Fast and sensitive environmental analysis utilizing microextraction in packed syringe online with gas chromatography–mass spectrometry (original) (raw)
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Journal of Chromatography B, 2004
A new technique for sample preparation on-line with LC and GC-MS assays was developed. Microextraction in a packed syringe (MEPS) is a new miniaturised, solid-phase extraction technique that can be connected on-line to GC or LC without any modifications. In MEPS approximately 1 mg of the solid packing material is inserted into a syringe (100-250 l) as a plug. Sample preparation takes place on the packed bed. The bed can be coated to provide selective and suitable sampling conditions. The new method is very promising. It is very easy to use, fully automated, of low cost and rapid in comparison with previously used methods. This paper presents the development and validation of a method for microextraction in packed syringe MEPS on-line with GC-MS. Local anaesthetics in plasma samples were used as model substances. The method was validated and the standard curves were evaluated by the means of quadratic regression and weighted by inverse of the concentration: 1/x for the calibration range 5-2000 nM. The applied polymer could be used more than 100 times before the syringe was discarded. The extraction recovery was between 60 and 90%. The results showed close correlation coefficients (R > 0.99) for all analytes in the calibration range studied. The accuracy of MEPS-GC-MS was between 99 and 115% and the inter-day precision (n = 3 days), expressed as the relative standard deviation (R.S.D.%), was 3-10%.
TrAC Trends in Analytical Chemistry, 2002
Modern gas chromatography-mass spectrometry (GC-MS) methods and equipment, with the sensitivity and structural information these methods provide, make GC-MS an excellent choice for field detection and identification of a range of organic chemicals. Numerous sampling techniques allow detection of GC-MS analytes in environmental matrices, although multiple sample-handling steps and use of extraction solvents increase the complexity and time needed to complete analyses. Solidphase microextraction (SPME) has been shown to be suitable for sampling environmental contaminants from air, water and soil for GC-MS analysis. We provide applied examples of environmental samples collected and analyzed in the field using SPME-GC-MS for qualitative identification of workplace air contaminants from a poorly characterized paint and of gas-phase contaminants present during forensic and clean-up operations following a large fire involving aircraft fuel. In both instances, passive SPME sampling concentrated analytes from the air following short sampling periods and was followed immediately by GC-MS analysis in the field, without further sample preparation. The SPME sampling method is attractive for field use because of its portability, simplicity, broad applications, sensitivity, and favorable attributes as a sample-introduction method for GC-MS analyses. #
Microchemical Journal, 2020
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Biomedical Chromatography, 2012
In this study the use of micro-liquid chromatography coupled to tandem mass spectrometry (mLC-MS/MS) was investigated in routine bioanalysis application for separation and quantification of pro-drug AZD6319 (developed for aldezheimer treatment). Microextraction by packed sorbent (MEPS) was used as sample clean-up method. The focus of this study was put on the evaluation of the usability of smaller column diameters such as 1.0 and 0.3 mm instead of 2.1 mm in bioanalysis application to reduce solvent consumption and sample volumes. Solvent consumption was reduced by 80% when a 1.0 mm column was used compared with 2.1 mm column. Robustness of the micro-columns in terms of accuracy and precision was investigated. The application of mLC-MS/MS for the quantitative analysis of AZD6319 in plasma samples showed good selectivity, accuracy and precision. The coefficients of determination (R 2) were >0.998 for all runs using plasma samples on the studied micro-columns. The inter-day accuracy values for quality control samples ranged from 99 to 103% and from 96 to 105% for 0.3 Â 50 mm and 1.0 Â 50 mm columns, respectively. The inter-day precision values ranged from 4.0 to 9.0% and from 4.0 to 8.0% for 0.3 Â 50 and 1.0 Â 50 mm columns, respectively. In addition the sensitivity was increased by three times using a 1.0 mm column compared with 2.1 mm. Furthermore, robustness of the micro-columns from different manufacturers was investigated.
