Automated Headspace Solid-phase Microextraction Research Articles

Automated Method for the Sensitive Analysis of Volatile Amines in Seawater.

Methylamines are polar, volatile, and organic nitrogen-containing compounds. They are challenging to analyze, limiting our understanding of their occurrence and role within the marine nitrogen cycle. We describe an automated headspace solid-phase microextraction method, coupled with gas chromatography and nitrogen phosphorus detection (HS-SPME-GC-NPD), for analyzing methylamines in seawater. Three SPME conditions were investigated: temperature, equilibration, and extraction. The method was 6-24 times more sensitive to trimethylamine (TMA) than to dimethylamine (DMA) and monomethylamine (MMA). DMA and TMA were detected in small seawater volumes (2.5-10 mL), at volumes 100-400 times that previously reported. Detection limits of 19.1, 6.6, and 4.1 nM (nMol L-1) for MMA, DMA, and TMA, respectively, were measured in 10 mL sample volumes. Sample throughput was 4-6 times greater than previously reported similar methods. According to the Blue Applicability Grade Index (BAGI) metric, the method was considered "practical" and scored 62.5. The method was used to measure methylamines in seawater samples collected from the Southern Ocean. DMA and TMA were detected at concentrations from < LoD-35 nM and < LoD-48 nM, respectively. This study offers a systematic and standardized method for MA analysis in seawater and can significantly advance understanding of their role in marine systems.

Automated headspace solid-phase microextraction-gas chromatography-mass spectrometry of trihalomethane and typical nitrogenous disinfection by-products in water

Disinfection by-products (DBPs) are detrimental to public health owing to their carcinogenicity and mutagenesis. Fast and reliable determination of DBPs is essential for ascertaining their formation, characteristics, and occurrence. This study reported an automated headspace solid-phase microextraction gas chromatography-mass spectrometry (HS-SPME-GC-MS) method for quantifying typical nitrogenous-DBPs, including haloacetonitriles (HANs), trichloronitromethane, and trihalomethanes (THMs). The analysis was further optimized by selecting SPME fiber coatings, extraction/desorption time and temperature, and salt addition. The optimized method examined the occurrence and stability of the selected DBPs in aqueous samples under different preservation conditions and showed good sensitivity (limit of detection: 0.010–0.320 µg/L) and precision. Most THMs and HANs with high recovery were preserved in ultrapure water under dark and low-temperature conditions. However, real samples exhibited greater analytical biases due to comprehensive effects of photochemistry, biochemistry, and physiochemistry. Based on the findings of this study, we recommend that tested samples should be preserved in a frozen state and analyzed within three days.

Eco-friendly Method for the Determination of Polycyclic Aromatic Hydrocarbons in Sediments by HS-SPME-GC/MS

This paper aimed to optimize a method for extraction of 26 polycyclic aromatic hydrocarbons (PAHs), which are petroleum markers, and their derivatives in surface sediment samples. The gas chromatography coupled to mass spectrometry detection with automated headspace solid phase microextraction (HS-SPME-GC/MS) was used in the studies. Extraction temperature, extraction time, stirring, sample mass, the volume of saline solution and sorption time were the factors optimized applying 24 complete factorial and 23 rotational central composed designs. The linear range of the calibration curve for each PAH was from 10 to 40 ng g−1 and the Pearson correlations for all the compounds were above 0.98. The detection and quantification limits values ranged from 0.13 to 0.46 ng g−1 dry weight and 0.42 to 1.52 ng g−1 dry weight, respectively. The mean recoveries of the spiked samples ranged from 74 ± 16% (acenaphthylene) to 98 ± 5% (fluoranthene) and 84 ± 8% (retene) to 119 ± 6% (9-methylanthracene) for the spiked blanks. Sediment samples show the concentration of PAHs ranged from 0.55 ± 0.04 (naphthalene) to 17.4 ± 0.5 (pyrene) ng g−1 based upon the dry weight.

