Volume Injection-gas Chromatography-mass Spectrometry Research Articles

Drugs, pesticides and metabolites in forensic post-mortem blood samples.

Forensic post-mortem toxicological data provide valuable information for the elucidation of cause of death. However, this is still not routine practice in Brazilian laboratories. This study investigated the presence of illicit and prescription drugs, pesticides and metabolites in 111 post-mortem blood samples from cases investigated by the Forensic Medical Institute of the Federal District, Brazil. Quantitative analysis was performed for 14 analytes using a validated programmed temperature vaporisation-large volume injection-gas chromatography-mass spectrometry method, which was also used as screening (qualitative analysis) for an additional 19 substances of forensic interest. At least one analyte was found in 61.2% of the samples, of which 34 were related to homicide, 15 to accidental death and 10 to suicide cases. The victims were 14-72 years old. The benzodiazepines diazepam, midazolam and 7-aminoflunitrazepan were detected in 46% of the positive samples (0.02-1.12 µg/mL; midazolam only qualitative). Cocaine was found in 34% (0.02-4.07 µg/mL), associated with substances commonly used as cocaine adulterants (e.g. caffeine, lidocaine and phenacetin). Three suicide cases involved the illegal rodenticide chumbinho, residues of which were found in the gastric content, and blood samples showed the presence of terbufos (0.03 and 0.04 µg/mL) and carbofuran (27.3 µg/mL). These results are discussed, along with autopsy and crime-scene information.

A Fast and Validated High Throughput Bar Adsorptive Microextraction (HT-BAµE) Method for the Determination of Ketamine and Norketamine in Urine Samples.

We developed, optimized and validated a fast analytical cycle using high throughput bar adsorptive microextraction and microliquid desorption (HT-BAμE-μLD) for the extraction and desorption of ketamine and norketamine in up to 100 urine samples simultaneously, resulting in an assay time of only 0.45 min/sample. The identification and quantification were carried out using large volume injection-gas chromatography-mass spectrometry operating in the selected ion monitoring mode (LVI-GC-MS(SIM)). Several parameters that could influencing HT-BAµE were assayed and optimized in order to maximize the recovery yields of ketamine and norketamine from aqueous media. These included sorbent selectivity, desorption solvent and time, as well as shaking rate, microextraction time, matrix pH, ionic strength and polarity. Under optimized experimental conditions, suitable sensitivity (1.0 μg L−1), accuracy (85.5–112.1%), precision (≤15%) and recovery yields (84.9–105.0%) were achieved. Compared to existing methods, the herein described analytical cycle is much faster, environmentally friendly and cost-effective for the quantification of ketamine and norketamine in urine samples. To our knowledge, this is the first work that employs a high throughput based microextraction approach for the simultaneous extraction and subsequent desorption of ketamine and norketamine in up to 100 urine samples simultaneously.

Evaluation of α- and β-Endosulfan Residues in Teas and Yerba Mate Infusions by Bar Adsorptive Microextraction and Large Volume Injection-Gas Chromatography Mass Spectrometry

Tea and yerba mate are traditional beverages prepared through the infusion of leaves of Camellia sinensis and Ilex paraguariensis, respectively. During this process, the leaching of pesticides onto the beverage, such as endosulfan, may occur. In this study, a bar adsorptive microextraction (BAµE) method prior to large gas chromatography mass spectrometry analysis was developed to analyze a- and b-endosulfan in teas and yerba mate infusions. Different sorbent coatings for BAµE were compared and the hydrophilic-lipophilic balanced polymer showed the best selectivity for endosulfan isomers. The method was validated providing good recoveries (varying from 80.4 ± 1.8 to 108 ± 4.9%) and linearities (r2 > 0.99), limits of detection from 8.0 to 4.0 µg kg-1 and limits of quantification from 40 to 20 µg kg-1 for a- and b-endosulfan, respectively. The application of the method in the analysis of real samples showed all free of endosulfan at the limit of detection of the analytical method.

