Coacervative microextraction ultrasound-assisted back-extraction technique for determination of organophosphates pesticides in honey samples by gas chromatography–mass spectrometry

Coacervative microextraction ultrasound-assisted back-extraction technique (CME-UABE) is proposed for the first time for extracting and preconcentrating organophosphates pesticides (OPPs) from honey samples prior to gas chromatography–mass spectrometry (GC–MS) analysis. The extraction/preconcentration technique is supported on the micellar organized medium based on non-ionic surfactant. To enable coupling the proposed technique with GC, it was required to back extract the analytes into hexane. Several variables including, surfactant type and concentration, equilibration temperature and time, matrix modifiers, pH and buffers nature were studied and optimized over the relative response of the analytes. The best working conditions were as follows: an aliquot of 10 mL 50 g L⁻¹ honey blend solution was conditioned by adding 100 μL 0.1 mol L⁻¹ hydrochloric acid (pH 2) and finally extracted with 100 μL Triton X-114 100 g L⁻¹ at 85 °C for 5 min using CME technique. Under optimal experimental conditions, the enrichment factor (EF) was 167 and limits of detection (LODs), calculated as three times the signal-to-noise ratio (S/N = 3), ranged between 0.03 and 0.47 ng g⁻¹. The method precision was evaluated over five replicates at 1 ng g⁻¹ with RSDs ≤9.5%. The calibration graphs were linear within the concentration range of 0.3–1000 ng g⁻¹ for chlorpirifos; and 1–1000 ng g⁻¹ for fenitrothion, parathion and methidathion, respectively. The coefficients of correlation were ≥0.9992. Validation of the methodology was performed by standard addition method at two concentration levels (2 and 20 ng g⁻¹). The recoveries were ≥90%, indicating satisfactory robustness of the methodology, which could be successfully applied for determination of OPPs in honey samples of different Argentinean regions. Two of the analyzed samples showed levels of methidathion ranged between 1.2 and 2.3 ng g⁻¹.     

One-step extraction and derivatization liquid-phase microextraction for the determination of chlorophenols by gas chromatography–mass spectrometry

A sample pretreatment method for the determination of 18 chlorophenols (CPs) in aqueous samples by derivatization liquid-phase microextraction (LPME) was investigated using gas chromatography–mass spectrometry. Derivatization reagent was spiked into the extraction solvent to combine derivatization and extraction into one step. High sensitivity of 18 CPs derivatives could be achieved after optimization of several parameters such as extraction solvent, percentage of derivatization reagent, extraction time, pH, and ionic strength. The results from the optimal method showed that calibration ranging from 0.5 to 500 μg L⁻¹ could be achieved with the RSDs between 1.75% and 9.39%, and the limits of detection (LOD) are ranging from 0.01 to 0.12 μg L⁻¹ for the CPs. Moreover, the proposed LPME method was compared with solid-phase microextraction (SPME) coupled with on-fiber derivatization technique. The results suggested that using both methods are quite agreeable. Furthermore, the recoveries of LPME evaluated by spiked environmental samples ranged from 87.9% (3,5-DCP) to 114.7% (2,3,5,6-TeCP), and environmental water samples collected from the Pearl River were analyzed with the optimized LPME method, the concentrations of 18 CPs ranged from 0.0237 μg L⁻¹ (3,5-DCP) to 0.3623 μg L⁻¹ (2,3,6-TCP).     

