Automated Solid-phase Microextraction Research Articles

Determining Marine Biodegradation Kinetics of Chemicals Discharged from Offshore Oil Platforms─Whole Mixture Testing at High Dilutions Increases Environmental Relevance.

Offshore oil platforms discharge enormous volumes of produced water that contain mixtures of petrochemicals and production chemicals. It is crucial to avoid the discharge of particularly those chemicals that are persistent in the marine environment. This study aims to (1) develop a biodegradation testing approach for discharged chemicals by native marine microorganism, (2) determine how dilution affects biodegradation, and (3) determine biodegradation kinetics for many discharged chemicals at low and noninhibitory concentrations. Produced water from an offshore oil platform was diluted in the ratio of 1:20, 1:60, and 1:200 in seawater from the same location and incubated for 60 days at 10 °C. Automated solid-phase microextraction GC-MS was used as a sensitive analytical technique, and chemical-specific primary degradation was determined based on peak area ratios between biotic test systems and abiotic controls. Biodegradation was inhibited at lower dilutions, consistent with ecotoxicity tests. Biodegradation kinetics were determined at the highest dilution for 139 chemicals (43 tentatively identified), and 6 chemicals were found persistent (half-life >60 days). Nontargeted analysis by liquid chromatography-high-resolution MS was demonstrated as a proof-of-principle for a comprehensive assessment. Biodegradation testing of chemicals in discharges provides the possibility to assess hundreds of chemicals at once and find the persistent ones.

Flow-modulation comprehensive two-dimensional enantio-gas chromatography: A valid and flexible alternative to heart-cutting multidimensional enantio-gas chromatography

The present research is focused on the proposal of use of flow-modulation comprehensive two-dimensional enantio-gas chromatography (FM eGC × GC) as a valid, flexible, and possibly superior alternative to heart-cutting multidimensional enantio-GC (eMDGC). The latter, a technique of demonstrated utility, is used specifically for the targeted separation of chiral compounds, whereas FM eGC × GC can produce both targeted and high-resolution untargeted information in a single run. It is clearly possible to use eMDGC for untargeted analysis, often with a flame ionization detector (stand-by analysis), to monitor a first-dimension (1D) separation, of much lower peak capacity compared to FM eGC × GC. If eMDGC is used with mass spectrometry (MS), it is normally exploited to monitor the second-dimension (2D) separation.The analytical instrument consisted of automated solid-phase microextraction (SPME), and a low duty-cycle FM eGC × GC system (with time-of-flight MS), equipped with an enantioselective 1D column (2,3-di-O-methyl-6-t-butyl silyl β-cyclodextrin derivative) and a 2D polyethylene glycol one. Ten Marsala wines were subjected to analysis, for the determination of chiral lactones (many at the low ppb level, due to the high concentration capacity of SPME) and for general analyte profiling. In many instances, highly complex chromatograms were attained, with statistical analysis (ANOVA-simultaneous component analysis and partial least squares discriminant analysis) used for sample differentiation.

High-Throughput and Rapid Screening of Drugs of Abuse in Saliva by Multi-Segment Injection Using Solid-Phase Microextraction-Automated Microfluidic Open Interface-Mass Spectrometry.

There is great demand for analytical methods capable of providing high-throughput and rapid screening, especially for anti-doping and clinical point-of-care applications. In this work, automated microfluidic open interface-mass spectrometry (MOI-MS) was used for coupling with high-throughput, automated solid-phase microextraction (SPME) to achieve this objective. The design of the MOI-MS interface provides a continuous and stable electrospray fluid flow to the MS without introducing any bubble, a feature that we exploit to introduce the concept of multi-segment injection for the determination of multiple samples in a single MS run. By eliminating the need to start a new MS run between sample assays, the developed approach provides significantly simplified protocols controlled by programmed software and increased reproducibility. Furthermore, the biocompatible SPME device, which utilizes coating consisting of hydrophilic-lipophilic balanced particles embedded in a polyacrylonitrile (PAN) binder, can be directly used for biological sample analysis, as the PAN acts as both a binder and a matrix-compatible barrier, thus enabling the enrichment of small molecules while eliminating interferences associated with the presence of interfering macromolecules. The above design was employed to develop a fast, quantitative method capable of analyzing drugs of abuse in saliva samples in as little as 75 s per sample. The findings indicate that the developed method provides good analytical performance, with limits of detection ranging between 0.05 and 5 ng/mL for analysis of 16 drugs of abuse, good calibration linear correlation coefficients (R2 ≥ 0.9957), accuracy between 81 and 120%, and excellent precision (RSD% < 13%). Finally, a proof-of-concept experiment was performed to demonstrate the method's suitability for real-time analysis in anti-doping applications.