High throughput bar adsorptive microextraction: A simple and effective analytical approach for the determination of nicotine and cotinine in urine samples

A simple, effective, convenient and environmentally friendly methodology using high throughput bar adsorptive microextraction (HT-BAμE) with microliquid desorption in combination with large volume injection-gas chromatography-mass spectrometry operating in the selected-ion monitoring acquisition mode (LVI–GC–MS(SIM)) was applied for the determination of nicotine and cotinine in urine samples. Under optimized experimental conditions, the developed methodology allowed for linear dynamic ranges between 20.0 and 2000.0 μg L-1 with determination coefficients of 0.9991 and 0.9992, as well as average recovery yields of 61.7–67.5% and 53.9–57.8% for nicotine and cotine, respectively. The developed methodology was applied to monitor urine samples from 86 volunteers having different smoking habits, where nicotine and cotinine were quantified in the range from 23.6 to 2612.6 μg L-1.The target compounds were extracted in a HT-BAμE apparatus, which allows for simultaneous microextraction and subsequent back-extraction of up to 100 samples. This is a major improvement over other microextraction techniques.The data from the proposed methodology were satisfactory and in line with current green analytical chemistry guidelines, and proved to be an effective sample preparation alternative with substantial potential for high throughput bioanalysis.

Dual-hollow fiber microextraction (dual-HFμE) - application for monitoring trace levels of organochlorine pesticides in real matrices

ABSTRACT In this contribution, the features and the advantages of the modified hollow fibre microextraction (HFµE) technique are discussed, by using two membranes (dual-HFµE) per sample, loaded with convenient organic solvents. The new approach proposed combined with micro-liquid desorption followed by large volume injection-gas chromatography-mass spectrometry operating in the selected-ion monitoring acquisition mode, [dual-HFμE-μLD/LVI-GC-MS(SIM)], was applied for trace analysis of 17 organochlorine pesticides (OCPs) in real matrices. By using dual-HFµE devices embedded with n-heptane and toluene (≈ 50 µL), fast kinetics (2 h) and selectivity enhancement were achieved to monitor 17 OCPs, particularly for the benzene hexachlorides, with convenient precision (RSD < 16%). Assays performed on 25 mL aqueous samples spiked with OCPs at the trace level yielded average recoveries between (40.6 ± 6.8) % and (101.7 ± 8.0) %, low detection limits (0.01–0.02 µg L−1), as well as good linear dynamic ranges (0.07–10.00 µg L−1) with suitable determination coefficients (r 2 > 0.9941). Through the standard addition method, the proposed methodology demonstrated good performance to monitor OCPs at the trace level in several types of matrices, including tap water, wastewater, soil, tea, and tomato samples. Besides the performance obtained and the wide applicability demonstrated, the dual-HFμE technique proved to be user-friendly, eco-friendly, cost-effective, and very competitive for routine work, being a remarkable alternative over other well-established microextraction techniques for trace analysis of priority and emerging compounds in real matrices.

Trace detection of explosives with a unique large volume injection gas chromatography-mass spectrometry (LVI-GC-MS) method

Highly sensitive splitless programmed temperature vaporizing (PTV)-large volume injection (LVI)-GC-MS-negative chemical ionization (NCI) method was developed and validated for the trace detection of explosives and related compounds from environmental matrices.

Off-line microextraction by packed sorbent combined with on solid support derivatization and GC-MS: Application for the analysis of five pyrethroid metabolites in urine samples