Single-drop microextraction and gas chromatography–mass spectrometry for the determination of volatile aldehydes in fresh cucumbers

Headspace single-drop microextraction (HS-SDME) was used as a rapid and reliable method for the isolation and preconcentration of volatile aldehydes from fresh cucumbers. The utility of this methodology is demonstrated in the determination of (E)-2-nonenal and (E,Z)-2,6-nonadienal. The limit of detection, linearity and repeatability have been determined for 2,6-nonadienal and (E)-2-nonenal. Limits of detection for nonenal and nonadienal were 0.05 and 0.04 mg kg ⁻¹, respectively. The repeatability of extraction was obtained with the RSD values lower than 13%. Concentrations of target aldehydes in fresh cucumbers obtained by means of the HS-SDME method were in the range 9.4–12.5 (nonadienal) and 2.6–3.8 mg kg ⁻¹ (nonenal). The results of the single-drop extraction in combination with gas chromatography show promising potential for the analysis of volatile aldehydes in vegetables. Presented at the 11th International Conference on Chemistry and the Environment, 9-12 September 2007, Torun, Poland.     

Multi-residue determination of organochlorine pesticides in vegetables in Kirklareli,Turkey by gas chromatography–mass spectrometry

The aim of this study was to investigate the level of organochlorine pesticides use for treatment of tomatoes, eggplants and cucumbers in Kirklareli, Turkey. Eighteen organochlorine pesticides were identified in vegetable samples using microwave or Soxhlet extraction, and results were obtained by gas chromatography–mass spectrometry. The optimized conditions were 1 mL/min for flow rate in the mobile phase, 1 μL for injection volume and 70 V for fragmentation potential. The analytical parameters show that the microwave oven extraction procedure provided the best results when compared to the Soxhlet extraction procedure. Samples were prepared for analysis with hexane?dichlormethane (1: 1, v/v, 40 mL) using a solid-phase extraction method. The limits of detection and quantitation for the eighteen analytes were between 0.02–0.26 and 0.06–0.87 μg/L, respectively, and the relative standard deviations of the migration time ranged from 2.4 to 8.9%. The recoveries of surrogate spiked in vegetable samples ranged from 70 to 116%, respectively. The obtained concentrations of pesticides in all vegetables studied were proved in the range of ND–123 μg/kg. The organochlorine pesticide sum was below the legal limit, except for Endrin and Methoxychlor, which requires a further elucidation of the organochlorine pesticides pollution sources in the region. These studies on accumulation of organochlorine pesticides were necessary for accomplishing a comprehensive ecological risk assessment.     

Single-drop microextraction with in-microvial derivatization for the determination of haloacetic acids in water sample by gas chromatography–mass spectrometry

A new approach using single-drop microextraction (SDME) and gas chromatography–mass spectrometry for the determination of six haloacetic acids (HAAs) in water samples was presented. n-Octanol was used as extractant and derivatization reagent. HAAs were derivatized both simultaneously during the extraction in the solvent microdrop, and after extraction, inside a glass microvial (1.1 mm I.D.). Trifluoroacetic anhydride (TFAA) was used as the reaction catalyst. The influence of catalyst amount, derivatization time and temperature on the yield of the in-microvial derivatization was investigated. Derivatization reaction was performed using 1.2 μL of TFAA at 100 °C for 20 min. Extraction was performed using 1.8 μL of n-octanol containing TFAA (10%, v/v). Experimental parameters, such as, exposure time, sample pH and extraction temperature were controlled and optimized. Analytical parameters such as linearity, precision and limit of detection were also evaluated. The proposed method was proved to be a suitable analytical procedure for HAAs in water with limits of detection 0.1–1.2 μg/L. The relative recoveries range from 82.5 to 97.6% for all the target analytes. Precision values were from 5.1 to 8.5% (as intra-day relative standard deviation, RSD) and 8.8–12.3% (as inter-day RSD).     