Determination of N-nitrosamines in Water by Automated Headspace Solid-Phase Microextraction

An automated headspace solid-phase microextraction coupled with gas chromatography–mass spectrometry (automated HS-SPME/GC–MS) for the determination of four N-nitrosamines N-nitroso-di-n-ethylamine, N-nitroso-di-n-propylamine, N-nitrosopiperidine and N-nitroso-di-n-butylamine in groundwater samples was developed. Response surface methodology was employed to optimize relevant extraction parameters including extraction time, sample pH, incubation temperature and salt addition. The optimal HS-SPME were 20 min of extraction time, sample pH of 7, incubation temperature of $$65\,{^{\circ }}\hbox {C}$$ and 30% (w/v) sodium chloride concentration. Under these conditions, good linearity for the analytes in the range from 0.1 to $$100\,\upmu \hbox {g}/\hbox {L}$$ with correlation coefficient (R) from 0.975 to 0.992 was obtained. The limits of detection based on a signal-to-noise ratio of 3 were between 0.78 and 11.92 ng/L with corresponding relative standard deviations from 1.8 to 5.7% $$({n}=4)$$ . The average relative recoveries of the four N-nitrosamines from spiked different groundwater samples by $$1\,\upmu \hbox {g}/\hbox {L}$$ and $$20\,\upmu \hbox {g}/\hbox {L}$$ of each analyte (mean ± standard deviation, $$n=4$$ ) were $$96.6\pm 4.4$$ and $$102.3\pm 4.86\,\%$$ , respectively. The method was applied to determine the N-nitrosamine in groundwater samples from different locations in Saudi Arabia. The average recoveries of spiked N-nitrosamines in different groundwater.

Biodegradation of hydrocarbon mixtures in surface waters at environmentally relevant levels – Effect of inoculum origin on kinetics and sequence of degradation

Biodegradation is a dominant removal process for many organic pollutants, and biodegradation tests serve as tools for assessing their environmental fate within regulatory risk assessment. In simulation tests, the inoculum is not standardized, varying in microbial quantity and quality, thereby potentially impacting the observed biodegradation kinetics. In this study we investigated the effect of inoculum origin on the biodegradation kinetics of hydrocarbons for five inocula from surface waters varying in urbanization and thus expected pre-exposure to petroleum hydrocarbons. A new biodegradation method for testing mixtures of hydrophobic chemicals at trace concentrations was demonstrated: Aqueous solutions containing 9 hydrocarbons were generated by passive dosing and diluted with surface water resulting in test systems containing native microorganisms exposed to test substances at ng-μg/L levels. Automated Headspace Solid Phase Microextraction coupled to GC-MS was applied directly to these test systems to determine substrate depletion relative to abiotic controls. Lag phases were generally less than 8 days. First order rate constants were within one order of magnitude for each hydrocarbon in four of the five waters but lower in water from a rural lake. The sequence of degradation between the 9 hydrocarbons showed similar patterns in the five waters indicating the potential for using selected hydrocarbons for benchmarking between biodegradation tests. Degradation half-times were shorter than or within one order of magnitude of BioHCwin predictions for 8 of 9 hydrocarbons. These results showed that location choice is important for biodegradation kinetics and can provide a relevant input to aquatic exposure and fate models.

Biodegradation testing of chemicals with high Henry's constants – Separating mass and effective concentration reveals higher rate constants

During simulation-type biodegradation tests, volatile chemicals will continuously partition between water phase and headspace. This study addressed how (1) this partitioning affects test results and (2) can be accounted for by combining equilibrium partition and dynamic biodegradation models. An aqueous mixture of 9 (semi)volatile chemicals was first generated using passive dosing and then diluted with environmental surface water producing concentrations in the ng/L to μg/L range. After incubation for 2 h to 4 weeks, automated Headspace Solid Phase Microextraction (HS-SPME) was applied directly on the test systems to measure substrate depletion by biodegradation relatively to abiotic controls. HS-SPME was also applied to determine air to water partitioning ratios. Biodegradation rate constants relating to the chemical in the water phase, kwater, were generally a factor 1 to 11 times higher than biodegradation rate constants relating to the total mass of chemical in the test system, ksystem, with one exceptional factor of 72 times for a long chain alkane. True water phase degradation rate constants were found (i) more appropriate for risk assessment than test system rate constants, (ii) to facilitate extrapolation to other air-water systems and (iii) to be better defined input parameters for aquatic exposure and fate models.