Automated Solid-Phase Microextraction and Negative Chemical Ionization GC-MS for the Measurement of Synthetic Pyrethroids.

Synthetic pyrethroids are frequently detected as trace contaminants in sediment and natural waters. Because of the importance of measuring both total and freely available concentrations for ecotoxicity evaluations, solid-phase microextraction (SPME) combined with gas chromatography-mass spectrometry using negative chemical ionization (NCI-GC-MS) was investigated as an analytical technique. Automated SPME-NCI-GC-MS quantification of freely dissolved (and thus potentially bioavailable) pyrethroids in aqueous samples containing dissolved organic matter (DOM) was successfully applied. The introduction of stable isotope-labeled pyrethroid calibration standards into the water sample allows for the simultaneous determination of total concentrations. Because pyrethroids adsorb rapidly to container walls (especially in calibration standard solutions without DOM) it was necessary to develop a technique to minimize the resulting time-dependent losses from calibration standard solutions in autosampler vials as they await analysis. A staggered preparation of these analytical calibration standards immediately prior to analysis was shown to ameliorate this problem. The developed method provides accurate and reproducible results for aqueous samples containing a range of dissolved organic matter concentrations (e.g., sediment pore water or sediment/water mixtures) and yields practical benefits in comparison to conventional analysis methods, such as reduced sample volume requirements, reduced solvent consumption, and fewer sample manipulations, and makes simultaneous measurements of freely dissolved/bioavailable pyrethroids and total pyrethroids possible.

Biodegradation of an essential oil UVCB - Whole substance testing and constituent specific analytics yield biodegradation kinetics of mixture constituents

Testing and assessing the persistency, bioaccumulative and toxic properties of UVCBs (substances of Unknown or Variable composition, Complex reaction products or Biological materials) pose major technical and analytical challenges. The main aim of this study was to combine whole substance biodegradation testing with constituent specific analytics for determining primary biodegradation kinetics of the main UVCB constituents. An additional aim was to link the primary biodegradation kinetics of the main constituents to the bioaccumulation potential and baseline toxicity potential of the UVCB. Two closed biodegradation experiments were conducted using similar test systems but different analyses. The model substance, cedarwood Virginia oil, was tested at a low concentration and wastewater treatment plant effluent served as inoculum. We used microvolume solvent spiking for a quantitative mass transfer of the UVCB, while avoiding that co-solvent degradation would lead to anaerobic conditions. The biodegradation of UVCB constituents was determined with automated solid-phase microextraction coupled to GC-MS/MS using targeted analysis for main constituents and non-targeted analysis for minor constituents and non-polar degradation products. Primary biodegradation kinetics of main constituents, accounting for 73% w/w of the mixture, were successfully determined with degradation rate constants ranging from 0.09 to 0.25 d−1. Minor constituents were also degraded and non-polar degradation products were not observed. Finally, the bioaccumulation potential and baseline toxicity potential of the mixture at test start were calculated and both parameters decreased then substantially. The strength of the new approach is the possibility of biodegradation testing of a whole UVCB at low concentration while generating constituent specific biodegradation kinetics.

