit, precision and recovery are studied. The results show that the combined MAE and nano-LC-ESI/MS method has a linearity (R² 0.991, 0.8-20 ng mL⁻¹), a low limit of detection (0.5 ng mL⁻¹), good precision (R.S.D. = 2.54%) and a recovery (84.8%). The experiment has demonstrated that the nano-LC-ESI/MS following MAE is a fast and reliable method for quantitative analysis of CA in Honeysuckle.     

Fast determination of chlorogenic acid in tobacco residues using microwave-assisted extraction and capillary zone electrophoresis technique

In this work, for the first time, capillary zone electrophoresis (CZE) technique combined with microwave-assisted extraction (MAE) was developed for the fast quantification of chlorogenic acid (CA) in tobacco residues. CA in tobacco residue samples were extracted by MAE technique, and then analyzed by CZE. As a new sample preparation method for tobacco residues, the MAE procedure is optimized, validated and compared with conventional methods including ultrasonic extraction (USE) and reflux extraction (RE). It is found that MAE gives the best result due to the highest extraction efficiency within shortest extraction time (only 4.0 min). Here, CA is determined by CZE based on the calibration curve of its authentic standard. The method linearity, detection limit, precision and recovery are studied. The results show that the combined MAE and CZE method has a linearity (R² 0.991, 0.003-0.5 mg ml⁻¹), a limit of detection (0.003 mg ml⁻¹), a limit of quantification (0.01 mg ml⁻¹), good precision (R.S.D. = 4.28%) and a finer recovery (89.0%). The proposed method was successfully applied to the analysis of CA in tobacco residue samples. The experiment results have demonstrated that the CZE combined with MAE is a convenient, fast, economical and reliable method for the determination of CA in tobacco residues.     

Determination of metabolites in Uncaria sinensis by HPLC and GC-MS after green solvent microwave-assisted extraction

Uncaria sinensis (Oliv.) Havil (Rubiaceae) has been used as an important Traditional Chinese Medicine (TCM) herb for the treatment of fevers and various nervous disorders. The major bioactive secondary metabolites from different classes of chemical compounds, i.e. organic acid, flavonoid and alkaloid, present in this TCM herb, namely catechin, caffeic acid, epicatechin and rhynchophylline, were extracted by microwave-assisted extraction (MAE) method with ultra-pure water as the extraction solvent. The optimal extraction conditions for this green solvent MAE method were found to be 100 °C for 20 min. The recoveries of the compounds were found to be comparable to that of heating under reflux using ultra-pure water for 60 min. The method precision (RSD, n = 6) was found to vary from 0.19% to 5.60% for the proposed method on different days for the secondary metabolites. Simultaneously, the key primary metabolites such as sucrose and phenylalanine for the biosynthesis of bioactive secondary metabolites were successfully characterized by GC-MS. Furthermore, an approach using the combination of primary and secondary metabolite profiling based on their chemical fingerprints with Principal Component Analysis (PCA) was successfully developed to evaluate the quality of U. sinensis obtained from different sources. This approach was shown to be feasible in discriminating U. sinensis from different origins and thus a potential application for the quality control of other medicinal herbs.     

Optimization of a microwave-assisted extraction of secondary metabolites from crustose lichens with quantitative spectrophotodensitometry analysis

A focused and rapid microwave-assisted extraction (MAE) process was carried out and optimized for secondary metabolites from crustose lichens using Taguchi experimental design and quantitative analysis on TLC by a Camag^® spectrophotodensitometer. The procedure was improved by quantitative determination of norstictic acid (NA), a common depsidone isolated from Pertusaria pseudocorallina (Sw.) Arn. Various experimental parameters that can potentially affect the NA extraction yields including extraction time, irradiation power, volume and the percentage of tetrahydrofuran (THF) were optimized. Results suggest that THF percentage and solvent volume were statistically the most significant factors. The optimal conditions were determined as follows: THF level of 100%, solvent volume of 15 mL, microwave power of 100 W and extraction time of 7 min. Compared to the reflux method, MAE showed a drastic reduction of extraction time (7 min vs. 3 h) and solvent consumption (15 mL vs. 30 mL). The NA in total yield was 90% using the two methods. The optimal conditions were applied to other crustose lichens, Aspicilia radiosa, Diploicia canescens and Ochrolechia parella for the extraction of NA, diploicine (DP) and variolaric acid (VA), with 83%, 90% and 95% of recovery, respectively.     