Furan in commercial baby foods from the Spanish market: estimation of daily intake and risk assessment

ABSTRACTThe occurrence of furan in commercial baby food samples from the Spanish market was evaluated using an automated headspace solid-phase microextraction method coupled to gas chromatography-mass spectrometry (HS-SPME-GC-MS). A total of 76 baby food samples including infant formula, baby cereals, fruit in cans and/or jars, vegetables, meat, and fish, were surveyed for furan content. The lowest concentration of this compound was found in infant formula (<0.02–0.33 ng ml−1), and cereal-based food (0.15–2.1 ng g−1) while baby food containing fish showed the highest concentrations (19–84 ng g−1). Following recommendation of the European Food Safety Authority (EFSA), the effect on furan content was evaluated of consumer home preparation of foods, heating and handling. Furan concentrations were reduced by up to 35% when samples were heated in a dish using microwave oven and by up to 53% when a hot water bath was used. Finally, we estimated the furan intake from baby food consumption (0.002–1.18 µg kg−1 body weight day−1) and we calculated the margin of exposure (MOE) from samples as purchased and also after home preparation of the food. For infant formula and cereal baby foods, the MOEs (26,278–412,776) indicated no infant health concern or priority, while for meat and fish-based baby foods the values pointed to a potential public health risk, even considering the furan losses during preparation at home.

Optimisation and validation of a HS-SPME–GC–IT/MS method for analysis of carbonyl volatile compounds as biomarkers in human urine: Application in a pilot study to discriminate individuals with smoking habits

A new and simple analytical approach consisting of an automated headspace solid-phase microextraction (HS-SPME) sampler coupled to gas chromatography-ion trap/mass spectrometry detection (GC–IT/MS) with a prior derivatization step with O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine hydrochloride (PFBHA) was developed to detect volatile carbonyl metabolites with low molecular weights in human urine. A central composite design (CCD) was used to optimise the PFBHA concentration and extraction conditions that affect the efficiency of the SPME procedure. With a sample volume of 1mL, optimal conditions were achieved by adding 300mg/L of PFBHA and allowing the sample to equilibrate for 6min at 62°C and then extracting the samples for 51min at the same temperature, using a divinylbenzene/polydimethylsiloxane (DVB/PDMS) fibre. The method allowed the simultaneous identification and quantification of 44 carbonyl compounds consisting of aldehydes, dialdehydes, heterocyclic aldehydes and ketones. The method was validated with regards to the linearity, inter- and intra-day precision and accuracy. The detection limits ranged from 0.009 to 0.942ng/mL, except for 4-hydroxy-2-nonenal (15ng/mL), and the quantification limits varied from 0.029 to 1.66ng/mL, except for butanal (2.78ng/mL), 2-butanone (2.67ng/mL), 4-heptanone (3.14ng/mL) and 4-hydroxy-2-nonenal (50.0ng/mL). The method accuracy was satisfactory, with recoveries ranging from 90 to 107%. The proof of applicability of the methodology was performed in a pilot target analysis of urine samples obtained from 18 healthy smokers and 18 healthy non-smokers (control group). Chemometric supervised analysis was performed using the volatile patterns acquired for these samples and clearly showed the potential of the volatile carbonyl profiles to discriminate urine from smoker and non-smoker subjects. 5-Methyl-2-furfural (p<0.0001), 2-methylpropanal, nonanal and 2-methylbutanal (p<0.05) were identified as potentially useful biomarkers to identify smoking habits.