Method development for the determination of 52 pesticides in tobacco by liquid chromatography–tandem mass spectrometry

A method using reversed phase liquid chromatography–electrospray ionization–tandem mass spectrometry was developed for the determination of 52 pesticides in tobacco. The influence of mobile phase additives was investigated to improve sensitivity and accuracy of the method and to reduce matrix effects. The tobacco extracts were purified via a Chem Elut partition cartridge by consecutive elution with pentane followed by dichloromethane. The two fractions were further purified by Florisil solid-phase extraction with acetone or diethyl ether elution. An additional dispersive solid-phase extraction step with primary–secondary amine led to decreased recoveries of several pesticides due to degradation or binding to the sorbent. The method was validated for the tobacco types Burley, Oriental and Virginia. The recovery rates of almost all pesticides ranged between 70 and 120%. The limits of quantification were below or near the 10 ng/g level. Few but significant differences between the tobacco types could be found regarding recovery and sensitivity.     

Application of SiO2 hollow fibers for sorptive microextraction and gas chromatography–mass spectrometry determination of organochlorine pesticides in herbal matrices

A method involving simultaneous extraction and sample clean-up procedure: hollow fiber sorptive microextraction, coupled with gas chromatography–mass spectrometric detection for quantification of seven organochlorine pesticides in Radix et Rhizoma Rhei is described. SiO₂ hollow fiber with porous structure was synthesized for the first time. The internal diameter of SiO₂ hollow fiber is 380 μm and average wall thickness is 100 μm. Aggregated SiO₂ particles deposited on the surface of the hollow fiber in a regular array lead to porous structure. SiO₂ hollow fiber was applied to the determination of organochlorine pesticides in Radix et Rhizoma Rhei to avoid sample clean-up and minimize the matrix effects. Extraction solvent, extraction temperature and equilibration time were optimized. Fiber to fiber repeatability over the concentration ranges were less than 10%. Recoveries were satisfactory (between 63% and 115%) for most of organochlorine pesticides at spiking levels. Furthermore, the proposed method was also applied to determine seven organochlorine pesticides in 43 commercial Radix et Rhizoma Rhei samples, in which the selected pesticides were found in eight samples. The results have been further confirmed by solvent extraction methods according to China Pharmacopoeia (2005).     

Analytical determination of nicotine in tobacco leaves by gas chromatography–mass spectrometry

A preliminary investigation using gas chromatography–mass spectrometry (GC–MS) to analyze the nicotine contained in tobacco leaves was carried out. Nicotine is an alkaloid and tobacco leaves was extracted with methanol and determined by GC–MS. The detection limit for nicotine was at the ppm level for non selective monitoring and the nanogram level for selective detection. This is a simple chromatography–mass spectrometry method for the analysis of nicotine in tobacco leave. Compared to other currently utilized methods for the detection of nicotine in tobacco leaves, the GC–MS provided advantages of high sensitivity, nicotine specific detection and lower instrumentation cost.     

Analysis of carbamate pesticides in water samples using single-drop microextraction and gas chromatography–mass spectrometry

Single-drop microextraction (SDME) followed by gas chromatography–mass spectrometry detection was used for the determination of some carbamate pesticides in water samples. The studied pesticides were thiofanox, carbofuran, pirimicarb, methiocarb, carbaryl, propoxur, desmedipham and phenmedipham. Two alternative sample introduction methods have been examined and compared; SDME followed by cool on-column injection (without derivatization) and SDME followed by in-microvial derivatization and splitless injection. Acetic anhydride was used as derivatization reagent. Parameters that affect the derivatization reaction yield and the extraction efficiency of the SDME method were studied and optimized. The analytical performances and possible applications of both approaches were investigated. Relative standard deviations for the studied compounds ranged from 3.2 to 8.3%. The detection limits obtained by the derivatization method were found to be in the range 3–35 ng/L. Using cool on-column injection (without derivatization), the detection limits were between 30 and 80 ng/L.     

