Analysis Of Multi-class Pesticides Research Articles

Ultrasonic-induced grafted lanthanum sulfide decorated multi-walled carbon nanotube onto bacterial cellulose applied for adsorption of pesticides in environmental waters

A new biosorbent was fabricated by modification of bacterial cellulose biopolymer grafted with lanthanum sulfide decorated carboxylated multiwall carbon nanotube (La2S3@MWCNT@BC). The sorbent was employed in a green alternative dispersive-solid phase extraction of a variety of 14 pesticides in environmental water samples. The analyses were performed using GC-µECD. The properties and structure of La2S3@MWCNT@BC nanocomposite were characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, and adsorption-desorption isotherms. The composition of the sorbent was also investigated to evaluate the adsorptive properties of its constituents. The impact of various parameters influencing extraction efficacies such as sorbent dose, adsorption time, sample pH, ionic strength, and desorption conditions was investigated. The method was validated by specificity, matrix effect % (-0.4 to -7.4), enrichment factor (4–10), limits of quantification (0.007–0.31 μg L−1), matrix-matched calibration linearity (0.01–200 µg L−1), determination coefficients (r2=0.9921–0.9998), and precision. The optimized method was applied for the analysis of multiclass pesticides in seven environmental and drinking waters and the recoveries were obtained in the 81–108 % range with RSDs of 2.5–4.7 %. This paper is the first report on the synthesis and use of La2S3@MWCNT@BC nanocomposite to extract pesticides from different water samples. The greenness of the procedure was evaluated by the AGREE protocols.

Method Development and Validation in Water Matrix Employing Tandem Mass Spectrometry: Quantitative Analysis of 76 Multiclass Pesticides in Groundwater Samples Collected from Delhi Ncr Region by Quechers Based Liquid-liquid Extraction Method

A miniaturized, QuEChERS based, liquid–liquid extraction method followed by tandem gas chromatography–mass spectrometry determination was developed and validated for 76 pesticide residues determination in water using European SANTE/11312/2021 guideline and monitored the 70 ground water samples collected from Delhi NCR, India region for the determination of pesticide residues. The accuracy, precision, specificity, linearity, recovery, repeatability, reproducibility, robustness, limit of detection and limit of quantification of the method were evaluated. Uncertainty measurement was calculated for each analyte. The samples were extracted with dichloromethane using liquid-liquid extraction process. Each Pesticide was optimized in terms of different MS parameters and chromatographic conditions by GC-MS/MS using Multiple Reaction Monitoring (MRM) mode. In linearity regression co-efficient (R2) value of each pesticide was determined in the range of 0.9856-0.9997. The percent average recoveries were found from 87.98—119.99 at 1, 5 and 10 LOQ spiking level. The method performance complied with the regulatory requirements, and thus, can be implemented. LOD and LOQ of the pesticides were found 10µg/L and 30µg/L respectively. Expanded Measurement of uncertainty of all pesticides was below ±50 percent of mean recovery value as per SANTE 11312/2021. Organophosphorous, fungicides, and pyrethroids were the group of pesticides most frequently found. In this study, 12 pesticides were found above the MRL (EEC Council Directive 1980/778/EEC). Additionally, dieldrin, which is now banned by law in India, was found in samples of ground water. The method provided a high throughput analysis of multi-class pesticides with satisfactory selectivity, sensitivity, accuracy, and precision.

Multiresidue analysis of pesticides in three Indian soils: method development and validation using gas chromatography tandem mass spectrometry

The paper reports a multiresidue method that was validated on 220 multi-class pesticides in three major Indian soils, namely, (i) new alluvial soil (NAS); (ii) red lateritic soil (RS) and (iii) black soil (BS) from three different regions. An ethyl acetate-based extraction method with a freezing-out cleanup step was employed for sample preparation, followed by gas chromatography-tandem mass spectrometric analysis. The method that was initially optimized on BS worked satisfactorily for the other two soil matrices. At the spiking level of 10 µg/kg (LOQ), the recoveries were satisfactory (within 70–120%) with precision-RSDs, ≤20% (n = 6) for 85, 88.6, and 89% of compounds in BS, RS, and NAS respectively. At 20 µg/kg, the method performance was satisfactory in each soil for all pesticides. When this validated method was applied to analyse 25 field samples, 6 pesticides were detected in them. In each case, precision (RSD) was <20%. The method sensitivity, accuracy and precision complied with the SANTE/2020/12830 guidelines. The method can be applied for environmental monitoring and risk assessment purposes, thus aiding in regulating pesticide usage in agricultural fields. The limitations and future scope of the study are also discussed. Highlights A multiresidue method is reported for simultaneous analysis of multi-class pesticides in diverse soils The method was validated on 220 pesticides in new alluvial, red lateritic and black soils Sample preparation involved extraction with ethyl acetate and cleanup by a freezing step The residues were estimated by gas chromatography tandem mass spectrometry (GC-MS/MS) The method accuracy and precision complied with the EU’s SANTE guidelines