A novel, fast and eco-friendly analytical method using microextraction by packed sorbent coupled to large volume injection-gas chromatography-mass spectrometry (MEPS-LVI-GC-MS) was developed for the determination of five pyrethroid metabolites (cis-2,2-dimethyl-3-(2-chloro-3,3,3-trifluoro-1-propenyl)-cyclopropanecarboxylic acid, cis/trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane-1-carboxylic acids, cis-(2,2-dibromovinyl)-2,2-dimethylcyclopropane-1-carboxylic acid and 3-phenoxybenzoic acid) in human urine. MEPS was performed off-line using a manually-operated semiautomatic syringe (eVol), and several parameters including the sample pH, extraction sorbent, washing solvent, volume and type of elution solvent and number of draw-eject cycles were optimized. Analytes were extracted from enzymatically hydrolyzed urine using a C18 solid phase with subsequent simultaneous derivatization and elution with a mixture of 1,1,1,3,3,3-hexafluoroisopropanol and diisopropylcarbodiimide in n-hexane (on-line derivatization). The optimized method was validated, with linearity established from 0.05 to 25ngmL−1 and R values > 0.99. Obtained quantification limits were in the range of 0.06–0.08ngmL−1, and the precision expressed as relative standard deviation (RSD) was below 14% for all of the analytes. The method was cross-validated with a reference approach based on liquid-liquid extraction-gas chromatography-mass spectrometry (LLE-GC-MS) by analyzing 21 urine samples.

Dispersive liquid-liquid microextraction for the determination of nitrophenols in soils by microvial insert large volume injection-gas chromatography–mass spectrometry

A rapid and sensitive procedure for the determination of six NPs in soils by gas chromatography and mass spectrometry (GC–MS) is proposed. Ultrasound assisted extraction (UAE) is used for NP extraction from soil matrices to an organic solvent, while the environmentally friendly technique dispersive liquid-liquid microextraction (DLLME) is used for the preconcentration of the resulting UAE extracts. NPs were derivatized by applying an “in-situ” acetylation procedure, before being injected into the GC–MS system using microvial insert large volume injection (LVI). Several parameters affecting UAE, DLLME, derivatization and injection steps were investigated. The optimized procedure provided recoveries of 86–111% from spiked samples. Precision values of the procedure (expressed as relative standard deviation, RSD) lower than 12%, and limits of quantification ranging from 1.3 to 2.6ngg−1, depending on the compound, were obtained. Twenty soil samples, obtained from military, industrial and agricultural areas, were analyzed by the proposed method. Two of the analytes were quantified in two of the samples obtained from industrial areas, at concentrations in the 4.8–9.6ngg−1 range.

Analysis of polycyclic aromatic hydrocarbons in aqueous samples by large volume injection gas chromatography–mass spectrometry using the through oven transfer adsorption desorption interface

A new procedure for the determination of 17 polycyclic aromatic hydrocarbons (PAHs) in aqueous samples by large volume injection–gas chromatography–mass spectrometry (LVI–GC–MS) using the Through Oven Transfer Adsorption Desorption (TOTAD) interface with nitrogen for solvent elimination is developed and validated. Up to 75mL of aqueous samples were injected to be sure that good solvent elimination were achieved, although 500µL were sufficient to achieve the required sensitivity.The performance of the developed method can be considered good: the relative standard deviation (RSD), (n=3) was lower than 13.8% for all the target analytes, the concentration of each PAH being 0.25μgL−1, the limit of detection and limit of quantitation ranged from 21.5 to 211.0 ng L−1 and from 71.7 to 703.3ngL−1 respectively, and the correlation coefficients (R2) were all higher than 0.9764 in the 1–16μgL−1 range.

Determination of tributyltin in environmental water matrices using stir bar sorptive extraction with in-situ derivatisation and large volume injection-gas chromatography–mass spectrometry

Stir bar sorptive extraction with in-situ derivatization using sodium tetrahydridoborate (NaBH4) followed by liquid desorption and large volume injection-gas chromatography–mass spectrometry detection under the selected ion monitoring mode (SBSE(NaBH4)in-situ–LD/LVI-GC–MS(SIM)) was successfully developed for the determination of tributyltin (TBT) in environmental water matrices. NaBH4 proved to be an effective and easy in-situ speciation agent for TBT in aqueous media, allowing the formation of adducts with enough stability and suitable polarity for SBSE analysis. Assays performed on water samples spiked at the 10.0μg/L, yielded convenient recoveries (68.2±3.0%), showed good accuracy, suitable precision (RSD<9.0%), low detection limits (23ng/L) and excellent linear dynamic range (r2=0.9999) from 0.1 to 170.0µg/L, under optimized experimental conditions. By using the standard addition method, the application of the present methodology to real surface water samples allowed very good performance at the trace level. The proposed methodology proved to be a feasible alternative for routine quality control analysis, easy to implement, reliable and sensitive to monitor TBT in environmental water matrices.

