Trace analysis of benzophenone-derived compounds in surface waters and sediments using solid-phase extraction and microwave-assisted extraction followed by gas chromatography–mass spectrometry

This study describes a procedure for determining eight benzophenone-derived compounds in surface waters and sediments. These include the pharmaceutical ketoprofen, its phototransformation products 3-ethylbenzophenone and 3-acetylbenzophenone, and five benzophenone-type ultraviolet (UV) filters. The proposed analytical method involves the pre-concentration of water samples by solid-phase extraction (SPE) and microwave-assisted extraction (MAE) of sediment samples followed by derivatization and analysis by gas chromatography–mass spectrometry. Different parameters were investigated to achieve optimal method performance. Recoveries of 91 to 96 % from water samples were obtained using HLB Oasis SPE cartridges, whereas MAE of sediments (30 min at 150 °C) gave recoveries of 80 to 99 %. Limits of detection were between 0.1 and 1.9 ng L^?1 for water samples and from 0.1 to 1.4 ng g^?1 for sediment samples. The developed method was applied to environmental samples and revealed the presence of UV filters in the majority of the surface waters with up to 690 ng L^?1 of 2-hydroxy-4-methoxybenzophenone. By contrast, ketoprofen (≤2,900 ng L^?1) and its degradation products (≤320 ng L^?1) were found in only two rivers, both receiving wastewater treatment plant effluents. Sediment analysis revealed benzophenone to be present in concentrations up to 650 ng g^?1, whereas concentrations of other compounds were considerably lower (≤32 ng L^?1). For the first time, quantifiable amounts of two ketoprofen transformation products in the aqueous environment are reported.     

Simultaneous derivatization and extraction of iodine from milk samples by hollow fiber liquid-phase microextraction followed by gas chromatography-electron capture detection

A simple, low-cost and sensitive method is demonstrated for derivatization and extraction of iodine from milk samples using hollow fiber liquid-phase microextraction (HF-LPME) and gas chromatography-electron capture detection. Iodide ions are converted to iodine under acidic medium and in the presence of an oxidant. The generated iodine reacted with 3-pentanone in extraction vial to give 2-iodo-3-pentanone and was extracted into 4 μL of 1-octanol located in the lumen of a hollow fiber. Organic solvent was selected using one variable at a time optimization method and the other main factors affecting derivatization and HF-LPME procedures were evaluated using a Taguchi’s L₁₆ (4⁵) orthogonal array. Under optimal conditions, the method showed low limit of detection (0.5 ng mL^?1), wide linear range (1–2,000 ng mL^?1) with good correlation coefficient (0.9997) and acceptable relative standard deviation (4.6 %, n = 5). Finally, the developed method was successfully applied for determination of iodide in real samples including infant milk formulas and cow milk with reasonable relative recoveries (99.8–110.5 %).     

Magnetic titanium oxide nanoparticles for hemimicelle extraction and HPLC determination of organophosphorus pesticides in environmental water

We report on a method for the extraction of organophosphorus pesticides (OPPs) from water samples using mixed hemimicelles and magnetic titanium dioxide nanoparticles (Fe₃O₄@TiO₂) modified by cetyltrimethylammonium. Fe₃O₄@TiO₂ nanoparticles were synthesized by a hydrothermal process and then characterized by scanning electron microscopy and Fourier transform IR spectrometry. The effects of the quantity of surfactant, extraction time, desorption solvent, pH value, extraction volume and reuse of the sorbent were optimized with respect to the extraction of OPPs including chlorpyrifos, dimethoate, and trichlorfon. The extraction method was applied to analyze OPPs in environmental water using HPLC along with UV detection. The method has a wide linear range (100–15,000 ng L^?1), good linearity (r?>?0.999), and low detection limits (26–30 ng L^?1). The enrichment factor is ~1,000. The recoveries (at spiked levels of 100, 1,000 and 10,000 ng L^?1) are in the range of 88.5–96.7 %, and the relative standard deviations range from 2.4 % to 8.7 %.