Fast analysis of multiple pesticide residues in apple juice using dispersive liquid–liquid microextraction and multidimensional gas chromatography–mass spectrometry

A method for the rapid trace analysis of 24 residual pesticides in apple juice by multidimensional gas chromatography–mass spectrometry (MD-GC/MS) using dispersive liquid–liquid microextraction (DLLME) was developed and optimized. Several parameters of the extraction procedure such as type and volume of extraction solvent, type and volume of dispersive solvent and salt addition were evaluated to achieve the highest yield and to attain the lowest detection limits. The DLLME procedure optimized consists in the formation of a cloudy solution promoted by the fast addition to the sample (5 ml) of a mixture of carbon tetrachloride (extraction solvent, 100 μl) and acetone (dispersive solvent, 400 μl). The tiny droplets formed and dispersed among the aqueous sample solution are further joined and sedimented (85 μl) in the bottom of the conical test tube by centrifugation. Once extracted, all the 24 pesticides were directly injected and separated by a dual GC column system, comprising a short wide-bore DB-5 capillary column with low film thickness connected by a Deans switch system to a second chromatographic narrower column, with identical stationary phase. The instrumental setting used, in combination with carefully optimized operational fast GC and MS parameters, markedly decreased the retention times of the targeted analytes. The total chromatographic run was 8 min. Mean recoveries for apple juice spiked at three concentrations ranged from 60% to 105% and the intra-repeatability ranged from 1% to 21%. The limits of detection of the 24 pesticides ranged from 0.06 to 2.20 μg/L. In 2 of a total of 28 analysed samples were found residues of captan, although at levels below the maximum limit legal established.     

Development of a simple extraction and clean-up procedure for determination of organochlorine pesticides in soil using gas chromatography–tandem mass spectrometry

A procedure based on QuEChERS extraction and a simultaneous liquid–liquid partition clean-up was developed. The procedure involved extraction of hydrated soil samples using acetonitrile and clean-up by liquid–liquid partition into n-hexane. The hexane extracts produced were clean and suitable for determination using gas chromatography–tandem mass spectrometry (GC–MS/MS). The method was validated by analysis of soil samples, spiked at five levels between 1 and 200 μg kg⁻¹. The recovery values were generally between 70 and 100% and the relative standard deviation values (%RSDs) were at or below 20%. The procedure was validated for determination of 19 organochlorine (OC) pesticides. These were hexachlorobenzene (HCB), α-HCH, β-HCH, γ-HCH, heptachlor, heptachlor epoxide (trans), aldrin, dieldrin, chlordane (trans), chlordane (cis), oxychlordane, α-endosulfan, β-endosulfan, endosulfan sulfate, endrin, p,p′-DDT, o,p′-DDT, p,p′-DDD and p,p′-DDE. The method achieved low limits of detection (LOD; typically 0.3 μg kg⁻¹) and low limits of quantification (LOQ; typically 1.0 μg kg⁻¹). The method performance was also assessed using five fortified soil samples with different physico-chemical properties and the method performance was consistent for the different types of soil samples. The proposed method was compared with an established procedure based on Soxtec extraction. This comparison was carried out using six soil samples collected from regions of Pakistan with a history of intensive pesticide use. The results of this comparison showed that the two procedures produced results with good agreement. The proposed method produced cleaner extracts and therefore led to lower limits of quantification. The proposed method was less time consuming and safer to use. The six samples tested during this comparison showed that soils from cotton growing regions contained a number of persistent OC residues at relatively low levels (<10 μg kg⁻¹). These residues were α-HCH, γ-HCH, heptachlor, chlordane (trans), p,p′-DDT, o,p′-DDT, p,p′-DDD, p,p′-DDE, β-endosulfan and endosulfan sulfate.     