Combination of programmable temperature vaporizer-large volume injection gas chromatography-mass spectrometry and automated mass spectral deconvolution and identification system for the determination of 32 pesticides in fruits and vegetables

An analytical method was developed for the simultaneous determination of 32 pesticides including organophosphorus, organochlorine, pyrethroid and carbamate pesticides in fruits and vegetables using gas chromatography-mass spectrometry (GC-MS). The sample was extracted with acetonitrile, and the organic layer was cleaned up with ENVI-Carb and LC-NH2 cartridges. A large volume of 20 µL purified solution was injected into the GC system using programmable temperature vaporizer (PTV). The mass spectrometric detection was operated with full scan mode. The automated mass spectral deconvolution and identification system (AMDIS) and an isotopic internal standard were used for the qualitative and quantitative determination of the 32 pesticides, respectively. The conditions for PTV-large volume injection were studied. Furthermore, the selectivity and durability of the method were also assessed. Under the optimized conditions, the experimental results showed that all the linearities were good within their test ranges, with correlation coefficients more than 0. 995, and the method detection limits of the pesticides were 2.0-5.0 µg/kg. The spiked recoveries (n=6) at three levels in the 0. 010 - 0. 50 mg/kg using spinach, snap bean and cucumber samples as blank matrices were in the range of 65. 2% - 120. 3% with the relative standard deviations (RSDs) varying from 4. 1% to 22. 3%, showing good accuracy of the method. The advantages of the proposed method include high throughput, high sensitivity, reliability, robustness, and the ability to meet the demand of multi-residue pesticide analysis in fruits and vegetables.

Improvements on bar adsorptive microextraction (BAμE) technique–Application for the determination of insecticide repellents in environmental water matrices

Bar adsorptive microextraction combined with micro-liquid desorption followed by large volume injection-gas chromatography-mass spectrometry operating in the selected-ion monitoring acquisition mode (BAµE-µLD/LVI-GC-MS(SIM)), is proposed for the determination of trace levels of three insecticide repellents (N,N-diethyl-meta-toluamide (DEET), cis and trans permethrin (PERM)) in environmental water matrices. By comparing different sorbent coatings (five activated carbons and six polymers) through BAµE, an activated carbon (AC2) proved to be the best compromise between selectivity and efficiency, even against polydimethylsiloxane through stir bar sorptive extraction. The novel improvement proposed on the back-extraction stage performed in a single step, by reducing the desorption solvent volume at the microliter level, demonstrated remarkable performance turning possible to save time, making easier the practical manipulation and more environmentally friendly. Assays performed by BAµE(AC2)-µLD/LVI-GC-MS(SIM) on 25 mL of ultrapure water samples spiked at the 1.0 μg/L level, yielded recoveries ranging from 73.8±8.8% (trans-PERM) to 96.4±9.9% (DEET), under optimised experimental conditions. The analytical performance showed convenient detection limits (8-20 ng/L) and good linear dynamic ranges (0.04-4.0 µg/L) with suitable determination coefficients (r(2)>0.9963, DEET). Excellent repeatability were also achieved through intraday (RSD<14.9%) and interday (RSD<11.9%) experiments. The novel improvement on downsizing the BAµE device to half-size proved to be either a promising option in forthcoming to reduce still more the desorption solvent volume without losing microextraction efficiency. By using the standard addition methodology, the application of the present analytical approach on tap, ground, river, swimming-pool and estuary water samples revealed good sensitivity at trace level and absence of matrix effects.