Copolymerized Natural Deep Eutectic Solvent Encapsulated in Calcium Alginate Beads: Application as a Green Sorbent for Analysis of Multiclass Pesticides in Nonalcoholic Malt Beverages by GC–MS/SIM

A novel sorbent material consisting of a copolymeric deep eutectic solvent (DES) gel doped in calcium alginate (CA) hydrogel beads was synthesized and used in a green micro-solid phase extraction of 24 pesticides in 8 nonalcoholic malt beverages. The analyses were performed by gas chromatography–mass spectrometry/selective-ion monitoring. The DES was prepared by combining thymol (Thy, thyme oil) and methacrylic acid (MAA, can be obtained from Roman chamomile oil) in a 1:1 molar ratio via the heating-stirring method. Then, it was copolymerized using ammonium persulfate as a polymerization initiator and ethylene glycol dimethacrylate (EGDMA) as a crosslinking monomer through thermally induced free-radical reaction and finally was encapsulated in CA beads. The DES was characterized by Fourier transform infrared, Fourier transform nuclear magnetic resonance, and scanning electron microscopy techniques. A comparison study indicated that t extractionhe efficiency of the modified CA with polymeric DES (CA/[poly(MAA-co-EGDMA)]:[Thy]) was 1.5–3.4-fold higher than unmodified CA hydrogel beads. The influence of significant parameters affecting extraction efficiency was optimized. The method was validated by the matrix effect, specificity, precision, limits of quantifications (0.010–0.230 μg L–1), matrix-matched calibration linearity (0.010–300 μg L–1), and determination coefficients (r2 = 0.990–0.998). The method was successfully utilized for the detection of pesticide residues in nonalcoholic malt beverage samples, and the obtained relative recoveries were 68.2–115.6% (relative standard deviation < 10.2%). The procedure’s greenness was evaluated by the Complex Green Analytical Procedure Index and the Analytical Eco-Scale protocols. This paper is the first report on the preparation and utilization of this novel sorbent for the analysis of pesticides in nonalcoholic malt drinks.

Development of a sustainable dispersive liquid–liquid microextraction based on novel hydrophobic and hydrophilic natural deep eutectic solvents for the analysis of multiclass pesticides in water

A novel green dispersive liquid–liquid microextraction (DLLME) technique based on two new natural deep eutectic solvents (NaDESs) was developed and applied to the extraction of multiclass pesticides in different environmental waters. A hydrophobic NaDES based on monoterpene thymol and myristyl alcohol was prepared in 2:1 M ratio and used as an extraction phase. Additionally, a ternary hydrophilic NaDES composed of alanine, kojic acid, and water in a 1:2:5 M ratio was prepared and applied as disperser solvent. The NaDESs were characterized by ATR-FTIR spectroscopy, NMR spectroscopy, and octanol–water partition coefficient (Kow). The analyses were performed by GC-µECD. The effect of significant parameters influencing extraction efficiency was investigated through a one-at-a-times strategy. The optimized method was validated by matrix-matched calibration, repeatability, and recovery. The method was linear in the concentration ranges of 0.003–100 μg L−1 for 14 pesticides and 0.013–50 μg L−1 for two pesticides with the determination coefficients > 0.9712. The accuracy was assessed by recovery evaluation at the spike levels of 10 and 20 µg/L, in the range of 63.7–104.5%, with RSD ≤ 9.7%. The method was applied to the analysis of five environmental water samples, and various pesticide residues were detected in river water and groundwater samples in the concentrations range of 0.36–1.10 μg L−1. The greenness of the procedure was assessed using the Analytical Eco-Scale. This paper represents the first application of these novel natural deep eutectic solvents in DLLME and, also the first time, for the analysis of multiclass pesticides in water samples.