Cooling-Assisted Headspace Hollow Fiber-Based Liquid-Phase Microextraction Setup for Direct Determination of PAHs in Solid Samples by Using Volatile Solvents

To reinforce the extraction efficiency of the liquid- and solid-phase microextraction methods, different cooling-assisted setups have been employed, most of which are complicated, expensive, tedious, and do not show good performances due to indirect transfer of cold to the extraction phase. In this research, a simple, low-cost and effective cooling-assisted headspace hollow fiber-based liquid-phase microextraction (CA-HS-HF-LPME) device was fabricated and evaluated, which is able to directly cool down the extraction phase in different modes of LPME. It was coupled to GC-FID and utilized for the direct determination of PAHs in contaminated soil samples using volatile organic solvents. Different effective experimental variables including type and volume of extraction solvent, extraction time and temperature, and temperature of the cooled organic solvent were evaluated and optimized. Under the optimized experimental conditions (e.g., organic extracting solvent: 3 µL of acetone; extraction time: 20 min; extraction temperature: 90 °C; and temperature of cooled organic drop: −25 °C), good linearity of calibration curves (R ² > 0.99) was obtained in a concentration range of 1–10,000 ng g⁻¹. The limits of detection (LODs) were obtained over the range of 0.01–0.1 ng g⁻¹. The relative standard deviations (RSD%, n = 6) of 0.1 µg g⁻¹ PAHs were found to be 4.7–10.1 %. The CA-HS-HF-LPME-GC-FID method was successfully used for the direct determination of PAHs in contaminated soil and plant samples, with no sample manipulation. The results were in agreement with those obtained by a validated ultrasound-assisted solvent extraction (UA-SE) method.

     

Determination of ultra traces of lead in water samples after combined solid-phase extraction–dispersive liquid–liquid microextraction by graphite furnace atomic absorption spectrometry

A solid-phase extraction coupled with dispersive liquid–liquid microextraction (DLLME) method followed by graphite furnace atomic absorption spectrometry (GFAAS) was developed for the extraction, preconcentration, and determination of ultra trace amounts of lead in water samples. Variables affecting the performance of both steps were thoroughly investigated. Under optimized conditions, 100 mL of lead solution were first concentrated using a solid phase sorbent. The extracts were collected in 1.50 mL of THF and 18 μL of carbon tetrachloride was dissolved in the collecting solvent. Then 5.0 mL pure water was injected rapidly into the mixture of THF and carbon tetrachloride for DLLME, followed by GFAAS determination of lead. The analytical figures of merit of method developed were determined. With an enrichment factor of 1,800, a linear calibration of 3–60 ng L^?1 and a limit of detection of 1.0 ng L^?1 were obtained. The relative standard deviation for seven replicate measurements of 30 ng L^?1 of lead was 5.2 %. The relative recoveries of lead in mineral, tap, well, and river water samples at spiking level of 10 and 20 ng L^?1 are in the range 94–106 %.     

Determination of methyl mercury in water samples with electromagnetic induction thermal desorption/pyrolysis coupled to atomic fluorescence spectrometry

A novel non-chromatographic method for the pre-concentration and determination of trace methyl mercury in water samples has been proposed. This method included two main steps: (1) The methyl mercury in sample solution was adsorbed on PDMS of the Fe/SiO₂/PDMS bed enrichment column; (2) the analyte was thermally desorbed from the enrichment column and pyrolysed to Hg⁰ in an iron particle bed pyrolysis column by using electromagnetic induction heating technique, and then detected by an on-line coupled atomic fluorescence detector. Several factors affecting the enrichment column preparation and concentration procedure have been investigated and optimised. Under optimal condition, the detection limit (3σ) was 0.2 ng L^–1, along with relative standard deviations of 2.4% (10 ng L^–1, N = 11) for the repeatability study. The enrichment factor obtained was 108. The two standard reference materials (GBW08675, GBW10029) were analysed to validate the present method. This method was successfully applied to the determination of ng L^–1 methyl mercury in water samples.     