Simple approach based on ultrasound-assisted emulsification-microextraction for determination of polibrominated flame retardants in water samples by gas chromatography–mass spectrometry

A simple, efficient, innovative and environmentally friendly analytical technique was successfully applied for the first time for the extraction and preconcentration of polybrominated diphenyl ethers (PBDEs) from water samples. The PBDEs selected for this work were those most commonly found in the literature in natural water samples: 2,2′,4,4′-tetraBDE (BDE-47), 2,2′,4,4,5-pentaBDE (BDE-99), 2,2′,4,4,6-pentaBDE (BDE-100) and 2,2,4,4′,5,5′-hexaBDE (BDE-153). The extracted PBDEs were separated and determined by gas chromatography–mass spectrometry (GC–MS). The extraction/preconcentration technique is based on ultrasound-assisted emulsification-microextraction (USAEME) of a water-immiscible solvent in an aqueous medium. Several variables including, solvent type, extraction time, extraction temperature and matrix modifiers were studied and optimized over the relative response the target analytes. Chloroform was used as extraction solvent in the USAEME technique. Under optimum conditions, the target analytes were quantitatively extracted achieving enrichment factors (EF) higher than 319. The detection limits (LODs) of the analytes for the preconcentration of 10 mL sample volume were within the range 1–2 pg mL⁻¹. The relative standard deviations (RSD) for five replicates at 10 pg mL⁻¹ concentration level were <10.3%. The calibration graphs were linear within the concentration range of 5–5000 pg mL⁻¹ for BDE-47 and BDE-100; and 5–10,000 pg mL⁻¹ for BDE-99 and BDE-153, respectively. The coefficients of estimation were ≥0.9985. Validation of the methodology was performed by standard addition method at two concentration levels (10 and 50 pg mL⁻¹). Recovery values were ≥96%, which showed a successful robustness of the analytical methodology for determination of picogram per milliliter of PBDEs in water samples. Significant quantities of PBDEs were not found in the analyzed samples.     

Development of a gas chromatography — mass spectrometry method for the determination of carbon disulfide in the atmosphere

Carbon disulfide (CS₂), a relevant reduced sulfur compound in air, is well-known for its malodor and its significant effect on global atmospheric chemistry. Therefore, a reliable method for determining CS₂ in atmospheric samples has been developed based on solid-phase sampling and gas chromatography–mass spectrometry (GC–MS). Two types of solid-phase sampling supports (Orbo-32 and SKC) and the elution with organic solvents — hexane and toluene — were evaluated for low-volume outdoor sampling. Recovery studies and the standard addition method were carried out to demonstrate the proper determination of CS₂ in the absence of the influence of interferences such as ozone, hydrogen sulfide or water — important atmospheric pollutants —. The proposed methodology was validated by performing experiments in a high-volume smog chamber and by comparison with two reference optical methods, Fourier Transform Infrared (FTIR) and Differential Optical Absorption Spectroscopy (DOAS) installed in these facilities. Satisfactory analytical parameters were reported: fast analysis, a correct repeatability of 6 ± 1% and reproducibility of 14 ± 3%, and low detection limits of 0.3–0.9 pg m^? 3. Finally, the method was successfully applied to industrial samples near a pulp factory area, where a high correlation between industrial emissions and reported carbon disulfide concentrations were observed.     

Fast low-pressure gas chromatography–mass spectrometry method for the determination of multiple pesticides in grapes,musts and wines

A fast method using low-pressure gas chromatography coupled to mass spectrometry (LP-GC/MS) was implemented and optimized to yield a complete separation of 27 representative pesticides in grapes, musts and wines. Extraction was performed with acetonitrile, applying quick, easy, cheap, effective, rugged and safe (QuEChERS) methodology. Several LP-GC/MS conditions such as column temperature, injection conditions, flow rate, MS conditions and matrix effects were evaluated to achieve the fastest separation with the highest sensitivity in MS detection (selected ion monitoring mode). After optimization, all 27 pesticides were extracted, chromatographically separated and detected in less than 20 min. Acceptable recoveries for nearly all pesticides at three different spiking levels (from 0.04 to 2.5 μg/g) were achieved with good repeatability (from 3 to 21%). Limits of quantification (from 0.02 to 5 μg/g) were lower than the maximum limit of residues, when established for pesticides.     