One-step integrated sample pretreatment technique by gas-liquid microextraction (GLME) to determine multi-class pesticide residues in plant-derived foods

Gas-liquid microextraction technique (GLME) has been integrated with dispersive solid phase extraction to establish a one-step sample pretreatment approach for rapid analysis of multi-class pesticides in different plant-derived foods. A 50 μL of organic solvent plus 40 mg of PSA were required throughout the 5-minute pretreatment procedure. Good trueness (recoveries of 67.2 – 105.4%) and precision (RSD ≤ 18.9%) were demonstrated by the one-step GLME method, with MLOQs ranged from 0.001 to 0.011 mg kg−1. As high as 93.6% pesticides experienced low matrix effect through this method, and the overall matrix effects (ME%) were generally better or comparable to QuEChERS. This method successfully quantified 2-phenylphenol, quintozene, bifenthrin and permethrin in the range of 0.001 – 0.008 mg kg−1 in real food samples. The multiresidue analysis feature of GLME has been validated, which displays further potential for on-site determination of organic pollutants in order to safeguard food safety and human health.

Development and validation of an analytical method for the multiresidue analysis of pesticides in sesame seeds using liquid- and gas chromatography with tandem mass spectrometry

For the first time, an analytical method for the multiresidue analysis of multiclass pesticides in sesame seeds using liquid- and gas chromatography with tandem mass spectrometry (LC-MS/MS and GC-MS/MS) was developed and validated. At first, the sample was comminuted after adding water (1:2 w/v). The sample preparation workflow included acetonitrile extraction, followed by freeze-out of the extract at -80°C with a subsequent cleanup by dispersive solid phase extraction (dSPE) (100 mg of C18 + 150 mg of MgSO4 for LC-MS/MS and 100 mg of C18 + 25 mg florisil + 150 mg of MgSO4 for GC-MS/MS). As noted, these cleanup steps were quite effective in removing the fatty co-extractives. The optimised sample preparation method effectively minimised the matrix effects and offered a limit of quantification (LOQ) of 0.01 mg/kg for most compounds. The LC-MS/MS and GC-MS/MS methods were validated at three levels (0.01, 0.02 and 0.05 mg/kg) for 222 and 220 compounds respectively. The method accuracy and precision complied with the performance criteria of the SANTE/12682/2019 analytical quality control procedure. The results of the intra-laboratory (involving six analysts) and inter-laboratory studies (involving eight accredited laboratories) were comparable for all pesticides. Considering its performance efficiency and alignment with the regulatory guidelines, this method can be implemented across the food testing laboratories for the monitoring of pesticide residues in sesame seeds.

Multi-class pesticide analysis in cannabis oil using coated blade spray and solid-phase microextraction with liquid chromatography coupled to mass spectrometry

The application of solid-phase microextraction (SPME) coupled to mass spectrometry to provide a high-throughput and cost-effective solution to multi-residue analysis of pesticides in cannabis oil samples has not been extensively explored. In this work, the method development steps for the extraction of an initial target list of 74 pesticides from cannabis oil via SPME for analysis with both LC-MS/MS and coated blade spray (CBS) are presented. The exploration of a washing step to remove adhered oil whilst minimally desorbing extracted analytes along with the implementation of central composited design investigation to examine compound extraction kinetics in the non-polar matrix yielded a workflow that was validated via both instrumental techniques. Of the initial target list, 37 pesticides were found to be suitable for screening or quantitation via CBS with performance validated via LC-MS/MS. The majority of compounds were found to meet the EU SANTE guidelines for analysis (i.e. linearity, precision, accuracy) whilst reaching limits of quantitation below or at Health Canada minimum regulatory limits (majority at 10 ng/mL). Examination of factors contributing to poor quantitation of pesticides via CBS are shared and explored, such as contributing isobaric interference sourced from plant byproducts and carrier oil, and comparison of signal-to-noise values achieved in cannabis oil when compared to the cannabis-free medium-chain triglyceride oil used as a carrier oil to stress the importance of matrix-match method development.

Single-Laboratory Validation of a Multi-residue Method for Simultaneous Analysis of Multi-class Pesticides in Turmeric by Liquid Chromatography Tandem Mass Spectrometry.