Optimization and validation of a low temperature microwave-assisted extraction method for analysis of polycyclic aromatic hydrocarbons in airborne particulate matter

A low temperature microwave-assisted extraction method (MAE) is reported for the analysis of polycyclic aromatic hydrocarbons (PAHs) in airborne particulate matter (PM). The main parameters affecting the extraction efficiency (choice of extractants, microwave power, and extraction time) were investigated and optimized. The optimized procedure requires a 20 ml mixture of acetone:n-hexane (1:1) for extraction of PAHs in PM at 150 W of microwave energy (20 min extraction time). Clean-up of MAE extracts was not found to be necessary. The optimized method was validated using two different SRM (1648-urban particulate matter and 1649a, urban dust). The results obtained are in good agreement with certified values. PAHs recoveries for both reference materials were between 79 and 122% with relative standard deviation ranging from 3 to 21%. Detection limits were determined based on blank determination using two kinds of quartz filter substrates (n = 10), which ranged from 0.001 (0.03) ng m⁻³ (pg/μg) for B(k)Ft to 1.119 (37.3) for Naph in ng m⁻³ (pg/μg), respectively. The repeatability and day-to-day reproducibility obtained in this study were in the range of 4-16 and 3-25% for spiked standards and SRM 1649, respectively. The optimized and validated MAE technique was applied to the extraction of PAHs from a set of real world PM samples collected in Singapore. The sum of particulate-bound PAHs in outdoor PM ranged from 1.05 to 3.45 ng m⁻³ while that in indoor PM (cooking emissions) ranged from 27.6 to 75.7 ng m⁻³, respectively.     

Determination of senkirkine and senecionine in Tussilago farfara using microwave-assisted extraction and pressurized hot water extraction with liquid chromatography tandem mass spectrometry

Tussilago farfara (Kuan Donghua) is an important Chinese herbal medicine which has been shown to contain many bioactive compounds and widely used to relieve cough and resolve phlegm. However, besides therapeutic bioactive compounds, this herb has been found to contain toxic pyrrolizidine alkaloids (PAs), mainly senkirkine and traces of senecionine. In this report, conditions for microwave-assisted extraction (MAE) and pressurized hot water extraction (PHWE) were optimized for the extraction of the PAs. The results were compared against heating under reflux. It was found that the binary mixture of MeOH:H₂O (1:1) acidified using HCl to pH 2-3 was the optimal solvent for the extraction of the PAs in the plant materials. Liquid chromatography (LC) with ultra-violet (UV) detection and electrospray ionization mass spectrometry (ESI-MS) in the positive mode was used for the determination and quantitation of senkirkine and senecionine in the botanical extract. The proposed extraction methods with LC/MS allow for the rapid detection of the major and the minor alkaloids in T. farfara in the presence of co-eluting peaks. With LC/MS, the quantitative analysis of PAs in the extract was done using internal standard calibration and the precision was found to vary from 0.6% to 5.4% on different days. The limits of detection (LODs) and limits of quantitation (LOQs) for MAE and PHWE were found to vary from 0.26 μg/g to 1.04 μg/g and 1.32 μg/g to 5.29 μg/g, respectively. The method precision of MAE and PHWE were found to vary from 3.7% to 10.4% on different days. The results showed that major and minor alkaloids extracted using MAE and PHWE were comparable to that by heating under reflux. Our data also showed that significant ion suppression was not observed in the analysis of senkirkine and senecionine in the botanical extracts with co-eluting peaks.     

