Development of One-Step Non-Solvent Extraction and Sensitive UHPLC-MS/MS Method for Assessment of N-(n-Butyl) Thiophosphoric Triamide (NBPT) and N-(n-Butyl) Phosphoric Triamide (NBPTo) in Milk

N-(n-butyl) thiophosphoric triamide (NBPT) is a urease inhibitor utilised in urea-based fertilizers. In Ireland, fertilizer treated with NBPT is applied to pasture to mitigate both ammonia and nitrous oxide emissions, but concerns arise as to the potential for residues in milk products. A quick ultrafiltration extraction and ultra-high performance liquid chromatography coupled with mass spectrometry triple quadrupole (UHPLC-MS/MS) quantitation method was developed and validated in this study. The method was applied in the analysis of samples collected from a field study investigating potential transfer of NBPT residues into milk. NBPT and NBPTo residues, were extracted from fortified milk samples and analysed on a UHPLC-MS/MS with recoveries ranging from 74 to 114%. Validation of the UHPLC-MS/MS method at low (0.0020 mg kg⁻¹) and high (0.0250 mg kg⁻¹) concentration levels in line with SANTE/12682/2019 showed overall trueness in the range of 99 to 104% and precision between 1 and 10%, RSD for both compounds. The limit of quantitation (LOQ) was 0.0020 mg kg⁻¹ and other tested parameters (linearity, sensitivity, specificity, matrix effect, robustness, etc.) satisfied acceptance criteria. Stability assessment using spiked samples revealed the compounds were stable in raw and pasteurised milk for 4 weeks at –80 °C storage temperature. Maintaining samples at pH 8.5–9.0 further improved stability. Analysis of 516 milk samples from the field study found that NBPT and NBPTo concentrations were below the LOQ of 0.0020 mg kg⁻¹, thus suggesting very low risk of residues occurring in the milk. The method developed is quick, robust, and sensitive. The method is deemed fit-for-purpose for the simultaneous determination of NBPT and NBPTo in milk.     

Homogeneous liquid-liquid extraction combined with gas chromatography-electron capture detector for the determination of three pesticide residues in soils

In this study, a new method was developed for analyzing malathion, cypermethrin and lambda-cyhalothrin from soil samples by using homogeneous liquid–liquid extraction (HLLE) and gas chromatography with electron capture detector (GC–ECD). Acetone was used as extraction solvent for the extraction of target pesticides from soil samples. When the extraction process was finished, the target analytes in the extraction solvent were rapidly transferred from the acetone extract to carbon tetrachloride, using HLLE. Under the optimum conditions, linearity was obtained in the range of 0.05–40 μg kg⁻¹ for malathion, 0.04–10 μg kg⁻¹ for lambda-cyhalothrin and 0.05–50 μg kg⁻¹ for cypermethrin, respectively. Coefficients of correlation (r²) ranged from 0.9993 to 0.9998. The repeatability was carried out by spiking soil samples at concentration levels of 2.5 μg kg⁻¹ for lambda-cyhalothrin, and 10 μg kg⁻¹ for malathion and cypermethrin, respectively. The relative standard deviations (RSDs) varied between 2.3 and 9.6% (n = 3). The limits of detection (LODs), based on signal-to-noise ratio (S/N) of 3, varied between 0.01 and 0.04 μg kg⁻¹. The relative recoveries of three pesticides from soil A1, A2 and A3 at spiking levels of 2.5, 5 and 10 μg kg⁻¹ were in the range of 82.20–91.60%, 88.90–110.5% and 77.10–98.50%, respectively. In conclusion, the proposed method can be successfully applied for the determination of target pesticide residues in real soil samples.     