Effect of pulsed electric fields on the flavour profile of red-fleshed sweet cherries (Prunus avium var. Stella).

The aim of this research was to study the effect of pulsed electric fields (PEF) on the flavour profile of red-fleshed sweet cherries (Prunus avium variety Stella). The cherry samples were treated at a constant pulse frequency of 100 Hz, a constant pulse width of 20 μs, different electric field strengths between 0.3 and 2.5 kV/cm and specific energy ranging from 31 to 55 kJ/kg. Volatile compounds of samples were analysed using an automated headspace solid phase microextraction (HS–SPME) method coupled with gas chromatography-mass spectrometry (GC–MS). A total of 33 volatile compounds were identified with benzaldehyde, hexanal, (E)-2-hexenal, (Z)-2-hexen-1-ol, and benzyl alcohol being the predominant volatiles in different PEF-treated samples. Aldehydes namely butanal, octanal, 2-octenal, and nonanal, and (Z)-2-hexen-1-ol increased significantly 24 h after PEF treatment at electric field strengths of more than 1.0 kV/cm. Samples incubated for 24 h after PEF treatment (S3) generated higher concentrations of volatiles than samples immediately after PEF treatments (S2). Quantitative results revealed that more flavour volatiles were released and associated with S3 samples after 24 h storage and S2 samples immediately after PEF both with the highest electric field intensities. Interestingly, this study found that the PEF treatments at the applied electric field strength and energy did not result in releasing/producing undesirable flavour compounds.

Automated headspace solid-phase microextraction and on-fiber derivatization for the determination of clenbuterol in meat products by gas chromatography coupled to mass spectrometry.

A method was developed for the determination of clenbuterol in meat using stable-isotope-dilution gas chromatography with mass spectrometry coupled with solid-phase microextraction and on-fiber derivatization. The samples were first homogenized with hydrochloric acid followed by protein deposition. After headspace solid-phase microextraction and on-fiber derivatization, the content of clenbuterol was measured with the aid of stable-isotope dilution. The condition of solid-phase microextraction was optimized by central composite design. The relative standard deviations, limit of detection, and recoveries for clenbuterol were 4.2-9.2%, 0.48 μg/kg, and 96-104%, respectively. The proposed method was satisfactory for analysis of real samples as compared with the Chinese standard method.

An automated headspace solid-phase microextraction followed by gas chromatography–mass spectrometry method to determine macrocyclic musk fragrances in wastewater samples

A fully automated method has been developed for determining eight macrocyclic musk fragrances in wastewater samples. The method is based on headspace solid-phase microextraction (HS-SPME) followed by gas chromatography–mass spectrometry (GC-MS). Five different fibres (PDMS 7 μm, PDMS 30 μm, PDMS 100 μm, PDMS/DVB 65 μm and PA 85 μm) were tested. The best conditions were achieved when a PDMS/DVB 65 μm fibre was exposed for 45 min in the headspace of 10 mL water samples at 100 °C. Method detection limits were found in the low ng L−1 range between 0.75 and 5 ng L−1 depending on the target analytes. Moreover, under optimized conditions, the method gave good levels of intra-day and inter-day repeatabilities in wastewater samples with relative standard deviations (n =5, 1,000 ng L−1) less than 9 and 14 %, respectively. The applicability of the method was tested with influent and effluent urban wastewater samples from different wastewater treatment plants (WWTPs). The analysis of influent urban wastewater revealed the presence of most of the target macrocyclic musks with, most notably, the maximum concentration of ambrettolide being obtained in WWTP A (4.36 μg L−1) and WWTP B (12.29 μg L−1), respectively. The analysis of effluent urban wastewater showed a decrease in target analyte concentrations, with exaltone and ambrettolide being the most abundant compounds with concentrations varying between below method quantification limit (<MQL) and 2.46 μg L−1.