Analysis of PAHs in Water and Fruit Juice Samples by DLLME Combined with LC-Fluorescence Detection

A simple, rapid and efficient method termed dispersive liquid–liquid microextraction combined with liquid chromatography-fluorescence detection, has been developed for the extraction and determination of polycyclic aromatic hydrocarbons (PAHs) in water and fruit juice samples. Parameters such as the kind and volume of extraction solvent and dispersive solvent, extraction time and salt effect were optimized. Under optimum conditions, the enrichment factors ranged from 296 to 462. The linear range was 0.01–100 μg L^?1 and limits of detection were 0.001–0.01 μg L^?1. The relative standard deviations (RSDs, for 5 μg L^?1 of PAHs) varied from 1.0 to 11.5% (n = 3). The relative recoveries of PAHs from tap, river, well and sea water samples at spiking level of 5 μg L^?1 were 82.6–117.1, 74.9–113.9, 77.0–122.4 and 86.1–119.3%, respectively. The relative recoveries of PAHs from grape and apple juice samples at spiking levels of 2.5 and 5 μg L^?1 were 80.8–114.7 and 88.9–123.0%, respectively. It is concluded that the proposed method can be successfully applied for determination of PAHs in water and fruit juice samples.     

Analysis of Six Phenolic Endocrine Disrupting Chemicals in Surface Water and Sediment

An efficient and reliable method based on gas chromatography–mass spectrometry (GC–MS) was developed for the extraction and analysis of six phenolic endocrine disrupting chemicals (EDCs), such as 4-nonylphenol (4-NP), nonylphenol-mono-ethoxylate (NP1EO), nonylphenol-di-ethoxylate (NP2EO), 4-tert-octylphenol (4-t-OP), bisphenol A (BPA) and 4-cumylphenol (4-CP) in surface water and sediment. The method was developed by using microwave-assisted extraction (MAE), solid phase extraction (SPE) and derivatization procedure. The MAE procedures were performed by optimizing three key process factors, consisted of extraction solvent, extraction temperature and holding time, affecting the extraction efficiency from sediment samples. For SPE, various parameters that may affect the recovery efficiency of water samples, such as SPE phase cartridge, elution solvent, as well as pH of water samples, were investigated. A series of derivatization conditions, such as derivatization reagent, reaction temperature and reaction time, were improved. The method achieved good repeatability and reproducibility with relative standard deviations <13% for all target EDCs in the both samples. Satisfactory recoveries for spiked water and sediment samples ranged from 85 to 101% and 74 to 105%, respectively. The limits of quantification varied from 0.20 (4-t-OP) to 11.50 ng L^?1 (NP2EO) and from 0.31 (4-t-OP) to 9.50 ng g^?1 dry weight (dw) (NP2EO) for water samples and sediment samples, respectively. The established method was successfully applied to the analysis of target EDCs in surface water and sediment samples collected from Caohai site of Dianchi Lake, China. The results showed that NP1EO, NP2EO and BPA were the three dominant phenolic EDCs in the site, reaching 114, 97 and 149 ng L^?1 in surface water, while 444, 186 and 178 ng g^?1 dw in surface sediment, respectively.     

Dispersive liquid–liquid microextraction combined with flow injection inductively coupled plasma mass spectrometry for simultaneous determination of cadmium, lead and bismuth in water samples

Dispersive liquid–liquid microextraction (DLLME) was combined with flow injection inductively coupled plasma mass spectrometry for simultaneous determination of cadmium, lead and bismuth in water samples. The metal elements were complexed with sodium diethyldithiocarbamate, and then the complexes were extracted into carbon tetrachloride by using DLLME. Under the optimized conditions, the enrichment factors for Cd, Pb and Bi are 460, 900 and 645 in 5 mL of a spiked water sample, respectively. The calibration graphs for the three metals are linear in the range of concentrations from <10 ng L^?1 to 1,000 ng L^?1. The detection limits are 0.5 ng L^?1, 1.6 ng L^?1 and 4.7 ng L^?1, respectively. The relative standard deviations for ten replicate measurements of 50 ng L^?1 cadmium, lead and bismuth are 2.6%, 6.7%, and 4.9%, respectively, and the relative recoveries in various water samples at a spiking level of 50 ng L^?1 range from 83.6% to 107.0%.     