Analysis of furan in various instant noodles by solid-phase microextraction–gas chromatography/mass spectrometry

In this study, 158 samples of instant noodles were analysed according to the sauce (soup, black soybean sauce, spicy sauce), packaging (bag, bowl) and recipe (original, modified) for furan quantification by automated solid-phase microextraction–gas chromatography/mass spectrometry. The concentration range of furan in raw and cooked noodles was 4.24–13.2 and 1.71–8.14 ng/g, respectively. Among the sauces, black soybean sauce has the highest furan levels of 27.0–218 (raw) and 8.47–126 (cooked) ng/g. After cooking, the furan content decreased by 37.7% (noodles), 86.2% (soup base), 89.1% (black soybean sauce) and 82.8% (spicy sauce). The reduction rate of furan in the sauce was more than two-fold higher than that in noodles. The results obtained in this study are considered useful as a database for analysis of furan in instant noodles.

Optimization and validation of automated solid-phase microextraction arrow technique for determination of phosphorus flame retardants in water.

In the present work, a very sensitive and fully automated direct immersion PAL SPME Arrow procedure, coupled with GC-MS, has been developed and validated for determination of nine phosphorus flame retardants in different types of water samples (river, drinking and rainwater). PDMS/DVB was selected among three commercially available SPME Arrows (PDMS/DVB, DVB/PDMS/CWR and PDMS/CWR), since it resulted in the best sensitivity. The important experimental parameters were optimized via a central composite design response surface methodology and as result, extraction time of 65min, extraction temperature of 80 °C and added salt concentration of 19% (w/v), were selected as the optimum values. The optimized method showed linear response over the calibration range (2 - 500ng L-1), with R2-values higher than 0.9937. The precision (RSD%) measured by replicate analyses (n=7) was estimated at 2 and 100ng L-1 and was less than 29% and 21%, respectively. The LOQ of PAL SPME Arrow, calculated as S/N=10, was between 0.2 and 1.2ng L-1 (for triphenyl phosphate and tris-(1‑chloro‑2-propyl) phosphate, respectively) with extraction efficiencies between 5.9 and 31% (for tris-(1,3-dichloro-2-propyl) phosphate and tri-n‑butyl phosphate, respectively). To assess the performance of the developed technique for real samples, two river water samples, tap water from two regions and a rainwater sample were analyzed. Most of the target analytes were observed in the river samples with concentrations of 1.0 - 250ng L-1 and the obtained recoveries at 50ng L-1 ranged between 60 and 107%. Considering the figures of merit of the optimized method, PAL SPME Arrow-GC-MS showed to be the most sensitive analytical approach for determination of phosphorus flame retardants in water, with satisfying precision and accuracy, compared with conventional SPME-NPD, LLE-GC-MS and SPE-LC-MS/MS.

Odor-active volatile compounds profile of triploid rainbow trout with different marketable sizes

The present study identified the volatile compounds profile in raw muscle of triploid rainbow trout with different marketable sizes (eviscerated weight: 2 kg, 3 kg and 4 kg, respectively). Six fish per each size treatment were sampled in a local commercial trout farm, then raw muscles of sampled fish were filleted to detect the volatile compounds by using the gas chromatography-mass spectrometry (GCMS) analysis coupled with automated solid-phase microextraction (SPME) system. Results showed that a total of 58 volatile compounds were identified in raw muscle of triploid rainbow trout, including aldehydes (20 species), ketones (6 species), alcohols (9 species), hydrocarbons (11 species), aromatics (6 species) and miscellaneous compounds groups (6 species). The subtotal estimated concentration of aldehydes group was significantly higher than those of the other volatile groups (P < 0.05). Based on the odor activity value (OAV ≥ 1), 21 odor-active compounds may contribute to the overall odor, including pentanal, hexanal, (Z)-4-heptenal, heptanal, (E)-2-heptenal, octanal, (E,E)-2,4-heptadienal, (E)-2-octenal, nonanal, (E,Z)-2,6-nonadienal, (E)-2-nonenal, decanal, (E,E)-2,4-nonadienal, (E)-2-decenal, undecanal, 2,3-pentanedione, 2,3-octanedione, 1-heptanol, 1-octen-3-ol, 2-ethyl-furan and 2-pentyl-funan. The marketable fish of 2 kg had the most numerous volatiles species and the highest total estimated concentration. The profile of 58 identified volatile compounds in 2 kg fish was different with it in 3 kg and 4 kg fish. However, there was no difference in the total odor activity value of all odor-active compounds among three size treatments (P > 0.05). Based on the principle component analysis and cluster analysis using the odor activity values of 21 odor-active compounds, the overall odors of raw muscle might be similar in triploid rainbow trout with different marketable sizes.