For years, turmeric has been used in several cuisines worldwide because of its proven health benefits. However, as its cultivation often involves applications of polar and semi-polar pesticides, their residues might cause health hazards to consumers. The dearth of a validated LC-MS/MS method for the residue analysis of these pesticides in turmeric has warranted the present study. The aim was to develop and validate a multi-residue method for simultaneous determination of multi-class pesticides in turmeric (both rhizome and powder) by LC-MS/MS. Both the rhizome and powder samples (1 kg) were soaked in water for 30 min, followed by homogenization. Each homogenate (2 g) was mixed with 10 mL water, and extracted with acetonitrile (10 mL) in the presence of acetic acid and NaCl. The extract was cleaned by using dispersive solid phase extraction (dSPE) with graphitized carbon (5 mg/mL) sorbent. The cleaned extract was measured by LC-MS/MS with a runtime of 20 min. The method was validated on 211 multi-class pesticides. The method performance was satisfactory at 10 ng/g and higher levels, in compliance with the SANTE/12682/2019 guidelines. The dSPE cleanup was effective in minimizing the matrix effects. The use of matrix-matched calibrations specific for turmeric powder and rhizome corrected all recoveries within the satisfactory range of 70-120%. The precision -RSDs were <20% for all test pesticides. The Horwitz ratio and measurement uncertainty results were satisfactory as well. As the method was convenient, selective, accurate, and repeatable, it is recommended for regulatory and commercial testing purposes. For the first time, this study reports a validated LC-MS/MS method for the multi-residue analysis of pesticides in turmeric. The method provided a high throughput analysis of multi-class pesticides in turmeric rhizome and powder matrices with satisfactory selectivity, sensitivity, accuracy, and precision. The method performance satisfied the requirements of the SANTE/12682/2019 guidelines, and the method sensitivity complied with the EU-MRL requirements.

Development and validation of a multiresidue method for pesticides and selected veterinary drugs in animal feed using liquid- and gas chromatography with tandem mass spectrometry.

Animal feeds are often reported to be contaminated with chemical residues, and when present above the maximum legal limit, these compounds can cause harmful effects to consumers of animal produce. Thus, animal feed safety is an important regulatory concern. The aim of this study was to optimise a multiresidue method for the simultaneous analysis of multi-class pesticides and a number of frequently used veterinary drugs using LC-MS/MS and GC-MS/MS. The method was validated in a range of feed matrices, including maize feed, poultry feed and mixed feed concentrate. The optimised sample preparation workflow involved extraction of feeds (5g) with ethyl acetate (10mL), followed by a freezing step (at -20°C) used for eliminating the matrix co-extractives. The extract was further cleaned by dispersive solid phase extraction with a combination of primary secondary amine, C18 and florisil sorbents. From the cleaned-extract, an aliquot was analysed by GC-MS/MS, while another portion of it was solvent-exchanged to acetonitrile:water (50:50) and then analysed by LC-MS/MS. This method effectively minimised the matrix interferences. A total of 192 pesticides was analysed by GC-MS/MS within a runtime of 22min. The LC-MS/MS method was validated for 187 compounds including 17 veterinary drugs. For most of the compounds, the limit of quantification (LOQ) was 0.01mg/kg. The recoveries at LOQ and higher levels ranged between 70% and 120%, with precision-RSDs of < 20%. The method provided a precise analysis in a wide range of market-feed samples. As shown, the method is suitable for regulatory and commercial testing purposes.

Multi-residue Analysis of Pesticides in Turmeric (Powder and Rhizome) Using Gas Chromatography Tandem Mass Spectrometry.

Turmeric is widely used as an ingredient of food and medicinal products. There exists no validated method for multi-residue analysis of pesticides in turmeric. This study was undertaken to develop a simple and robust method for the quantitative determination of multi-class pesticides in turmeric powder and rhizome by GC-MS/MS. Initially, the samples were soaked in water for 30 min and homogenized to a fine paste. A portion of this paste (2 g) was extracted with acetonitrile (2 mL) and partitioned with hexane (2 mL) after adding 5 mL of 20% NaCl. The cleanup step involved dispersive solid phase extraction with graphitized carbon black (GCB, 5 mg/mL). Its performance was evaluated against primary secondary amine (PSA) and C18 sorbents. The cleaned extract was evaporated to dryness and reconstituted in ethyl acetate before GC-MS/MS analysis. The method was validated for a mixture of 208 multi-class pesticides at 10 ng/g and higher levels (i.e., 20 and 50 ng/g). The findings, which demonstrated a satisfactory recovery and precision (RSDs <20%) for all compounds at 10 ng/g and higher spiking levels, are aligned with the analytical quality control criteria of SANTE/12682/2019 guidelines. The cleanup effect of GCB was much superior to that of PSA, C18, and their combinations. The solvent exchange step with hexane was effective in removing co-extractives and minimizing matrix effects. This method complies with the regulatory requirements and is fit-for-purpose for pesticide residue monitoring in turmeric. The study reports a validated GC-MS/MS method for multi-residue analysis of pesticides in turmeric for the first time. The method provided a high throughput analysis of multi-class pesticides in turmeric rhizome and powder matrices with satisfactory selectivity, sensitivity, accuracy, and precision.