Monitoring chlorophenols in industrial effluents by solid-phase microextraction–gas chromatography–mass spectrometry

A method for the determination of 19 chlorophenols in industrial effluents samples using solid-phase microextraction (SPME) coupled to gas chromatography–mass spectrometry has been developed. Four kinds of different SPME fibres have been studied. Among them, the polyacrylate and carbowax®-divinylbenzene fibres were the most adequate. The extraction process was optimized by means of the experimental design, which allows the study of a large number of factors with a reasonable number of experiments. The optimized method allows the determination of the studied chlorophenols in complex matrices with a high organic content with detection limits down to 0.07?ng?mL^?1 and RSD ranging from 4.4% to 13.8%. The recovery studies with spiked real effluent samples at low levels of chlorophenols ranged from 59.8% to 142.1% for the lowest level (0.5?ng?mL^?1) and from 79.6% to 115.8% for the highest spiked level (2?ng?mL^?1). These results show the suitability of the proposed method to monitor chlorophenols in complex samples. 2,4,5-TCP was detected at concentrations close to its limits of detection in effluents coming from an oil refinery.     

Solvent-based de-emulsification dispersive liquid–liquid microextraction combined with gas chromatography–mass spectrometry for determination of trace organochlorine pesticides in environmental water samples

In this work, we propose solvent-based de-emulsification dispersive liquid–liquid microextraction (SD-DLLME) as a simple, rapid and efficient sample pretreatment technique for the extraction and preconcentration of organochlorine pesticides (OCPs) from environmental water samples. Separation and analysis of fifteen OCPs was carried out by gas chromatography–mass spectrometry (GC/MS). Parameters affecting the extraction efficiency were systematically investigated. The detection limits were in the range of 2–50 ng L⁻¹ using selective ion monitoring (SIM). The precision of the proposed method, expressed as relative standard deviation, varied between 3.5 and 10.2% (n = 5). Results from the analysis of spiked environmental water samples at the low-ppb level met the acceptance criteria set by the EPA.     

Pre-concentration of phenolic compounds in water samples by novel liquid–liquid microextraction and determination by gas chromatography–mass spectrometry

Pre-concentration and determination of 8 phenolic compounds in water samples has been achieved by in situ derivatization and using a new liquid–liquid microextraction coupled GC–MS system. Microextraction efficiency factors have been investigated and optimized: 9 μL 1-undecanol microdrop exposed for 15 min floated on surface of a 10 mL water sample at 55 °C, stirred at 1200 rpm, low pH level and saturated salt conditions. Chromatographic problems associated with free phenols have been overcome by simultaneous in situ derivatization utilizing 40 μL of acetic anhydride and 0.5% (w/v) K₂CO₃. Under the selected conditions, pre-concentration factor of 235–1174, limit of detection of 0.005–0.68 μg/L (S/N = 3) and linearity range of 0.02–300 μg/L have been obtained. A reasonable repeatability (RSD ≤ 10.4%, n = 5) with satisfactory linearity (0.9995 ≥ r² ≥ 0.9975) of results illustrated a good performance of the present method. The relative recovery of different natural water samples was higher than 84%.     

Development and validation of a multi-residue method for the determination of pesticides in honeybees using acetonitrile-based extraction and gas chromatography–tandem quadrupole mass spectrometry