Linear and cyclic methylsiloxanes in air by concurrent solvent recondensation–large volume injection–gas chromatography–mass spectrometry

In the present work, a simple and fast method for the analysis of linear and cyclic methylsiloxanes in ambient air based on active sampling combined with gas chromatography - mass spectrometry (GC-MS) was developed. The retention efficiency of five sampling sorbents (activated coconut charcoal, Carbopack B, Cromosorb 102, Cromosorb 106 and Isolute ENV+) was evaluated and Isolute ENV+ was found to be the most effective. A volume of 2700 L of air can be sampled without significant losses of the most volatile methylsiloxanes. To improve the sensitivity of the GC-MS method, concurrent solvent recondensation - large volume injection (CSR-LVI), using volumes up to 30 µl of sample extract, is proposed and limits of quantification down to 0.03-0.45 ng m(-3), good linearity (r>0.999) and precision (RSD %<9%) were obtained. The developed method was applied to the analysis of ambient air. Concentrations of linear and cyclic methylsiloxanes in indoor air ranging from 3.9 to 319 ng m(-3) and between 48 and 292668 ng m(-3), were obtained, respectively, while levels from 6 to 22 ng m(-3) for linear and between 2.2 and 439 ng m(-3) for cyclic methylsiloxanes in outdoor air from Barcelona (Spain), were found.

Determination of polycyclic and nitro musks in environmental water samples by means of microextraction by packed sorbents coupled to large volume injection-gas chromatography–mass spectrometry analysis

In this work the development and validation of a new procedure for the simultaneous determination of 9 nitro and polycyclic musk compounds: musk ambrette (MA), musk ketone (MK), musk mosken (MM), celestolide (ADBI), phantolide (AHMI), tonalide (AHTN), traseolide (ATII), cashmeran (DPMI) and galaxolide (HHCB) in environmental water samples (estuarine and wastewater) using microextraction by packed sorbent (MEPS) followed by large volume injection-gas chromatography–mass spectrometry (LVI-GC–MS) was carried out. Apart from the optimization of the different variables affecting MEPS (i.e., nature of the sorbent, nature of the solvent elution, sample load, and elution/injection volume) extraction recovery was also evaluated, not only for water samples but also for environmental water matrices such as estuarine and waste water. The use of two deuterated analogs ([2H3]-AHTN and [2H15]-MX) was successfully evaluated in order to correct matrix effect in complex environmental matrices such as influent samples from wastewater treatment plants. Method detection limits (MDLs) ranged from 5 to 25ngL−1, 7 to 39ngL−1 and 8 to 84ngL−1 for influent, effluent and estuarine samples, respectively. Apparent recoveries were higher than 75% for all target compounds in all the matrices studied (estuarine water and wastewater) and the precision of the method, calculated as relative standard deviation (RSD), was below 13.2% at 200ngL−1 concentration level and below 14.9% at low level (20ngL−1 for all the target analytes, except for AHTN which was set at 40ngL−1 and HHCB at 90ngL−1, due to the higher MDL values presented by those target compounds). Finally, this MEPS procedure was applied to the determination of the target analytes in water samples, including estuarine and wastewater, from two estuaries, Urdaibai (Spain) and Adour (France) and an established stir-bar sorptive extraction-liquid desorption/large volume injection-gas chromatography–mass spectrometry (SBSE-LD/LVI-GC–MS) method was performed in parallel for comparison. Results were in good agreement for all the analytes determined, except for DPMI.

Fully automated determination of macrocyclic musk fragrances in wastewater by microextraction by packed sorbents and large volume injection gas chromatography–mass spectrometry

A fully automated method has been developed for the determination of eight macrocyclic musk fragrances in urban wastewater. The procedure includes the enrichment of the analytes by microextraction by packed sorbent (MEPS) followed by large volume injection–gas chromatography–mass spectrometry (LVI–GC–MS). The main factors in the MEPS technique were optimized. For all of the analytes, the highest enrichment factors were achieved when 4mL samples were extracted by using C18 MEPS-sorbent and 50μL of ethyl acetate were used for desorption. The eluate was directly analysed by GC–MS. Detection limits were found to be between 5ngL−1 and 10ngL−1, depending on the target analytes. In addition, under optimized conditions, the method gave good levels of intra-day and inter-day repeatability in wastewater samples with relative standard deviation (RSD) (n=3, 1000ngL−1) less than 5% and 9%, respectively. The applicability of the method was tested with wastewater samples from two influent and effluent urban wastewater treatment plants (WWTPs). The analysis of influent urban wastewater revealed the presence of most of the macrocylic musks at concentrations higher than the method quantification limits (MQLs), being the most abundant analyte ambrettolide at 9.29μgL−1. In addition, the analyses of effluent urban wastewater showed a decrease in the concentrations with macrocyclic musk concentrations of between not detected (n.d.) and 2.26μgL−1 being detected.