Aromatic profile changes of Thai mangoes during heat processing

In Thailand, mango is economically one of the most important fruits. Mango flesh has a very short shelf life and is therefore subjected to processing such as juicing and drying. Thermal processing leads to physiochemical or phytochemical changes including in fruit aromatic profiles. The research aim of this study was to investigate the effect of heat on free volatile aromas of mango fruits and to identify descriptive profiles from the ripe pulp of four Thai cultivars viz. ‘Sam-pee’, ‘Chok-Anan’, ‘Mahachanok’ and ‘Kaew’. Ripe mango flesh was analyzed for free volatile aroma by automated Solid-phase Microextraction (SPME) before and after heating at 85°C for 15 min. The SPME results showed that Thai mango flesh before and after heat treatment comprised typical aromatic compounds of pine (i.e., α-pinene, β-pinene, terpinolene cis-β-ocimene), herbs (i.e., β-phellandrene, phellandrene, eucalyptus), flowers (i.e., sabinene, β-myrcene, para cymene, trans-β-ocimene) and citrus fruit (i.e., D-3-carene, α-terpinene, limonene, ϒ-terpinene). Heating altered these major aromatic compositions in all four Thai cultivars. Similar alteration patterns were also observed by sensory evaluations. The results of this research will be utilized to standardise mango processing and to benefit future food-product development.

Mixture Effects on Biodegradation Kinetics of Hydrocarbons in Surface Water: Increasing Concentrations Inhibited Degradation whereas Multiple Substrates Did Not.

Most biodegradation tests are conducted using single chemicals at high concentrations, although these chemicals are present in the environment as mixtures at low concentrations. A partitioning-based platform was recently developed for biodegradation testing of composed mixtures of hydrophobic chemicals at ng/L to μg/L concentrations. We used this platform to study the concentration and mixture effect on biodegradation kinetics. Biodegradation tests were conducted in 20 mL vials using environmental water samples as inocula. Passive dosing was applied (1) to vary initial test concentrations of individual test compounds and (2) to vary the number of mixture components between 1 and 16. Automated solid-phase microextraction coupled to gas chromatography-mass spectrometry was used to measure substrate depletion relative to abiotic controls. The number of mixture components had no or only a limited effect on the biodegradation half times for three compounds when tested at environmentally relevant concentrations. In contrast, longer lag phases and half lives were observed for single compounds when tested at higher concentrations that approached aqueous solubility. The obtained results support that simultaneous testing of multiple chemicals at low concentrations can accelerate the generation of biodegradation kinetic data, which are more environmentally relevant compared with data from tests conducted with single chemicals at much higher concentrations.

Validation of analytical method for furan determination in eight food matrices and its levels in various foods.

In this study, an automated solid-phase microextraction coupled with gas chromatography and mass spectrometry method was developed and validated for the determination of furan in eight matrices including ham, milk, apple juice, rice porridge, peanut butter, flatfish, tuna (canned) and seaweed. The calibration curves were highly linear (r2 >0.990) and the limit of detection and limit of quantification ranged from 0.01-0.02 and 0.04-0.06ng/g, respectively. The recovery ranged from 77.81-111.47%. The validated method was used to analyse the furan levels in 120 foods. The highest levels of furan were detected in black tea (172.05ng/g) and red ginseng extract (89.27ng/g). Whelk (canned) contained a high furan content (21.34ng/g) among the seafood samples.

High-Throughput Analysis of Selected Urinary Hydroxy Polycyclic Aromatic Hydrocarbons by an Innovative Automated Solid-Phase Microextraction.