An optimized analytical method employing gas chromatography–tandem quadrupole mass spectrometry (GC–MS/MS) has been developed for the simultaneous screening of roughly 150 pesticides in honeybees suspected of poisoning by pesticides during field spraying. In this work, a sample preparation approach based on acetonitrile extraction followed by dispersive solid-phase extraction (d-SPE) cleanup was implemented and validated for pesticides in honeybees for the first time. The procedure involved homogenization of a 2 g sample (23 insects on average) with acetonitrile–water mixture followed by salting out with citrate buffer, magnesium sulphate and sodium chloride. An amount of matrix constituents with limited solubility in acetonitrile was reduced in the extract by precipitation at low-temperature (freezing-out cleanup). Hereafter, d-SPE cleanup was carried out using primary secondary amine (PSA), octadecyl (C18) and graphitized carbon black (GCB). This combination of cleanup steps ensured efficient extract purification. Linearity of the calibration curves was studied using matrix-matched standards in the concentration range between 4 and 500 ng mL⁻¹ (equivalent to 10 and 1250 ng g⁻¹), and coefficients of determination (R²) were ≥0.99 for approximately 90% of the targeted compounds. The recovery data were obtained by spiking honeybees samples free of pesticides at three concentration levels of 10, 50, and 500 ng g⁻¹ (approximately 0.9, 4.3, 43.5 ng per bee). At these spiking levels 47, 77 and 92% of the targeted compounds were recovered, respectively. Generally the recoveries were in the range between 70 and 120% with precision values, expressed as relative standard deviation (RSD) ≤ 20%. The expanded uncertainty was estimated following a “top down” empirical model as being 28% on average (coverage factor k = 2, confidence level 95%). Preliminary results from practical application to analysis of real samples are presented. A total of 25 samples of honeybees from suspected pesticides poisoning incidents were analyzed, in which 10 different pesticides were determined.     

Novel derivatisation technique for the determination of chlorophenoxy acid type herbicides by gas chromatography–mass spectrometry

The analytical detection of chlorophenoxycarboxylic-acid-type herbicides (2,4-D, dichloprop, MCPA, etc.) in environmental samples is often a problem in instrumental analysis, as these compounds containing free carboxylic groups require chemical derivatisation prior to gas chromatographic (GC) methods. Nine chlorophenoxy-acid-type herbicide active ingredients have been derivatised successfully with trimethylsilyl N,N-dimethyl carbamate and t-butyldimethylsilyl N,N-dimethyl carbamate by forming their trimethylsilyl (TMS) and t-butyldimethylsilyl (TBDMS) esters, respectively. The detection and determination of the derivatives were performed by capillary gas chromatography–mass spectrometry. The study included determination of retention indices, mass spectral properties and comparison of derivatives produced. The mass spectra of TBDMS derivatives are usually dominated by very characteristic ions [M-57]⁺ resulting from the cleavage of t-butyl moiety during electron impact (EI) ionisation in the mass spectrometer. Limits of detection were 5 to 100 pg applying GC with EI-MS detection in full scan mode. The method, using SPE sample preparation, was applied for the analysis of 115 ground water and surface water samples collected in Békés County, Hungary in 2009.     

Dispersive liquid–liquid microextraction followed by gas chromatography–mass spectrometry for the rapid and sensitive determination of UV filters in environmental water samples

The performance of the dispersive liquid–liquid microextraction (DLLME) technique for the determination of eight UV filters and a structurally related personal care species, benzyl salicylate (BzS), in environmental water samples is evaluated. After extraction, analytes were determined by gas chromatography combined with mass spectrometry detection (GC-MS). Parameters potentially affecting the performance of the sample preparation method (sample pH, ionic strength, type and volume of dispersant and extractant solvents) were systematically investigated using both multi- and univariant optimization strategies. Under final working conditions, analytes were extracted from 10 mL water samples by addition of 1 mL of acetone (dispersant) containing 60 μL of chlorobenzene (extractant), without modifying either the pH or the ionic strength of the sample. Limits of quantification (LOQs) between 2 and 14 ng L⁻¹, inter-day variability (evaluated with relative standard deviations, RSDs) from 9% to 14% and good linearity up to concentrations of 10,000 ng L⁻¹ were obtained. Moreover, the efficiency of the extraction was scarcely affected by the type of water sample. With the only exception of 2-ethylhexyl-p-dimethylaminobenzoate (EHPABA), compounds were found in environmental water samples at concentrations between 6 ± 1 ng L⁻¹ and 26 ± 2 ng mL⁻¹.