Occurrence of cytostatic compounds in hospital effluents and wastewaters,determined by liquid chromatography coupled to high-resolution mass spectrometry

The occurrence of 26 commonly used cytostatic compounds in wastewaters was evaluated using an automated solid-phase extraction (SPE) method with liquid chromatography–high-resolution mass spectrometry (LC–HRMS). Detection was optimized using Oasis HLB SPE cartridges at pH 2. Two hospital effluents and their two receiving wastewater treatment plants were sampled over five days. In hospital effluents, eight cytostatics were detected at levels up to 86.2 μg L^?1 for ifosfamide, 4.72 μg L^?1 for cyclophosphamide, and 0.73 μg L^?1 for irinotecan, the three most relevant compounds identified. Cyclophosphamide and megestrol acetate were found in wastewaters at concentrations up to 0.22 μg L^?1 for the latter. The predicted environmental concentrations (PEC) in sewage effluents of ifosfamide (2.4–4.3 ng L^?1), capecitabine (11.5–14.2 ng L^?1), and irinotecan (0.4–0.6 ng L^?1), calculated from consumption data in each hospital, published excretion values for the target compounds, and wastewater elimination rates, were in agreement with experimental values.     

Comparison of Modifiers for Mercury Speciation in Water by Solid Phase Extraction and High Performance Liquid Chromatography–Atomic Fluorescence Spectrometry

Diethyldithiocarbamate and 2-mercaptoethanol modifiers were compared for the preconcentration of mercury species in water by C₁₈ solid phase extraction (SPE). The recovery values of mercury species were determined by high performance liquid chromatography–atomic fluorescence spectrometry. The eluent type, pH, chloride ion concentration, humic acid concentration, and storage time were evaluated to compare the preconcentration efficiency. L-cysteine was employed to elute the mercury compounds. Less eluent was needed for 2-mercaptoethanol modified SPE than for diethyldithiocarbamate modified SPE at an L-cysteine concentration of 0.12%. Diethyldithiocarbamate modified SPE could be used over a wider pH range and higher humic acid concentrations, whereas 2-mercaptoethanol modified SPE was less affected by the chloride concentration. Both modified SPE systems stored mercury species for 5 days, but diethyldithiocarbamate modified SPE could be stored longer. Diethyldithiocarbamate SPE provided limits of detections of 3.5, 2.5, and 4 ng · L^?1 and average recoveries of 90.78 ± 3.37%, 96.79 ± 5.12%, and 84.88 ± 5.37% for mercury(II), methylmercury, and ethylmercury, respectively. The relative standard deviation was less 6.5%. For 2-mercaptoethanol modified SPE, the limits of detection were 1.4, 1, and 1.6 ng · L^?1 and the recoveries were of 87.66 ± 8.45%, 86.70 ± 2.61%, and 91.31 ± 6.98% for mercury(II), methylmercury, and ethylmercury, respectively, with a relative standard deviation below 9.7%. Water should be characterized for its physical and chemical characteristics before mercury preconcentration to choose the most suitable method.     