High-throughput screening of samples is the strategy of choice to detect occupational exposure biomarkers, yet it requires a user-friendly apparatus that gives relatively prompt results while ensuring high degrees of selectivity, precision, accuracy and automation, particularly in the preparation process. Miniaturization has attracted much attention in analytical chemistry and has driven solvent and sample savings as easier automation, the latter thanks to the introduction on the market of the three axis autosampler. In light of the above, this contribution describes a novel user-friendly solid-phase microextraction (SPME) off- and on-line platform coupled with gas chromatography and triple quadrupole-mass spectrometry to determine urinary metabolites of polycyclic aromatic hydrocarbons 1- and 2-hydroxy-naphthalene, 9-hydroxy-phenanthrene, 1-hydroxy-pyrene, 3- and 9-hydroxy-benzoantracene, and 3-hydroxy-benzo[a]pyrene. In this new procedure, chromatography’s sensitivity is combined with the user-friendliness of N-tert-butyldimethylsilyl-N-methyltrifluoroacetamide on-fiber SPME derivatization using direct immersion sampling; moreover, specific isotope-labelled internal standards provide quantitative accuracy. The detection limits for the seven OH-PAHs ranged from 0.25 to 4.52 ng/L. Intra-(from 2.5 to 3.0%) and inter-session (from 2.4 to 3.9%) repeatability was also evaluated. This method serves to identify suitable risk-control strategies for occupational hygiene conservation programs.

The capillary gap sampler, a new microfluidic platform for direct coupling of automated solid-phase microextraction with ESI-MS.

A new technology for rapid, automated coupling of solid-phase microextraction and mass spectrometry is introduced. Use of a so-called capillary gap sampler for automated solid-phase microextraction and direct delivery of the extracted analytes to a mass spectrometer provides certain advantages over existing technologies: coupling of the capillary gap sampler to a mass spectrometer offers quick, automated, and site-specific extraction from very low volume samples. High stability, reusability, and repeatability were achieved through systematic optimization. Diazepam, oxazepam, and nordiazepam were used as test compounds in all experiments. The ability of the sampler to extract benzodiazepines from human plasma (limit of detection 0.3 μg/mL) in the therapeutic range was confirmed. A linear dynamic range from 1 to 1000 ng/mL for all three analytes was found. The relative standard deviation of 20 extractions was between 11% and 17%, for oxazepam, nordiazepam, and diazepam, indicating acceptable repeatability of the method. Graphical Abstract Schematic of the desorption step inside the liquid bridge formed between two capillaries in thecapillary gap sampler.

Can solid-phase microextraction replace solvent extraction for water analysis in fish bioconcentration studies with highly hydrophobic organic chemicals?

With the aim to refine water analysis in fish bioconcentration studies, automated solid-phase microextraction (SPME) was used as an alternative approach to conventional solvent extraction (liquid-liquid extraction [LLE]) for the extraction of 3 hydrophobic organic chemicals (HOCs; log KOW 5.5-7.8) from flow-through studies with rainbow trout (Oncorhynchus mykiss). The results showed that total concentrations extracted by SPME combined with internal standards and LLE are equal. The results further verify the possibility of simultaneous extraction of total and freely dissolved HOC concentrations by SPME. Freely dissolved concentrations allow the assessment of sorption and bioavailability of HOCs in bioconcentration studies and their potential impact on resulting bioconcentration factors (BCFs). Reduction in freely dissolved water concentrations can result in an underestimation of BCFs if they are calculated based on total water concentrations. For polychlorinated biphenyl (PCB) 153, a significant increase in BCF value was observed when freely dissolved concentrations were taken into account. However, log BCF values calculated based on freely dissolved concentrations did not correlate linearly with log KOW values above 5 to 6. This pointed to further influences besides a reduction in freely dissolved water concentrations by sorption to organic matter. The results can aid in assessment of the factors that influence bioconcentration systems and also give important information regarding the possible replacement of LLE by SPME for water analysis of highly HOCs in fish bioconcentration studies. Environ Toxicol Chem 2017;36:2887-2894. © 2017 The Authors. Environmental Toxicology and Chemistry Published by Wiley Periodicals, Inc. on behalf of SETAC.