Analytical Chemistry, 2000
The determination of distribution coefficients is important for prediction of the chemical pathways of organic compounds in the environment. Solid-phase microextraction (SPME) is a convenient and effective method to measure the distribution of chemicals in a two-phase system. In the present study, the SPME distribution coefficient (K spme) of 16 priority aromatic hydrocarbons (PAHs) was determined with 100-µm poly(dimethylsiloxane) (PDMS) and 85-µm polyacrylate (PA) fibers. The partition coefficients and LeBas molar volumes were used to describe the linearity of the log K spme values of PAHs. Also, the validation of the distribution coefficient was examined using different sample volumes. The extraction time was dependent on the types of PAHs, and 20 min to 60 h was needed to reach equilibrium. The determined log K spme values ranged from 3.02 to 5.69 and from 3.37 to 5.62 for 100-µm PDMS and 85-µm PA fibers, respectively. Higher K spme values of low-ring PAHs were observed using 85-µm PA fiber. Good linear relationships between log K ow and log K spme for PAHs from naphthalene to benzo-[a]pyrene and from naphthalene to chrysene for 100-µm PDMS and 85-µm PA fibers, respectively, were obtained. The correlation coefficients were 0.969 and 0.967, respectively. The linear relationship between log K spme and the LeBas molar volume was only up to benz[a]anthracene for 85-µm PA fiber and up to chrysene for 100µm PDMS fiber. Moreover, the effect of sample volume can be predicted using the partition coefficient theory and excellent agreement was obtained between the experimental and theoretical absorbed amounts of low-ring PAHs. This result shows that the determined log K spme is more accurate than the previous method for estimating analytes with log K ow < 6 as well as for predicting the partitioning behaviors between SPME fiber and water. The physicochemical data of xenobiotic compounds are usually used to predict their environmental fate and effects and that of compounds with similar physicochemical properties. Hydorphobicity is one of the most important parameters governing the distribution behavior of xenobiotics in the environment. The octanol-water partition coefficient (K ow) is widely accepted as the
Journal of Chromatography A, 2009
An innovative and simple headspace solid-phase microextraction method using a novel diethoxydiphenylsilane fibre based on in situ derivatization with acetic anhydride was optimized and validated for the gas chromatography-mass spectrometry determination of some monohydroxy metabolites of polycyclic aromatic hydrocarbons, namely 1-hydroxynaphthalene, 2-hydroxynaphtalene, 9-hydroxyfluorene, 2-hydroxyfluorene and 1-hydroxypyrene at trace levels in human urine. Enzymatic hydrolysis was applied before derivatization, whereas extraction conditions, i.e. the effects of time and temperature of extraction and salt addition were investigated by experimental design. Regression models and desirability functions were applied to find the experimental conditions providing the highest global extraction response. These conditions were found in correspondence of an extraction temperature of 90 • C, an extraction time of 90 min and 25% NaCl added to urine samples. The capabilities of the developed method were proved obtaining limit of quantitations in the 0.1-2 g/l range, thus allowing the bio-monitoring of these compounds in human urine. A good precision was observed both in terms of intra-batch and inter-batch repeatability with RSD always lower than 14%. Recoveries ranging from 98(±3) to 121(±1)% and extraction yields higher than 72% were also obtained. Finally, the analysis of urine specimens of coke-oven workers revealed analytes' concentrations in the 2.2-164 g/l range, proving the exposure to PAHs of the involved workers.
For the first time, Vacuum Assisted Headspace Solid Phase Microextraction (Vac-HSSPME) is used for the recovery of polycyclic aromatic hydrocarbons (PAHs) from solid matrices. The procedure was investigated both theoretically and experimentally. According to the theory, reducing the total pressure increases the vapor flux of chemicals at the soil surface, and hence improves HSSPME extraction kinetics. Vac-HSSPME sampling could be further enhanced by adding water as a modifier and creating a slurry mixture. For these soil-water mixtures, reduced pressure conditions may increase the volatilization rates of compounds with a low K H present in the aqueous phase of the slurry mixture and result in a faster HSSPME extraction process. Nevertheless, analyte desorption from soil to water may become a rate-limiting step when significant depletion of the aqueous analyte concentration takes place during Vac-HSSPME. Sand samples spiked with PAHs were used as simple solid matrices and the effect of different experimental parameters was investigated (extraction temperature, modifiers and extraction time). Vac-HSSPME sampling of dry spiked sand samples provided the first experimental evidence of the positive combined effect of reduced pressure and temperature on HSSPME. Although adding 2 mL of water as a modifier improved Vac-HSSPME, humidity decreased the amount of naphthalene extracted at equilibrium as well as impaired extraction of all analytes at elevated sampling temperatures. Within short HSSPME sampling times and under mild sampling temperatures, Vac-HSSPME yielded linear calibration curves in the range of 1e400 ng g À1 and, with the exception of fluorene, regression coefficients were found higher than 0.99. The limits of detection for spiked sand samples ranged from 0.003 to 0.233 ng g À1 and repeatability from 4.3 to 10 %. Finally, the amount of PAHs extracted from spiked soil