Polythiophene–Chitosan Magnetic Nanocomposite as a Novel Sorbent for Disperse Magnetic Solid Phase Extraction of Triazine Herbicides in Aquatic Media

In this paper, polythiophene/chitosan magnetic nanocomposite as a novel adsorbent is proposed for the preconcentration of triazines in aqueous samples prior to gas chromatography. The synthesized nanoparticles, magnetic chitosan and polythiophene–chitosan magnetic nanocomposite were characterized by scanning electron microscopy. The magnetic polythiophene–chitosan nanocomposite containing analytes could be removed from the sample solution by applying a permanent magnet. The major factors influencing the extraction efficiency including desorption conditions, nanocomposite components ratio, sorbent amount, extraction time, ionic strength and sample pH were optimized. The developed method proved to be rather convenient and offers sufficient sensitivity and good reproducibility. The limit of detection (S/N = 3) and limit of quantification (S/N = 10) of the method under optimized conditions were 10–30 and 100 ng L⁻¹, respectively. Under the optimum conditions, good linearity was obtained within the range of 100–5000 ng L⁻¹ for all triazines with correlation coefficients >0.9994. The relative standard deviation at a concentration level of 150 ng L⁻¹ was 7–12 %. Furthermore, the method was successfully applied to the determination of triazines in real samples, where relative recovery percentages of 96–102 % were obtained. Compared with other methods, the current method is characterized by easy, fast separation and low detection limits.

     

Feasibility of hydrofluoric acid etched sand particles for enrichment and determination of polychlorinated biphenyls at trace levels in environmental water samples

This study aims to investigate the feasibility of etched sand particles being used as solid-phase extraction adsorbents to enrich polychlorinated biphenyls (PCBs), which are typical persistent organic pollutants in the environment, at trace levels. Gas chromatography–tandem mass spectrometry was selected to detect the compounds. Etched sand particles exhibited excellent merits on the enrichment of PCBs. Related important factors affecting extraction efficiencies were investigated and optimized in detail. Under optimized conditions, low limits of detection (0.42 to 3.69 ng L^?1), wide linear range (10 to 1,000 ng L^?1), and high repeatability (1.9 to 8.2 %) were achieved. The developed method was validated with several real water samples, and satisfactory results were obtained. All of these findings indicate that etched sand particles would be useful for the enrichment and determination of organic pollutants at trace levels in water samples.     

Multivariate optimization of the hollow fiber-based liquid phase microextraction of lead in human blood and urine samples using graphite furnace atomic absorption spectrometry

The present study developed a liquid-phase microextraction based on hollow fiber coupled with graphite furnace atomic absorption spectrometry for the effective extraction and quantitation of lead from urine and blood samples. A multivariate design was used for the optimization of the experimental conditions to ensure high extraction efficiency. Six factors (solvent type, chelating agent, time extraction, temperature, donor phase pH, and acceptor phase pH) were obtained by screening eleven factors of the Plackett–Burman design; these were optimized using the central composite design of response surface methodology. The optimum conditions of donor phase pH, acceptor phase pH, temperature, and extraction time were 5, 9.5, 40 °C, and 120 min, respectively. In addition, oleic acid containing dicyclohexyl-18-krone-6 was used for the membrane phase. Under optimal conditions, the enrichment factor, limit of detection, and limit of quantification were obtained in the ranges of 21.3–18.7, 0.001–0.002 ng mL^?1, and 0.008–0.01 ng mL^?1, respectively, in urine and blood samples. The linearity of the calibration curve was established for the concentration of Pb in the range of 1–50 ng mL^?1 (r²?=?0.9983). Finally, the performance of the developed method was evaluated for the determination of lead in urine and blood samples, and satisfactory results were obtained (RSDs <?10% with recovery >?95).     

Determination of Atmospheric Polycyclic Aromatic Hydrocarbons Using Accelerated Solvent Extraction