Optimization of the HS-SPME–GC–IT/MS method using a central composite design for volatile carbonyl compounds determination in beers

An automated headspace solid-phase microextraction (HS-SPME) combined with gas chromatography and ion trap mass spectrometry detection (GC-IT/MS) was developed in order to quantify a large number of carbonyl compounds in beers. Carbonyl compounds were previously derivatized with O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine hydrochloride (PFBHA). Volatile carbonyl compounds associated with staling beer aroma includes alkanals, alkenals, alkadienals, dicarbonyl compounds, Strecker aldehydes, ketones and furans. The HS-SPME was performed using a polydimethylsiloxane/divinylbenzene (PDMS/DVB) fiber. The procedures were optimized for HS-SPME pre-incubation temperature and time, extraction temperature and time, and PFBHA addition. A central composite design was used in the optimization of extraction conditions and PFBHA addition. The volatile compounds showed optimal extraction incubating 5 ml of beer with 700 mg l(-1) of PFBHA for 7 min and extracted for more 20 min at 45 °C. The method was validated with regard to the linearity, repeatability, inter and intra-day precision and accuracy. The method achieved detection limits ranging from 0.003 to 0.510 µg l(-1), except for furans (1.54-3.44 µg l(-1)). The quantification limits varied from 0.010 to 1.55 µg l(-1), except for 2-furfural (4.68 µg l(-1)), 5-methyl-2-furfural (5.82 µg l(-1)) and 5-hyfroxymethylfurfural (10.4 µg l(-1)). Repeatability values of all compounds were lower than 17%. The method accuracy was satisfactory with recoveries ranging from 88% to 114%. The validated method showed to be suitable for a fast and reliable determination of main carbonyl compounds in beers.

Automated SPME–GC–MS monitoring of headspace metabolomic responses of E. coli to biologically active components extracted by the coating

Monitoring extracellular metabolites of bacteria is very useful for not only metabolomics research but also for assessment of the effects of various chemicals, including antimicrobial agents and drugs. Herein, we describe the automated headspace solid-phase microextraction (HS-SPME) method coupled with gas chromatography–mass spectrometry (GC–MS) for the qualitative as well as semi-quantitative determination of metabolic responses of Escherichia coli to an antimicrobial agent, cinnamaldehyde. The minimum inhibitory concentration of cinnamaldehyde was calculated to be 2gL−1. We found that cinnamaldehyde was an important factor influencing the metabolic profile and growth process. A higher number of metabolites were observed during the mid-logarithmic growth phase. The metabolite variations (types and concentrations) induced by cinnamaldehyde were dependent on both cell density and the dose of cinnamaldehyde. Simultaneously, 25 different metabolites were separated and detected (e.g., indole, alkane, alcohol, organic acids, esters, etc.) in headspace of complex biological samples due to intermittent addition of high dose of cinnamaldehyde. The study was done using an automated system, thereby minimizing manual workup and indicating the potential of the method for high-throughput analysis. These findings enhanced the understanding of the metabolic responses of E. coli to cinnamaldehyde shock effect and demonstrated the effectiveness of the SPME–GC–MS based metabolomics approach to study such a complex biological system.

Application of automated solid-phase microextraction to determine haloacetonitriles, haloketones, and chloropicrin in Canadian drinking water

An automated headspace solid-phase microextraction gas chromatography mass spectrometry (HS-SPME-GC-MS) method was developed to monitor the occurrence of selected haloacetonitriles (HANs), haloketones (HKs), and chloropicrin (CP) in drinking water supplies. The method was rapid with analysis time of 30 min, including extraction and chromatographic run. Chemical ionization (CI) was used to increase the sensitivity of the method for the HKs. SPME fibers with seven different coatings including commercial polyacrylate (PA), carbowax/divinylbenzene (CW/DVB), polydimethylsiloxane (PDMS), polydimethylsiloxane/divinylbenzene (PDMS/DVB), carboxen/polydimethylsiloxane (CAR/PDMS), divinylbenzene/carboxen/polydimethylsiloxane (DVB/CAR/PDMS), and a novel custom-made polydimethylsiloxane/divinylbenzene-N-vinylpyrrolidone (PDMS/DVB-NVP) were evaluated. The DVB/CAR/PDMS fiber was found more suitable for the range of the analytes and the novel PDMS/DVB-NVP fiber more efficient for the brominated acetonitriles under the experimental conditions. Method detection limits (MDLs) for the chlorinated acetonitriles and CP varied between 2 and 40 ng/L and for the brominated acetonitriles and HKs between 100 and 180 ng/L. Relative standard deviations (RSD %) of measurements were 4–7%. The method was applied in parallel with a liquid–liquid extraction gas chromatography electron capture detection (LLE-GC-ECD) method (EPA Method 551.1) to the analysis of drinking water samples from eight Canadian water treatment and distribution systems. The results generated by the two methods showed good agreement.