Rapid method for simultaneous determination of flavonoid,saponins and polyacetylenes in Folium Ginseng and Radix Ginseng by pressurized liquid extraction and high-performance liquid chromatography coupled with diode array detection and mass spectrometry

A rapid pressurized liquid extraction (PLE) and high-performance liquid chromatography coupled with diode array detection and mass spectrometry (HPLC-DAD–MS) method for the simultaneous determination of one flavonoid (panasenoside), nine saponins (ginsenoside Rg1, Re, Rf, Rg2, Rb1, Rc, Rb2, Rb3 and Rd) and two polyacetylenes (panaxydol and panaxynol) in Folium Ginseng and Radix Ginseng was developed. A Prevail C₁₈ rocket column (33 mm × 7 mm, 3.0 μm) and gradient elution were used during the analysis. Flavonoid was quantified at 355 nm, and saponins and polyacetylenes were determined at 203 nm. The chromatographic peaks of 12 investigated compounds in samples were unambiguously identified by compared their UV spectra and/or MS data with the related reference compounds. All calibration curves showed good linearity (r > 0.999) within the test ranges. The intra- and inter-day variations for 12 analytes were less than 1.17% and 2.17%, respectively. The developed method was successfully applied to determine the investigated compounds in 10 samples of Radix Ginseng and Folium Ginseng, respectively. The result showed that PLE combined with rocket column HPLC analysis could provide a rapid method for analysis of compounds in traditional Chinese medicines (TCMs), which is helpful to comprehensive evaluation of quality of Radix Ginseng and Folium Ginseng.     

Temperature-assisted ionic liquid dispersive liquid-liquid microextraction combined with high performance liquid chromatography for the determination of anthraquinones in Radix et Rhizoma Rhei samples

In this article, a novel method termed as temperature-assisted ionic liquid dispersive liquid-liquid microextraction (TA IL-DLLME) combining high performance liquid chromatography with diode array detection (HPLC-DAD) was developed for the determination of anthraquinones in Radix et Rhizoma Rhei samples. The ionic liquid (1-hexyl-3-methylimidazolium hexafluorophosphate) was used to replace volatile organic solvent as an extraction solvent for the extraction of anthraquinones (aloe-emodin, rhein, emodin, chrysophanol and physcion) from Radix et Rhizoma Rhei. Several important parameters influencing the extraction efficiency of TA IL-DLLME such as the type and volume of extraction solvent and disperser solvent, sample pH, extraction time, extraction temperature, centrifugation time as well as salting-out effects were optimized. Under the optimal conditions, the spiked recovery for each analyte was in the range of 95.2-108.5%. The precisions of the proposed method were varied from 1.1% to 4.4% (RSD). All the analytes exhibited good linearity with correlation coefficients (r²) ranging from 0.9986 to 0.9996. The limits of detection for all target analytes were ranged from 0.50 to 2.02 μg L⁻¹ (S/N = 3). The experimental results indicated that the proposed method was successfully applied to the analysis of anthraquinones in Radix et Rhizoma Rhei.     

Combined microwave-assisted isolation and solid-phase purification procedures prior to the chromatographic determination of phenolic compounds in plant materials

A fast, sensitive and selective procedure employing a combination of microwave-assisted extraction (MAE) and solid phase extraction (SPE) was applied prior to liquid chromatographic identification and quantification of phenolic compounds in plant materials. MAE has been tested and optimized for the isolation of phenolic acids (gallic, protocatechuic, p-hydroxybenzoic, chlorogenic, vanilic, caffeic, syringic, p-coumaric, ferulic, sinapic, benzoic, m-coumaric, o-coumaric, rosmarinic, cinnamic acids) and 3,4-dihydroxybenzaldehyde, syringaldehyde, p-hydroxybenzaldehyde, and vanillin in various plants. The effects of experimental conditions on MAE efficiency, such as solvent composition, temperature, extraction time, have been studied. The extraction efficiencies were compared with those obtained by computer-controlled, two-step Soxhlet-like extractions. Plant extracts were purified and phenolic compounds were pre-concentrated using SPE on polymeric RP-105 SPE sorbent prior to HPLC analysis. Chromatographic separation was carried out on a Hypersil BDS C₁₈ column using a mobile phase consisted of 0.3% (v/v) acetic acid in water (solvent A) and methanol (solvent B) at flow rate 0.6 ml min⁻¹ and column temperature 30 °C with gradient elution.     