Multiresidue Analysis of Pesticides in Moringa Pods by GC-MS/MS and LC-MS/MS.

Moringa pods are known for their nutritional and health benefits. The cultivation of this crop receives frequent pesticide applications. In the absence of risk assessment data, maximum residue limits of pesticides in this crop are considered at the default level (0.01 mg/kg). However, there exists scarcely any validated method for pesticide residue analysis in this matrix. This study was undertaken to develop and validate a multiresidue method for the simultaneous analysis of multi-class pesticides in moringa pods by gas chromatography-tandem mass spectrometry (GC-MS/MS), and liquid chromatography-tandem mass spectrometry (LC-MS/MS). The homogenized sample (10 g) was extracted with acetonitrile (10 mL). The extract was cleaned by dispersive solid-phase extraction using a combination of 50 mg primary secondary amine, 5 mg graphitized carbon black, and 25 mg C18 sorbents, and was directly analyzed by LC-MS/MS. Another portion of the extract was reconstituted in ethyl acetate before GC-MS/MS analysis. The method was validated as per the SANTE/12682/2019 guidelines using GC-MS/MS (180 pesticides) and LC-MS/MS instruments (203 pesticides). The method provided a satisfactory analysis of the targeted pesticides with good calibration linearity (r2>0.99), high precision (RSD < 20%), and accuracy (recoveries, 70 to 120%). The reconstitution of the acetonitrile extract in ethyl acetate significantly reduced the matrix effects on GC-MS/MS analysis. The use of matrix-matched standards could correct all recoveries. The method offered a large-scale analysis of multi-class pesticides with high accuracy, and precision at 10 ng/g, and higher levels. The method performance complied with the regulatory requirements, and thus, can be implemented in routine testing purposes. The study reports a validated method for large-scale multiresidue analysis of pesticides in moringa matrix for the first time. The method provided a high throughput analysis of multi-class pesticides with satisfactory selectivity, sensitivity, accuracy, and precision.

Multiresidue Pesticides Analysis of Vegetables in Vietnam by Ultrahigh-Performance Liquid Chromatography in Combination with High-Resolution Mass Spectrometry (UPLC-Orbitrap MS).

An ultrahigh-performance liquid chromatography in combination with high-resolution mass spectrometry Thermo Q-Extractive Focus Orbitrap MS has been introduced for analysis of multiclass pesticides in vegetable samples collected in Hanoi, Vietnam. Multiclass pesticides were separated on the Thermo Hypersil Gold PFP column utilizing a gradient of the mobile phase consisting of 5 mM ammonium formate, 0.1% formic acid in deionized water, and methanol. The target analytes were detected in the full-scan mode on Thermo Scientific Q-Exactive Focus Orbitrap MS for quantitation at the optimum operating conditions. These conditions included, but not limit to, the resolution of 70000 at the full width at half maximum in both positive and negative mode, mass range from 80 to 1000 m/z, and optimized parameters for the heated electrospray ionization source. The identification of the analytes in real samples was based on retention times, mass to charge ratios, mass accuracies, and MS/MS spectra at the confirmation mode with the inclusion list of target analytes. The mass accuracies of target analytes were from −4.14 ppm (dinotefuran) to 1.42 ppm (cinosulfuron) in the neat solvent and from −3.91 ppm (spinosad D) to 1.29 ppm (cinosulfuron) in the matrix-matched solution. Target analytes in the vegetable-based matrix were extracted by the QuEChERS method. Some critical parameters of the analytical method such as linearity, repeatability, limit of detection, and limit of quantitation have been evaluated and implemented. Excellent LOD and LOQ of the developed method were achieved at the range of 0.04–0.85 and 0.13–2.9 μg·kg−1, respectively. Intraday and interday repeatability of the analytical signal (peak area, n=6) of the developed method were below 3% and 10%, correspondingly. The matrix effect, extraction recovery, and overall recovery were fully investigated by spiking experiments. Experimental results demonstrated that the ionization suppression or enhancement was the main contribution on the overall recoveries of target analytes. Finally, the in-house validated method was applied to pesticides screening in vegetables samples in local villages in Hanoi, Vietnam. The concentrations of all target analytes were below limit of quantitation and lower than US-FDA or EU maximum residue levels.