Comparison of the selectivity of different sorbent phases for bar adsorptive microextraction—Application to trace level analysis of fungicides in real matrices

Bar adsorptive micro-extraction combined with liquid desorption followed by large volume injection–gas chromatography–mass spectrometry operating in the selected-ion monitoring acquisition mode (BAμE–LD/LVI–GC–MS(SIM)) was developed for the determination of trace levels of ten fungicides (azoxystrobin, difenoconazole, metalaxyl-M, myclobutanil, penconazole, tebuconazole, flusilazole, cyprodinil, procymidone and benalaxyl) in aqueous matrices. By comparing different sorbent coatings (two activated carbons, two styrene–divinylbenzene and one modified pyrrolidone polymers) through BAμE, the latter phase showed much higher selectivity and capacity offering multiple mechanisms of interaction, even against polydimethylsiloxane by stir bar sorptive extraction. Assays performed on 25mL of water samples spiked at the 0.8μg/L level, yielded recoveries ranging from 100.0 to 107.8%, under optimized experimental conditions; BAμE(modified pyrrolidone) – equilibrium time: 4h (1000rpm), pH 5.5; LD – solvent:methanol/acetonitrile (1/1), 15min with sonification. The analytical performance showed convenient detection limits (4.0–30.0ng/L) and excellent linear dynamic ranges (0.04–1.60μg/L) with remarkable correlation coefficients (r2>0.9980). Excellent repeatability was also achieved through intraday (RSD<13.7%) and interday (RSD<9.9%) assays. By using the standard addition methodology, the application of the present analytical approach on tap and ground water, as well as, wine samples revealed good sensitivity and absence of matrix effects. The proposed method operating under floating sampling technology proved to be a suitable sorption-based static microextraction alternative to monitor fungicides in real matrices, showing to be easy to implement, reliable, sensitive, requiring low sample volume and the possibility to choose the most selective sorbent coating according to the targets of interest.

Determination of polycyclic aromatic hydrocarbons in water samples using online microextraction by packed sorbent coupled with gas chromatography–mass spectrometry

A fully automated microextraction by packed sorbents (MEPS) coupled with large volume injection gas chromatography–mass spectrometry (GC–MS) has been developed for the determination of eight polycyclic aromatic hydrocarbons (PAHs) in environmental water samples. Naphthalene (Nap), pyrene (Pyr), anthracene, acenaphthylene, phenanthrene, fluoranthene (Flr), fluorene and acenaphthene were the PAHs studied. The performance of the microextraction-GC–MS protocol was compared with solid phase extraction (SPE) and GC–MS analysis. Under optimized experimental conditions, the methods were linear for all analytes in the following ranges: 0.05–2.0μgL−1 (MEPS) and 0.25–10.0μgL−1 (SPE). The correlation coefficients (R2) were in the range 0.9965–0.9997 (MEPS) and 0.9978–0.9998 (SPE) for all the analytes. Limits of detection (LODs) for 2mL samples (MEPS) ranged from 0.8ngL−1 to 8.2ngL−1. LODs for 50mL samples (SPE) were between 4.8ngL−1 and 35.9ngL−1. The two methods were successfully applied to the determination of the 8 PAHs in environmental waters, with recoveries in the range of 70–117% (MEPS) and 72–134% (SPE) for a real spiked sample. The two sample preparation processes showed good repeatabilities with intra-day relative standard deviations below 14.0% (MEPS) and 14.6% (SPE). Nap, Flr and Pyr were found in a river water sample.