Application of ionic liquids based microwave-assisted extraction of three alkaloids N-nornuciferine, O-nornuciferine, and nuciferine from lotus leaf

The application of ionic liquids based microwave-assisted extraction (ILMAE) was successfully developed for extracting three alkaloids N-nornuciferine, O-nornuciferine, and nuciferine from lotus leaf. Seven kinds of 1-alkyl-3-methylimidazolium with different cations and anions were investigated in this work and 1.0 M 1-hexyl-3-methylimidazolium bromide ([C₆MIM]Br) solution was selected as solvent. In addition, the microwave parameters including irradiation power, extraction time and solid-liquid ratio were optimized. Compared with the regular MAE and conventional heat-reflux extraction (HRE), the proposed approach exhibited higher efficiency (0.9-43.7% enhanced) and shorter extraction time (from 2 h to 2 min), which indicated ILMAE was an efficient, rapid and simple sample preparation technique. Moreover, the proposed method was validated by the linearity, reproducibility, and recovery experiments. Good linearity was observed with the regression coefficients (r²) between 0.9998 and 0.9999. The recoveries of all methods were in the range of 94.6% and 105.5% with RSD lower than 6.6%, which indicated that the proposed method was credible.     

Simultaneous analysis and retention behavior of major isoflavonoids in Radix Puerariae lobatae and Radix Puerariae thomsonii by high performance liquid chromatography with cyclodextrins as a mobile phase modifier

In order to differentiate two species of Radix Puerariae (Radix Puerariae lobatae and Radix Puerariae thomsonii) and to determine major isoflavonoids (puerarin, daidzin, daidzein and genistein) in the samples, a simple high performance liquid chromatography (HPLC) method with isocratic elution employing cyclodextrins (CDs) as mobile phase additives was developed. Various factors affecting the retention of isoflavonoids in the C₁₈ reversed-phase column, such as the nature of CDs, the concentration of hydroxypropyl-β-cyclodextrin (HP-β-CD) and the methanol percentage in the mobile phase, were studied. Experimental results confirmed that HP-β-CD, as a very effective mobile phase additive, could markedly reduce the retention of isoflavonoids, especially daidzein and genistein. The elution of four isoflavonoids could be achieved on a Kromasil^® C₁₈ column within 56 min by using the methanol–water contained 5 mM HP-β-CD (25/75, v/v) mixture as the mobile phase. The formation of the inclusion complexes between isoflavonoids and HP-β-CD explained the modification of the retention of analytes. The apparent formation constants determined by HPLC confirmed that the stoichiometry of HP-β-CD-isoflavonoid complexes was 1:1, and the stability of the complexes depended on the size and property of isoflavonoids. The optimized method was successfully applied for the simultaneous determination of major isoflavonoids in P. lobatae and P. thomsonii samples. This work provides a useful method for the analysis of traditional Chinese herbs.     