Three approaches to minimize matrix effects in residue analysis of multiclass pesticides in dried complex matrices using gas chromatography tandem mass spectrometry

This paper discusses one of the major concerns in pesticide residue analysis: the matrix effect related to gas chromatography (GC), which can adversely affect quantification. In this study, a comparison of approaches for dealing with the matrix effect was investigated for 236 pesticides in complex matrices, including dried herbs (Centaurea cyanus L., Matricaria chamomilla L., Thymus vulgaris L.) and dried fruit (currants, chokeberry), using a modified QuEChERS method and GC–MS/MS analysis. Three approaches were evaluated: (i) using matrix-matched calibration, (ii) adding a mixture of analyte protectants (APs) to every extract or (iii) injection prior to GC–MS/MS analysis. Finally, minimization of the matrix effect to the acceptable levels of −20 to 20% for over 80% of investigated pesticides was found when APs mixture was injected at the beginning of the sequence. In this approach, the matrix effects were significantly weaker for some pesticides than when matrix-matched calibration was used.

Development of a modified QuEChERS method for multi-class pesticide analysis in human hair by GC-MS and UPLC-MS/MS

The present study assessed the suitability of using QuEChERS procedure for the simultaneous determination and quantification of 37 multi-class pesticides in human hair. Matrix co-eluted material had a large influence on instrumental response sensitivity. Purification was needed although dSPE cleanup sorbent selection critically influenced analyte recovery. Optimized protocol using Z-Sep+ sorbent successfully achieved recovery of 28 pesticides with high sensitivity, precision, and accuracy. Limits of detection ranged from 0.2 to 86.6 pg mg−1 and from 0.5 to 6.3 pg mg−1 for GC and UPLC amenable substances respectively. Pyrethroid pesticides were the most influenced by matrix effects which explained the higher limits of quantification retained for these substances. On the contrary, high sensitivity was achieved for UPLC amenable substances (LOD < 1 pg mg−1 for atrazine, deisopropylatrazine, desethylatrazine, and imidacloprid). Suitability for monitoring pesticide exposure was assessed by application of the proposed protocol to samples collected on the field. Hairs of the volunteers were found positive to 8 pesticides with every sample containing at least one residue. Among these pesticides, only 3 were reported as used in local vegetable production, which suggested other sources of exposure. The developed method offers a sensitive, robust, and accessible tool for biomonitoring of human exposure.

Multiclass pesticide analysis in fruit-based baby food: A comparative study of sample preparation techniques previous to gas chromatography–mass spectrometry

With the aim to develop a new gas chromatography–mass spectrometry method to analyze 24 pesticide residues in baby foods at the level imposed by established regulation two simple, rapid and environmental-friendly sample preparation techniques based on QuEChERS (quick, easy, cheap, effective, robust and safe) were compared – QuEChERS with dispersive liquid-liquid microextraction (DLLME) and QuEChERS with dispersive solid-phase extraction (d-SPE). Both sample preparation techniques achieved suitable performance criteria, including selectivity, linearity, acceptable recovery (70–120%) and precision (⩽20%). A higher enrichment factor was observed for DLLME and consequently better limits of detection and quantification were obtained. Nevertheless, d-SPE provided a more effective removal of matrix co-extractives from extracts than DLLME, which contributed to lower matrix effects. Twenty-two commercial fruit-based baby food samples were analyzed by the developed method, being procymidone detected in one sample at a level above the legal limit established by EU.