Characterizing the Chemical and Sensory Profiles of United States Cabernet Sauvignon Wines and Blends

Cabernet Sauvignon is one of the most reputable red grape varieties grown in the United States; however, limited information is available on the chemical and sensory composition of the resulting wines. The purpose of this study was to develop a rapid, targeted profiling method for measuring volatile compounds with sensory impact in U.S. Cabernet Sauvignon wines and blends. We developed a semiquantitative, automated headspace solid-phase microextraction (HS-SPME) gas chromatography–mass spectrometry (GC-MS) method combined with synchronous selected ion monitoring (SIM)/scan detection to measure 61 volatile compounds. The compounds monitored included grape-derived norisoprenoids and terpenes; fermentation-derived esters, higher alcohols, and aldehydes; Brettanomyces-related compounds; and oak-derived compounds. Methoxypyrazine was also measured using HS-SPME-GC-MS/MS. Twenty-four commercial U.S. Cabernet Sauvignon varietal and blended wines from several regions in California and Washington State were selected to encompass a broad range of wine styles and were analyzed using the GC methods developed. The results were compared to a descriptive sensory analysis of the wines using 11 trained assessors to determine the extent to which the chemical analyses could predict sensory profiles. The rapid, targeted profiling method was able to predict a number of aroma sensory descriptors. The Cabernet Sauvignon wines and blends differed in their chemical and sensory profiles and were differentiated, in part, as a result of the direct and indirect influences of varying alcohol levels. This work provides the wine industry with the ability to rapidly assess wine volatile composition in order to further elucidate the relationships between the chemical compounds and sensory profiles of wines.

Analysis of corky off-flavour compounds at ultra trace level with multidimensional gas chromatography-electron capture detection

A robust method for routine quality control of corky off-flavour compounds in wine and cork soak matrices has been established. Based on an automated headspace solid phase microextraction (HS-SPME), the method needs only marginal sample preparation and achieves low (sub-ngL−1) trace level detection limits (LODs) for the most relevant off-flavour compounds, such as 2,4,6-trichloroanisole (TCA), 2,3,4,6-tetrachloroanisole (TeCA) and 2,4,6-tribromoanisole (TBA). Particularly for wine matrix, reliable trace level quantification had only been achieved after applying heart-cutting multidimensional gas chromatography (MDGC). Using a halogen-sensitive electron capture detector (ECD) and quantification with a stable isotope dilution assay (SIDA), LODs of 0.1ngL−1 for TCA, TeCA and TBA could be obtained. Since a SIDA based quantification method is used with a non-mass spectrometric detector, the necessary chromatographic resolution of internal standard and target analyte peaks resulted from the use of highly deuterated [2H5]-isotopologues.

Development and validation of automatic HS-SPME with a gas chromatography-ion trap/mass spectrometry method for analysis of volatiles in wines

An automated headspace solid-phase microextraction (HS-SPME) combined with gas chromatography-ion trap/mass spectrometry (GC-IT/MS) was developed in order to quantify a large number of volatile compounds in wines such as alcohols, ester, norisoprenoids and terpenes. The procedures were optimized for SPME fiber selection, pre-incubation temperature and time, extraction temperature and time, and salt addition. A central composite experimental design was used in the optimization of the extraction conditions. The volatile compounds showed optimal extraction using a DVB/CAR/PDMS fiber, incubation of 5ml of wine with 2g NaCl at 45°C during 5min, and subsequent extraction of 30min at the same temperature. The method allowed the identification of 64 volatile compounds. Afterwards, the method was validated successfully for the most significant compounds and was applied to study the volatile composition of different white wines.