Microwave-assisted extraction of scutellarin from Erigeron breviscapus Hand-Mazz and its determination by high-performance liquid chromatography

An efficient microwave-assisted extraction (MAE) technique has been developed to extract scutellarin from Erigeron breviscapus for rapid determination by high-performance liquid chromatography (HPLC). The maximum yield of scutellarin reached 1.02% in 40 min under the optimal MAE conditions with 80 °C of extraction temperature and 1:10 (w/v) of the solid/liquid ratio. The MAE showed obvious advantages in terms of short duration and high efficiency to extract scutellarin in comparison with heat-flux extraction. The mechanism of the enhanced extraction by microwave assistance was discussed by detecting particle size and specific surface area of plant materials and observing cell destruction of plant material by light microscopy and scanning electron microscopy. The results showed that the plant materials were significantly destroyed due to the cell rupture after MAE treatment. Afterward, the method validation for HPLC-UV analysis was developed. Calibration range was 0.1-100 μg mL⁻¹ for scutellarin, and correlation coefficient R was 0.9993. Limit of detection was less than 0.01 μg mL⁻¹. The intra- and inter-day relative standard deviation (R.S.D.) of scutellarin detection ranged from 1.58% to 2.96% and from 3.32% to 4.19%, respectively. The recovery of the method for scutellarin ranged from 96.7% to 101.9%.     

Simple and sensitive monitoring of sulfonamide veterinary residues in milk by stir bar sorptive extraction based on monolithic material and high performance liquid chromatography analysis

A simple, rapid, and sensitive method for the quantitative monitoring of five sulfonamide antibacterial residues (SAs) in milk was developed by stir bar sorptive extraction (SBSE) coupling to high performance liquid chromatography with diode array detection. The analytes were concentrated by SBSE based on poly (vinylimidazole–divinylbenzene) monolithic material as coating. The extraction procedure was very simple, milk was diluted with water then directly sorptive extraction without elimination of fats and protein in samples was required. To achieve optimum extraction performance for SAs, several parameters, including extraction and desorption time, desorption solvent, ionic strength and pH value of sample matrix were investigated. Under the optimized experimental conditions, low detection limits (S/N = 3) quantification limits (S/N = 10) of the proposed method for the target compounds were achieved within the range of 1.30–7.90 ng/mL and 4.29–26.3 ng/mL from spiked milk, respectively. Good linearities were obtained for SAs with the correlation coefficients (R²) above 0.996. Finally, the proposed method was successfully applied to the determination of SAs compounds in different milk samples and satisfied recoveries of spiked target compounds in real samples were obtained.     

A vascular smooth muscle/cell membrane chromatography–offline-gas chromatography/mass spectrometry method for recognition,separation and identification of active components from traditional Chinese medicines

We describe an analytical method of vascular smooth muscle cell membrane chromatography (VSM/CMC) combined with gas chromatography/mass spectrometry (GC/MS) for recognition, separation and identification of active components from traditional Chinese medicines (TCMs). VSM cells by means of primary culture with rat thoracic aortas were used for preparation of the stationary phase in the CMC model. Retention components by the VSM–CMC model were collected and then analyzed by GC/MS under the optimized conditions in offline conditions. After investigating the suitability and reliability of the VSM/CMC–offline-GC/MS method using nifedipine and nitrendipine as standard compounds, this method was applied in screening active components from the extracts of TCMs such as Radix Angelicae Dahuricae (RAD), Rhizomza Seu Radix Notopterygii (RSRN), Radix Glehniae (RG) and Fructus Cnidii (FC). Retention components from the extracts in the VSM–CMC model were imperatorin and osthole identified by the GC/MS method. In vitro pharmacological trials indicated that imperatorin and osthole could concentration dependently relax the rat thoracic artery pre-contracted by KCl (P < 0.05). The maximum relaxation effects (R_max) were 63 ± 5% and 40 ± 6% for imperatorin and osthole, respectively. The VSM/CMC–offline-GC/MS method is an effective screening system that can rapidly detect and enrich target components from a complex sample and then accurately identify them.     