Inter-laboratory validation of automated SPME-GC/MS for determination of pesticides in surface and ground water samples: sensitive and green alternative to liquid–liquid extraction

An automated solid-phase microextraction gas chromatography/mass spectometry (SPME-GC/MS) method was developed for the determination of semi-volatile pesticides from several classes with a wide range of polarities in an environmental matrix, and validated according to the rigorous standards of a large commercial laboratory reporting data requiring regulatory acceptance with the purpose of being used as a standard test protocol. The target analytes showed a detection limit of 0.05–1 μg L−1, good calibration linearity (R2 &amp;gt; 0.99) with a wide linear range of 0.05–20 μg L−1, and accuracy in the range of 80–110 at three levels of calibration with relative standard deviation below 7% by commercial polydimethylsiloxane/divinylbenzene (PDMS/DVB) SPME fiber. An extensive study between SPME and liquid–liquid extraction as a reference US EPA method was performed from several analytical aspects including sensitivity, accuracy, repeatability, and greenness. The SPME method was validated through split blind analyses of 16 fortified surface and ground water samples within 4 months at Maxxam Analytics, the reference laboratory, and the University of Waterloo. Both methods were shown to be very accurate, with the highest frequency of results falling in the 70–130% accuracy range. The SPME method was shown to be more sensitive than the LLE, while requiring a lower volume of sample.

Investigation of the kinetic process of solid phase microextraction in complex sample

The presence of complex matrix in the aquatic system affects the environmental behavior of hydrophobic organic compounds (HOCs). In the current study, an automated solid-phase microextraction (SPME) desorption method was employed to study the effect of 2-hydroxypropyl-β-cyclodextrin (β-HPCD) on the kinetic process of 5 selected polyaromatic hydrocarbons (PAHs) desorbing from the fiber in aqueous sample. The results showed that the added β-HPCD facilitated the desorption rates of PAHs from SPME fiber coating, and the enhancement effect can be predicted by a proposed theoretical model. Based on this model, the kinetic parameters of organic compounds desorbing from the SPME fiber can be determined, and the calculated results showed good agreement with the experimental data. In addition, the effect of temperature on the desorption kinetic was investigated. The results found that the SPME desorption time constant increased as the sampling temperature elevated, and followed the Arrhenius equation. Also, the temperature facilitated the desorption of HOCs from the bound matrix so that increased the lability degrees of the bound compounds. Finally, a calibration method based on the proposed theoretical model was developed and applied for the analysis of unknown sample.

Flow-assisted automated solid-phase microextraction for the determination of chloroethers in aqueous matrices

In this study a method of flow-assisted automated solid-phase microextraction (FA-SPME) was developed for the determination of organic pollutants in aqueous samples. A CTC Combi-PAL autosampler coupled with gas chromatography–mass spectrometry (GC–MS) was used to automate the entire extraction process. In this method, the SPME fibre was exposed to 100 mL of sample in a direct immersion mode for 10 min. After exposure, the fibre was desorbed at the injection port of GC–MS. To demonstrate the applicability of FA-SPME, chloroethers were selected as model compounds. Good linear correlation was found over a concentration range of 0.5–100 µg/L. The detection limits of the method were determined between 0.02 and 0.05 µg/L with the coefficients of determination (R2) from 0.9980 to 0.9996. The relative standard deviations (RSDs) of the FA-SPME for three sequential FA-SPME analyses were determined to be in the range between 1.2% and 6.2% (n = 3). The applicability of the method was assessed by means of recovery studies and satisfactory values for all compounds were obtained. This optimised method was used in the analysis of water and human urine samples to show the matrix effect on FA-SPME. This FA-SPME/GC–MS is substantially faster and suitable for the routine continuous flow-mode environmental monitoring applications.