Journal of Chromatography A, 2014
In this work, two different extraction procedures for the analysis of different polycyclic aromatic hydrocarbons (PAHs) in water by microextraction by packed sorbent (MEPS) have been compared in terms of sensitivity, reliability and time of analysis. The first method, called "draw-eject", consists of a sequence of cycles of aspirations and injections in the same vial; the second one, called "extract-discard", consists of a similar cycle sequence, but the aspired sample in this case is discarded into waste. The relevant partition equilibriums and extraction rates have been calculated by multivariate regression from the data obtained after MEPS gas chromatography-mass spectrometry (MEPS-GC-MS) analysis of 16 PAHs from water samples. Partitioning parameters for a priori prediction of solute sorption equilibrium, recoveries and preconcentration effects in aqueous and solvent systems have been calculated and compared for the two extraction procedures. Finally, real samples from sea, agricultural irrigation wells, streams and tap water were analyzed. Detection (S/N ≥ 3) and quantification (S/N ≥ 10) limits were calculated for the extraction processes. Under the experimental conditions used for the "draw-eject" procedure, these values were in the range 0.5-2 ng L −1 and 1.6-6.2 ng L −1 , while for the "extract-discard" procedure they ranged from 0.2 to 0.8 ng L −1 and from 0.8 to 2.0 ng L −1 , respectively.
Journal of Chromatography A, 2000
A solid-phase microextraction (SPME) procedure has been developed for the determination of 16 US Environmental Protection Agency promulgated polycyclic aromatic hydrocarbons (PAHs). Five kinds of SPME fibers were used and compared in this study. The extracted sample was analyzed by gas chromatography with flame ionization detection or mass spectrometry. Parameters affecting the sorption of analyte into the fibers, including sampling time, thickness of the fiber coating, and the effect of temperature, have been examined. Moreover, the feasibility of headspace SPME with different working temperatures was evaluated. The method was also applied to real samples. The 85-mm polyacrylate (PA) and 100-mm poly(dimethylsiloxane) (PDMS) fibers were shown to have the highest affinities for the selected PAHs. The PA fiber was more suitable than the PDMS fiber for the determination of low-ring PAHs while high sensitivity of high-ring PAHs was observed when a 100-mm PDMS fiber was used. The method showed good linearity between 0.1 and 100 ng / ml with regression coefficients ranging from 0.94 to 0.999. The reproducibility of the measurements between fibers was found to be very good. The precisions of PA and PDMS fibers were from 3 to 24% and from 3 to 14%, respectively. Headspace SPME is a valid alternative for the determination of two-to five-ring PAHs. A working temperature of 608C provides significant 26 enhancement in sensitivity of two-to five-ring PAHs having low vapor pressures (.10 mmHg at 258C) (1 mmHg5133.3 5 Pa) and low Henry's constants (.10 atm ml / mol) (1 atm51.01?10 Pa).
Journal of Chromatography A, 2010
An at-line analysis protocol is presented that allows the determination of four UV filters, two polycyclic musk compounds and caffeine in water at concentration level of ng L −1 . The fully automated method includes analytes enrichment by Microextraction by packed sorbent (MEPS) coupled directly to large volume injection-gas chromatography-mass spectrometry. Two common SPE phases, C8 and C18, were examined for their suitability to extract the target substances by MEPS. The analytes were extracted from small sample volumes of 800 L with recoveries ranging from 46 to 114% for the C8-sorbent and 65-109% for the C18-sorbent. Limits of detection between 34 and 96 ng L −1 enable the determination of the analytes at common environmental concentration levels. Both sorbents showed linear calibration curves for most of the analytes up to a concentration level of 20 ng mL −1 . Carryover was minimized by washing the sorbents 10 times with 100 L methanol. After this thorough cleaning, the MEPS are re-used and up to 70 analyses can be performed with the same sorbent. The fully automated microextraction GC-MS protocol was evaluated for the influence of matrix substances typical for wastewater. Dilution of samples prior to MEPS is recommended when the polar caffeine is present at high concentration. Real water samples were analyzed by the MEPS-GC-MS method and compared to standard SPE.