Microwave‐assisted extraction with water for fast extraction and simultaneous RP‐HPLC determination of phenolic acids in Radix Salviae Miltiorrhizae

An optimized microwave‐assisted extraction method using water (MAE‐W) as the extractant and an efficient HPLC analysis method were first developed for the fast extraction and simultaneous determination of D (+)‐(3,4‐dihydroxyphenyl) lactic acid (Dla), salvianolic acid B (SaB), and lithospermic acid (La) in Radix Salviae Miltiorrhizae. The key parameters of MAE‐W were optimized. It was found that the degradation of SaB was inhibited when using the optimized MAE‐W and the stable content of Dla, La, and SaB in danshen was obtained. Furthermore, compared to the conventional extraction methods, the proposed MAE‐W is a more rapid method with higher yield and lower solvent consumption with a reproducibility (RSD <6%). In addition, using water as extractant is safe and helpful for environment protection, which could be referred to as green extraction. The separation and quantitative determination of the three compounds was carried out by a developed reverse‐phase high‐performance liquid chromatographic (RP‐HPLC) method with UV detection. Highly efficient separation was obtained using gradient solvent system. The optimized HPLC analysis method was validated to have specificity, linearity, precision, and accuracy. The results indicated that MAE‐W followed by HPLC–UV determination is an appropriate alternative to previously proposed method for quality control of Radix Salviae Miltiorrhizae.     

Rapid analysis of Radix puerariae by near-infrared spectroscopy

A new, rapid analytical method using near-infrared spectroscopy (NIRS) was developed to differentiate two species of Radix puerariae (GG), Pueraria lobata (YG) and Pueraria thomsonii (FG), and to determine the contents of puerarin, daidzin and total isoflavonoid in the samples. Five isoflavonoids, puerarin, daidzin, daidzein, genistin and genistein were analyzed simultaneously by high-performance liquid chromatography-diode array detection (HPLC-DAD). The total isoflavonoid content was exploited as critical parameter for successful discrimination of the two species. Scattering effect and baseline shift in the NIR spectra were corrected and the spectral features were enhanced by several pre-processing methods. By using linear discriminant analysis (LDA) and soft independent modeling class analogy (SIMCA), samples were separated successfully into two different clusters corresponding to the two GG species. Furthermore, sensitivity and specificity of the classification models were determined to evaluate the performance. Finally, partial least squares (PLS) regression was used to build the correlation models. The results showed that the correlation coefficients of the prediction models are R = 0.970 for the puerarin, R = 0.939 for daidzin and R = 0.969 for total isoflavonoid. The outcome showed that NIRS can serve as routine screening in the quality control of Chinese herbal medicine (CHM).     

Development of microwave-assisted extraction followed by headspace solid-phase microextraction and gas chromatography-mass spectrometry for quantification of camphor and borneol in Flos Chrysanthemi Indici

In the work, microwave-assisted extraction (MAE) followed by headspace solid-phase microextraction (HS-SPME) and gas chromatography-mass spectrometry (GC-MS) was developed for quantitative analysis of the bioactive components of camphor and borneol in a traditional Chinese medicines (TCM) of Flos Chrysanthemi Indici. After systematical investigation, the optimal experimental parameters microwave power (400 W), irradiation time (4 min), fiber coating (PDMS/DVB fiber), extraction temperature (40 °C), extraction time (20 min), stirring rate (1100 rpm), and salt effect (no salt added) were investigated. The optimized method provided satisfactory precision (RSD values less than 12%), good recovery (from 86% to 94%), and good linearity (R² > 0.999). The proposed method was applied to quantitative analysis of camphor and borneol in Flos Chrysanthemi Indici samples from 11 different growing areas. To demonstrate the method feasibility, steam distillation was also used to analyze camphor and borneol in Flos Chrysanthemi Indici samples from these different growing areas. The very close results were obtained by the two methods. It has been shown that the proposed ME-HS-SPME-GC-MS is a simple, rapid, solvent-free and reliable method for quantitative analysis of camphor and borneol in TCM, and a potential tool for quality assessment of Flos Chrysanthemi Indici.     