Abstract

An accelerated solvent extraction (ASE) method has been developed for the determination of polycyclic aromatic hydrocarbons (PAHs) present in both atmospheric particulate and gaseous phases in this study. Extraction parameters such as the combination of solvents, extraction temperature, and static extraction time were investigated and optimized. Effective extraction was achieved using a 3:1 mixture of n-hexane and acetone as extraction solvents at 100°C in 30 min for all the compounds studied. The optimized extraction method was compared with conventional extraction methods and validated using National Institute of Standards and Technology (NIST)–certified standard reference material (SRM) 1649a. The recoveries obtained for certified 12 PAHs were in the range of 82–126% with relative standard deviation (RSD) between 6 and 28%. The validated ASE technique was used followed by gas chromatography–mass spectrometry (GC-MS) for the determination of PAHs distributed between gaseous and particulate phases in the atmosphere of Singapore. Total average concentrations of PAHs in air samples were 33.54 ± 19.32 ng m^?3, with 4.72 ± 2.80 ng m^?3 in particulate phase and 28.82 ± 16.92 ng m^?3 in gaseous phase, respectively. The results obtained from this study are compared to those reported from other areas of the world.     

Improvements in analytical methodology for the determination of frequently consumed illicit drugs in urban wastewater

Rapid and sensitive analytical methodology based on ultra high-performance liquid chromatography-tandem mass spectrometry has been developed for the determination of widely consumed drugs of abuse (amphetamines, MDMA, cocaine, opioids, cannabis and ketamine) and their major metabolites in urban wastewaters. Sample clean-up and pre-concentration was performed by a generic off-line SPE procedure using Oasis HLB. Special effort was made to incorporate amphetamine, which was found highly problematic in the wastewater samples tested, including an additional clean-up with Oasis MCX SPE and dispersive primary secondary amine. Correction for possible SPE losses or degradation during storage was made by the use of isotope-labelled internal standards (ILIS), available for all compounds, which were added to the samples as surrogates. Although ILIS were also efficient for matrix effects correction, the strong ionization suppression observed was not eliminated; therefore, a four-fold dilution prior to SPE was applied to influent wastewaters and a low injection volume was selected (3 μL), in order to reach a compromise between matrix effects, chromatographic performance and sensitivity. The method was validated at 25 and 200 ng L^?1 (effluent), and 100 and 800 ng L^?1 (influent), obtaining limits of quantification (i.e. the lowest level that the compound can be quantified and also confirmed with at least two MS/MS transitions) between 0.4–25 ng L^?1 (effluent) and 2–100 ng L^?1 (influent). The applicability of the method was demonstrated by analysis of 14 influent and 14 effluent wastewater samples collected over 2 weeks in Castellón (Spain) within a European collaborative study.     

PAH and PCB determination of the concentration gradient in moss Pleurozium schreberi near a highway,and seasonal variability at the background reference site

Moss (Pleurozium schreberi) was investigated as biomonitor of atmospheric polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs). Samples were collected at a distance of 10, 50 and 100 m from a highway and were seasonally collected in a forest stand near a regional background air pollution station situated approximately 30 km from the highway. The samples from the background area were dried using two different techniques in parallel, air-drying and freeze-drying. Simultaneous pressurised liquid extraction of PAHs and PCBs was performed, followed by purification using gel permeation chromatography of the crude extract. The concentration of the 15 most important Environmental Protection Agency (EPA) PAHs was determined by gas chromatography coupled with ion-trap mass spectrometry with a selected ion storage acquisition programme, and the PCB concentrations were determined using a mass spectrometer operated in tandem mass spectrometry (MS/MS) mode. Acceptable recoveries and quality parameters for PAHs and PCBs were achieved with the use of pressurised liquid extraction followed by gel permeation chromatography. The detection limit was <0.76 ng g^?1 for PAHs and <0.04 ng g^?1 for PCBs. Possible contamination of the moss samples by 3-ring PAHs and PCBs in the atmosphere was found during air drying. Increased PAH and PCB concentrations caused by car engine exhausts and by asphalt and oil evaporation were found near the highway. Generally, the PAH and PCB concentrations in moss decreased exponentially with distance from the highway. The organic compound concentrations close to the background station showed seasonal fluctuations corresponding to the fluctuations in the local air temperature and particle concentration.     