Simultaneous analysis of 10 trihalomethanes at nanogram per liter levels in water using solid-phase microextraction and gas chromatography mass-spectrometry

Trihalomethanes are predominantly formed during disinfection of water via reactions of the oxidant with natural organic matter. Even though chlorinated and brominated trihalomethanes are the most widespread organic contaminants in drinking water, when iodide is present in raw water iodinated trihalomethanes can also be formed. The formation of iodinated trihalomethanes can lead to taste and odor problems and is a potential health concern since they have been reported to be more toxic than their brominated or chlorinated analogs. Currently, there is no published standard analytical method for I-THMs in water. The analysis of 10 trihalomethanes in water samples in a single run is challenging because the iodinated trihalomethanes are found at very low concentrations (ng/L range), while the regulated chlorinated and brominated trihalomethanes are present at much higher concentrations (above μg/L). An automated headspace solid-phase microextraction technique, with a programmed temperature vaporizer inlet coupled with gas chromatography-mass spectrometry, was developed for routine analysis of 10 trihalomethanes i.e. bromo-, chloro- and iodo-trihalomethanes in water samples. The carboxen/polydimethylsiloxane/divinylbenzene fiber was found to be the most suitable. The optimization, linearity range, accuracy and precision of the method are discussed. The limits of detection range from 1ng/L to 20ng/L for iodoform and chloroform, respectively. Matrix effects in treated groundwater, surfacewater, seawater, and secondary wastewater were investigated and it was shown that the method is suitable for the analysis of trace levels of iodinated trihalomethanes in a wide range of waters. The method developed in the present study has the advantage of being rapid, simple and sensitive. A survey conducted throughout various process stages in an advanced water recycling plant showed the presence of iodinated trihalomethanes at ng/L levels.

Determination of fifteen active compounds released from paraffin-based active packaging in tomato samples via microextraction techniques

Automated headspace solid-phase microextraction (HS-SPME) and hollow-fibre liquid-phase microextraction (HFLPME) methods for the determination of 15 active chemicals released from essential-oil-based active packaging have been considered. The HS-SPME procedure demonstrates good performance and was therefore optimised and validated, providing detection limits in the low microgram per kilogramme range and wide and convenient linear ranges from 40.0 to 900.0 microg/kg. Extraction temperature has been demonstrated to be the most critical experimental parameter requiring accurate monitoring.

Automated headspace solid-phase microextraction versus headspace for the analysis of furan in foods by gas chromatography–mass spectrometry

A simple, fast and fully automated method based on headspace solid-phase microextraction coupled on-line with gas chromatography–ion trap mass spectrometry (HS-SPME–GC–ITMS) is proposed for furan determination in foods. The performance of the proposed method was compared to the automated headspace-GC–MS method, proposed by the US Food and Drugs Administration (US FDA), in terms of repeatability, limits of the detection and quantification. Both methods gave similar results for furan determination in selected food samples, although slightly worse precision (RSD%, 9–12%) and higher limits of detection (from 5 to 20 times higher) were obtained by the headspace method. In addition, higher sample throughput in routine furan analysis was obtained using the proposed HS-SPME–GC–ITMS method with isotope dilution than using the US FDA method, which recommends standard addition for quantification. The proposed method provides good precision (RSD% <10%) and low limits of detection, ranging from 0.02 to 0.12 ng g −1 depending on the sample. The developed HS-SPME–GC–MS method was used to analyse furan in several Spanish food commodities and concentrations ranging from 0.1 ng g −1 to 1.1 μg g −1 were found.