Preparation and characterization of metal-organic framework MIL-101(Cr)-coated solid-phase microextraction fiber

Metal-organic frameworks (MOFs) have received great attention as novel sorbents due to their fascinating structures and intriguing potential applications in various fields. In this work, a MIL-101(Cr)-coated solid-phase microextraction (SPME) fiber was fabricated by a simple direct coating method and applied to the determination of volatile compounds (BTEX, benzene, toluene, ethylbenzene, m-xylene and o-xylene) and semi-volatile compounds (PAHs, polycyclic aromatic hydrocarbons) from water samples. The extraction and desorption conditions of headspace SPME (HS-SPME) were optimized. Under the optimized conditions, the established methods exhibited excellent extraction performance. Good precision (<7.7%) and low detection limits (0.32–1.7 ng L⁻¹ and 0.12–2.1 ng L⁻¹ for BTEX and PAHs, respectively) were achieved. In addition, the MIL-101(Cr)-coated fiber possessed good thermal stability, and the fiber can be reused over 150 times. The fiber was successfully applied to the analysis of BTEX and PAHs in river water by coupling with gas chromatography–mass spectrometry (GC–MS). The analytes at low concentrations (1.7 and 10 ng L⁻¹) were detected, and the recoveries obtained with the spiked river water samples were in the range of 80.0–113% and 84.8–106% for BTEX and PAHs, respectively, which demonstrated the applicability of the self-made fiber.     

Determination of various estradiol mimicking-compounds in sewage sludge by the combination of microwave-assisted extraction and LC-MS/MS

In this work, we present the development and application of a microwave assisted extraction followed by liquid chromatography-tandem mass spectrometry methodology (MAE-LC-MS/MS) for the determination of various estradiol-mimicking compounds in sewage sludge samples. For the purification of the MAE extracts, we have employed a solid phase extraction (SPE) clean-up procedure, previously optimised. The entire method provides recoveries between 71.7% and 103.1%, with relative standard deviation lower than 11.1% and limits of detection ranging from 0.6 to 3.5 ng g⁻¹. The developed method was applied to samples from three wastewater treatment plants (WWTPs) located in Las Palmas of Gran Canaria (Spain), two of which had a conventional activated sludge treatment (AST), whereas the third treatment plant had an advanced membrane bioreactor treatment (MBR). All of the analytes in the study, including (nonylphenol (NP), octylphenol (OP), and some of their ethoxylated chains AP_nEOs (n ≤ 7), 17β-estradiol (E2), estriol (E3), 17α-ethynylestradiol (EE) and bisphenol-A (BPA)), were found in almost all samples in concentrations ranging from 0.9 to 710.2 ng g⁻¹.     

An accurate and precise high-performance liquid chromatography method for the rapid quantification of the novel HIV integrase inhibitor raltegravir in human blood plasma after solid phase extraction

The quantification of the HIV integrase inhibitor raltegravir in blood plasma is described using solid phase extraction (SPE) coupled with an accurate high-performance liquid chromatography assay with ultraviolet (UV) detection. The method was validated over the range of 20-10,000 ng/mL using simple sample preparation and chromatography. The SPE method was optimized to be selective and highly efficient. The buffer’s ionic strength and pH were optimized for retaining RAL and the internal standard on the column, the percentage of methanol was optimized in the cleaning step to remove unwanted plasma contaminants, and the type and amount of acid was optimized for complete elution of the compounds. This method has no interference with other potentially co-administered antiretrovirals or common drugs. Average recoveries for the extraction method were consistently high: 90% for raltegravir and 90% for the internal standard diazepam. This method was found to be accurate and precise. Within day (n = 6) and between day (n = 18) accuracies ranged from 97.5 to 104.4%. Within-day (n = 6) and between-day (n = 18) precision ranged from 1.4 to 3.8%, and from 2.4 to 7.9%, respectively. This is the first published method to use simple UV technology and reliable SPE extraction methodology for the quantification of raltegravir in human plasma. This method can be easily implemented in most bioanalytical laboratories.