An automated solid-phase microextraction method based on magnetic molecularly imprinted polymer as fiber coating for detection of trace estrogens in milk powder

A new automated solid-phase micro extraction (SPME) sampling method was developed for quantitative enrichment of estrogens (ES) from milk powder, using magnetic molecularly imprinted polymer (MMIP) as fiber coating. The method (MMIP-SPME) was built with several electromagnetic stainless steel fibers, placed in parallel for simultaneously extraction. The MMIP was synthesized using core–shell Fe3O4@SiO2 nanoparticles (NPs) as magnetic support. Estradiol (E2) was employed as the template molecule, acrylamide (AA) as functional monomer, and ethylene glycol dimethacrylate (EGDMA) as cross-linker. MMIP can be easily absorbed or desorbed from fibers when the current is turned on or off, creating magnetism. Compared to traditional MIP-SPME, the prepared procedure of MMIP-SPME is time-saving and organic solvent-free. The proposed device significantly improved the efficiency of separation and enrichment of estrogens from complex matrices thereby and facilitating the pretreatment steps by electromagnetically controlled extraction fibers to achieve full automation. Several experimental parameters were studied, including extraction and desorption kinetics, solution pH, desorption solution, ratio, and shuttle rate. The newly developed MMIP-SPME showed good sensitivity and high binding capacity, fast adsorption kinetics and desorption kinetics for estrone (E1), estradiol (E2), estriol (E3) and diethylstilbestrol (DES) under optimized conditions. The detection limits for the four estrogens were 1.5–5.5ngg−1 with excellent reproducibility (RSD values less than 7.1%) when milk powder samples spiked with analytes at 20, 100 and 250ngg−1 were studied.

Simultaneous determination of polycyclic aromatic hydrocarbons and their chlorination by-products in drinking water and the coatings of water pipes by automated solid-phase microextraction followed by gas chromatography–mass spectrometry

In this study, an automated method for the simultaneous determination of polycyclic aromatic hydrocarbons (PAHs) and their chlorination by-products in drinking water was developed based on online solid-phase microextraction-gas chromatography–mass spectrometry. The main focus was the optimisation of the solid-phase microextraction step. The influence of the agitation rate, type of fibre, desorption time, extraction time, extraction temperature, desorption temperature, and solvent addition was examined. The method was developed and validated using a mixture of 17 PAHs, 11 potential chlorination by-products (chlorinated and oxidised PAHs) and 6 deuterated standards. The limit of quantification was 10ng/L for all target compounds. The validated method was used to analyse drinking water samples from three different drinking water distribution networks and the presumably coal tar-based pipe coatings of two pipe sections. A number of PAHs were detected in all three networks although individual compositions varied. Several PAH chlorination by-products (anthraquinone, fluorenone, cyclopenta[d,e,f]phenanthrenone, 3-chlorofluoranthene, and 1-chloropyrene) were also found, their presence correlating closely with that of their respective parent compounds. Their concentrations were always below 100ng/L. In the coatings, all PAHs targeted were detected although concentrations varied between the two coatings (76–12,635mg/kg and 12–6295mg/kg, respectively). A number of chlorination by-products (anthraquinone, fluorenone, cyclopenta[d,e,f]phenanthrenone, 3-chlorofluoranthene, and 1-chloropyrene) were also detected (from 40 to 985mg/kg), suggesting that the reaction of PAHs with disinfectant agents takes place in the coatings and not in the water phase after migration.

Determination of steroids, caffeine and methylparaben in water using solid phase microextraction-comprehensive two dimensional gas chromatography–time of flight mass spectrometry

Analysis of several emerging contaminants (steroids, caffeine and methylparaben) in water using automated solid-phase microextraction with comprehensive two dimensional gas chromatography coupled to time of flight mass spectrometry (SPME-GCxGC–ToF/MS) is presented. Experimental design was used to determine the best SPME extraction conditions and the steroids were not derivatized prior to injection. SPME-GCxGC–ToF/MS provided linear ranges from 0.6 to 1200μgL−1 and limits of detection and quantitation from 0.02 to 100μgL−1. A series of river water samples obtained locally were subjected to analysis. SPME-GCxGC–ToF/MS is readily automated, straightforward and competitive with other methods for low level analysis of emerging contaminants