Pre-column dilution large volume injection ultra-high performance liquid chromatography-tandem mass spectrometry for the analysis of multi-class pesticides in cabbages

Pre-column dilution large volume injection (PD-LVI), a novel sample injection technique for reverse phase ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC–MS/MS), was developed in this study. The PD-LVI UHPLC–MS/MS system was designed by slightly modifying the commercial UHPLC–MS/MS equipment with a mixer chamber. During the procedure of PD-LVI, sample solution of 200μL was directly carried by the organic mobile phase to the mixer and diluted with the aqueous mobile phase. After the mixture was introduced to the UHPLC column in a mobile phase of acetonitrile-water (15/85, v/v), the target analytes were stacked on the head of the column until following separation. Using QuEChERS extraction, no additional steps such as solvent evaporation or residue redissolution were needed before injection. The features of PD-LVI UHPLC–MS/MS system were systematically investigated, including the injection volume, the mixer volume, the precondition time and the gradient elution. The efficiency of this approach was demonstrated by direct analysis of 24 pesticides in cabbages. Under the optimized conditions, low limits of detection (0.00074–0.8ng/kg) were obtained. The recoveries were in the range of 63.3–109% with relative standard deviations less than 8.1%. Compared with common UHPLC–MS/MS technique, PD-LVI UHPLC–MS/MS showed significant advantages such as excellent sensitivity and reliability. The mechanism of PD-LVI was demonstrated to be based on the column-head stacking effect with pre-column dilution. Based on the results, PD-LVI as a simple and effective sample injection technique of reverse phase UHPLC–MS/MS for the analysis of trace analytes in complex samples showed a great promising prospect.

Determination of Over 350 Multiclass Pesticides in Jams by Ultra-High Performance Liquid Chromatography Time-of-Flight Mass Spectrometry (UHPLC-TOFMS)

In this study, a screening method was developed using ultra-high performance liquid chromatography time-of-flight mass spectrometry (UHPLC-TOFMS) for multiclass pesticide analysis in jam samples. The method was based on an experimental database with retention time/accurate mass data for the 353 selected analytes. Compound identification was based on retention time and the accurate mass measurements of the protonated molecules. The limits of detection were below 10 μg kg−1 for 90 % of the studied compounds. The proposed method was successfully applied to evaluate the presence and concentration levels of over 350 multiclass pesticides in a total of 54 jam market samples collected in Spain from different companies. Results found were in compliance with the current regulations with the exception of a sample, which contained monocrotophos. Forty-one percent of the samples were found free of pesticides; 26 % of the samples contained only one pesticide while 33 % contained at least two or more pesticides.

Multiresidue analysis of multiclass pesticides and polyaromatic hydrocarbons in fatty fish by gas chromatography tandem mass spectrometry and evaluation of matrix effect

This paper reports a selective and sensitive method for multiresidue determination of 119 chemical residues including pesticides and polyaromatic hydrocarbons (PAH) in high fatty fish matrix. The novel sample preparation method involved extraction of the target analytes from homogenized fish meat (5g) in acetonitrile (15mL, 1% acetic acid) after three-phase partitioning with hexane (2mL) and the remaining aqueous layer. An aliquot (1.5mL) of the acetonitrile layer was aspirated and subjected to two-stage dispersive solid phase extraction (dSPE) cleanup and the residues were finally estimated by gas chromatography mass spectrometry with selected reaction monitoring (GC–MS/MS). The co-eluted matrix components were identified on the basis of their accurate mass by GC with quadrupole time of flight MS. Addition of hexane during extraction and optimized dSPE cleanup significantly minimized the matrix effects. Recoveries at 10, 25 and 50μg/kg were within 60–120% with associated precision, RSD<11%.

Headspace Solid Phase Microextraction (HS-SPME) coupled to Gas Chromatography-Mass Spectrometry (GC/MS) for the Analysis of Multi-Class Pesticides

The development of a method based on headspace solid phase microextraction (HS-SPME) technique, for the simultaneous determination of 7 multiclass and multiresidue pesticides (fenobucarb, diazinon, chlorothalonil, thiobencarb,chlorpyrifos,endosulfan I and endosulfan II) in two species of apple, using gas chromatography-mass spectrometry is discussed. The different parameters affecting the SPME technique were evaluated. The extraction capacity of three fiber coatings; polydimethylsiloxane (100µm PDMS), polyacrylate (65µm PA), and polydimethylsiloxane-divinylbenzene (85µm PDMS-DVB), were studied and compared. Validation of the method using two apple species spiked with standard solution yield better linear range, accuracy, precision, detection and quantification limits. The linearity was between 5 to 500 µg.kg–1 with good correlation coefficients (R) greater than 0.989. The average recoveries for all pesticides investigated were between 89–100% in green apple and 94–103% in red apple with RSD ranging from 0.67–3.32% and 1.00 - 2.69 % respectively. The LOQs were between 6.71 and 14.56 µg.kg–1 and LODs ranged from 2.23 to 11.11 µg.kg-1.