Quantification of Thiram in Honeybees: Development of a Chemiluminescent ELISA

Abstract

A Chemiluminescence Enzyme‐Linked Immuno‐Sorbent Assay (CL‐ELISA) for determination and quantification of the fungicide thiram in honeybees was developed in an indirect competitive format. The assay was optimized by determining: the optimal coating conjugate concentration and anti‐thiram antiserum dilution, the effect of the incubation time on the competitive step, the tolerance to organic solvents. The IC₅₀ and the limit of detection (LOD) values were 60 ng mL^?1 and 9 ng mL^?1, respectively, similar to those of colorimetric ELISA with a calibration range of 9–15,000 ng mL^?1. Cross reactivity of some related compounds such as some dithiocarbamates, a thiocarbamate, the ethylenethiourea and the tetramethylthiourea were tested. The assay was then applied to honeybees sample extracts obtained by using the liquid‐liquid extraction or the graphitized carbon‐based solid phase extraction.

The calibration curves in honeybee extracts from liquid‐liquid procedure gave an IC₅₀ of 141 ng mL^?1 and a LOD of 17 ng mL^?1. In case of extracts obtained by SPE these values were 139 ng mL^?1 and 15 ng mL^?1, respectively. The average recovery value from honeybee extracts spiked with 75 ng mL^?1 of thiram was 72% for SPE, higher than for liquid‐liquid extraction (60%). On the opposite, when the honeybees were directly spiked with 2 and 10 ppm the average recovery was higher for liquid‐liquid extraction (54%), than for SPE (31%). Finally, the assay was applied to honeybee samples collected during monitoring activities in Italy and Russia.     

Multiwalled Carbon Nanotubes as SPE Adsorbents for Simultaneous Determination of Seven Sulfonylurea Herbicides in Environmental Water by LC–MS–MS

An effective and rapid method was developed for simultaneous determination of seven sulfonylurea herbicides in environmental water using multiwalled carbon nanotubes as solid-phase extraction sorbent coupled with liquid chromatography–tandem mass spectrometry. Important parameters influencing the extraction efficiency such as pH of the sample solution, flow rate of sample loading, the eluent and its volume were optimized. Under optimum conditions, good linearity was obtained for all herbicides (r ² > 0.99) over the range of 0.05–5,000 ng L^?1, and precisions (RSD) for nine replicate measurements of a standard mixture of 200 ng L^?1 were 1.9–7.4%. The limits of detection and quantification were 0.01–0.20 and 0.05–1.00 ng L^?1, respectively. The proposed method was successfully applied to the analysis of tap water, spring water, ground water and well water, and mean recoveries for seven analytes at three spiked concentration levels were from 81.5 to 110.5% with RSDs between 0.3 and 7.0%. The results showed that the established method has wide application to analyze sulfonylurea herbicides at trace level in water.     

QuEChERS and solid phase extraction methods for the determination of energy crop pesticides in soil,plant and runoff water matrices

QuEChERS and solid phase extraction (SPE) methods were applied for determining four herbicides (metazachlor, oxyfluorfen, quizalofop-p-ethyl, quinmerac) and one insecticide (α(±)-cypermethrin) in runoff water, soil, sunflower and oilseed rape plant matrices. Determination was performed using gas chromatography mass spectrometry (GC-MS), whereas high-pressure liquid chromatography mass spectrometry (HPLC-MS) was used for quinmerac. In all substrates linearity was evaluated using matrix-matched calibration samples at five concentration levels (50–1000 ng L^?1 for water, 5–500 μg kg^?1 for soil and 2.5–500 μg kg^?1 for sunflower or oilseed rape plant). Correlation coefficient was higher than 0.992 for all pesticides in all substrates. Acceptable mean recovery values were obtained for all pesticides in water (65.4–108.8%), soil (70.0–110.0%) and plant (66.1–118.6%), with intra- and inter-day RSD% below 20%. LODs were in the range of 0.250–26.6 ng L^?1 for water, 0.10–1.8 μg kg^?1 for soil and 0.15–2.0 μg kg^?1 for plants. The methods can be efficiently applied for field dissipation studies of the pesticides in energy crop cultivations.