Membrane-assisted solvent extraction coupled to large volume injection–gas chromatography–mass spectrometry for the determination of a variety of endocrine disrupting compounds in environmental water samples

Membrane-assisted solvent extraction coupled to large volume injection in a programmable temperature vaporisation injector using gas chromatography–mass spectrometry analysis was optimised for the simultaneous determination of a variety of endocrine disrupting compounds in environmental water samples (estuarine, river and wastewater). Among the analytes studied, certain hormones, alkylphenols and bisphenol A were included. The nature of membranes, extraction solvent, extraction temperature, solvent volume, extraction time, ionic strength and methanol addition were evaluated during the optimisation of the extraction. Matrix effects during the extraction step were studied in different environmental water samples: estuarine water, river water and wastewater (influent and effluent). Strong matrix effects were observed for most of the compounds in influent and effluent samples. Different approaches were studied in order to correct or minimise matrix effects, which included the use of deuterated analogues, matrix-matched calibration, standard addition calibration, dilution of the sample and clean-up of the extract using solid-phase extraction (SPE). The use of deuterated analogues corrected satisfactorily matrix effect for estuarine and effluent samples for most of the compounds. However, in the case of influent samples, standard addition calibration and dilution of the sample were the best approaches. The SPE clean-up provided similar recoveries to those obtained after correction with the corresponding deuterated analogue but better chromatographic signal was obtained in the case of effluent samples. Method detection limits in the 5-54 ng L(-1) range and precision, calculated as relative standard deviation, in the 2-25% range were obtained.

Membrane assisted solvent extraction coupled to large volume injection-gas chromatography–mass spectrometry for trace analysis of synthetic musks in environmental water samples

This work describes the optimisation, validation and application of membrane assisted solvent extraction (MASE) together with a large volume injection (LVI) in a programmable temperature vaporisation (PTV) injector coupled to gas chromatography–mass spectrometry (GC–MS) for the quantification of ten synthetic musk fragrances (musks) in surface and wastewater samples. Regarding the MASE, musks were extracted from 150mL of aqueous samples to 200μL of n-hexane hold in home-made low density polyethylene (LDPE) bags. The extraction took 240min and the performance of the method made possible the direct analysis of the extracts by LVI-PTV-GC–MS without needing any further treatment and avoiding losses of analytes. During the optimisation of LVI-PTV set-up, the response surfaces of every analyte signal against the cryo-focussing temperature, injection speed and vent time were built. Finally, the figures of merit of the whole procedure allowed the analysis of most of the musks owing to the low method detection limits (between 4 and 25ngL−1) and good precisions (<20%). In fact, this method was successfully applied to the analysis of musks in surface and wastewater samples. Galaxolide and tonalide are the main two synthetic musks observed in most of the analysed environmental water samples.

Fully automated determination of parabens, triclosan and methyl triclosan in wastewater by microextraction by packed sorbents and gas chromatography–mass spectrometry

A fully automated method for the determination of triclosan (TCS), its derivative methyl triclosan (MeTCS) and six parabens (esters of 4-hydroxybenzoic acid) including branched and linear isomers of propyl ( i-PrP and n-PrP) and butyl paraben ( i-BuP and n-BuP) in sewage water samples is presented. The procedure includes analytes enrichment by microextraction by packed sorbent (MEPS) coupled at-line to large volume injection-gas chromatography–mass spectrometry (LVI-GC–MS). Under optimised conditions, compounds were extracted from 2 mL samples, adjusted at pH 3, using a C18 MEPS-sorbent. Adsorbed analytes were eluted directly into the Programmable Temperature Vaporizer (PTV) injector of the chromatograph with 2 × 25 μL of ethyl acetate. They were quantified using standard solutions in ultrapure water submitted to the same sample enrichment process as real sewage water samples. After signal normalisation using isotopic labelled species as internal surrogates, no differences were noticed among the extraction efficiency for sewage and ultrapure water; moreover, the proposed method reported lineal calibration curves from 0.1 to 10 ng mL −1, relative standard deviations (%RSD) between 2 and 7.1% and limits of detection (LODs) varying from 0.001 to 0.015 ng mL −1 in ultrapure water and from 0.02 to 0.59 ng mL −1 in the most complex sample (raw wastewater).