Determination of carbendazim,thiabendazole, and<Emphasis Type="Italic"> o-</Emphasis>phenylphenol residues in lemons by HPLC following sample clean-up by ion-pairing

An efficient analytical method is presented involving effective sample clean-up with solid-phase extraction and HPLC-UV analysis for the simultaneous determination of carbendazim, thiabendazole, and o-phenylphenol residues in lemons. Sample preparation involves extraction with acetonitrile acidified with trifluoroacetic acid and an ethyl acetate/petroleum ether mixture. Purification of the crude extract was carried out with liquid–liquid partitioning after addition of an aqueous ammonia solution. Final clean-up was performed on polymeric reversed-phase cartridges pretreated with sodium dodecyl sulfate. Chromatographic analysis was performed on a reversed-phase HPLC column isocratically eluted with an acetonitrile/water/ammonia mixture and UV detection at 254 nm. The chromatographic method is repeatable, reproducible, and sensitive. Fungicide recoveries from lemon samples fortified at levels of 5 and 1 mg kg^–1 were 81–85% for carbendazim, 96–98% for thiabendazole, and 81–106% for o-phenylphenol with coefficients of variation of 2.5–7.4%. Detection limits for carbendazim, thiabendazole, and o-phenylphenol in lemons were 0.21, 0.27, and 0.51 mg kg^–1, respectively.     

Monitoring of sulfonamide antibacterial residues in milk and egg by polymer monolith microextraction coupled to hydrophilic interaction chromatography/mass spectrometry

A simple, rapid, and sensitive method for the determination of traces of thirteen sulfonamide antibacterials in milk and eggs is presented. This method is based on the combination of polymer monolith microextraction (PMME) technique with hydrophilic interaction chromatography/mass spectrometry (HILIC/MS). The extraction was performed with a poly(methacrylic acid-ethylene glycol dimethacrylate) monolithic capillary column while the subsequent separation was carried out on a Luna NH₂ column by HILIC. To obtain optimum results, several parameters relating to HILIC and PMME were investigated. After optimization, acetonitrile (contain 0.05% formic acid, v/v) was used as the elution solution, which was well compatible with the mobile phase in HILIC. Good linearities were obtained for thirteen SAs with the correlation coefficients (R²) above 0.997. The limits of detection (S/N = 3) of the method were found to be 0.4–5.7 ng mL⁻¹ of SAs in whole milk and 0.9–9.8 ng g⁻¹ of SAs in eggs. The recoveries of thirteen SAs in two matrices ranged from 80.4 to 119.8%, with relative standard deviations less than 11.8%.     

New methods for acceleration of meat sample preparation prior to determination of the metal content by atomic absorption spectrometry

Focused microwave-assisted digestion and ultrasound leaching have been applied for the extraction of Pb, Cd, Cr, Cu, Fe, Zn, Ca, and Mg from raw meat. Semimembranous muscle (SM) of raw pig ham was used for optimizing both the digestion and extraction steps by multivariate approaches. The detection and quantification limits were 0.5 and 0.9 g kg^–1 for Pb, 0.06 and 0.1 g kg^–1 for Cd, 0.2 and 1.2 g kg^–1 for Cr, 0.4 and 3 g kg^–1 for Cu, 0.04 and 0.1 mg kg^–1 for Fe, 0.012 and 0.017 mg kg^–1 for Zn, 0.3 and 0.4 mg kg^–1 for Ca, and 0.01 and 0.03 mg kg^–1 for Mg. The precision, expressed as relative standard deviation (RSD), ranged between 2.5 and 9.6% for focused microwave-assisted digestion and between 3.5 and 10.6% for ultrasound leaching. The methods were then compared with a reference method and applied to a certified reference material (bovine muscle 184, from the BCR). The t-test, applied to the results obtained from focused microwave-assisted digestion, revealed that they are in agreement (p>0.01) with the certified and estimated values in the case of Pb, Cd, Cr, Cu, Fe, Ca, Mg, and Zn but not in that of Fe. In the case of ultrasound leaching, only the extraction of Pb, Cu, and Ca was quantitative. The method based on microwave digestion provides more accurate and precise results than ultrasound leaching. These new procedures have many advantages with regards to conventional methods, namely, reduction of the extraction time, simplification of the process, avoidance of chemical emissions to the atmosphere, and no losses of metals by volatilization.     

Monitoring and Exposure Assessment of Fosetyl Aluminium and Other Highly Polar Pesticide Residues in Sweet Cherry

Cherries are popular fruits due to their health benefits, organoleptic quality, and attractive appearance. Since highly polar pesticides are of low mass and amphoteric character, and are not amenable to traditional multi-residue extraction methods, they are more commonly not included in the pesticide monitoring program. This study aims to determine twelve highly polar pesticide residues in cherry samples intended for export from Turkey. A total of 16,022 cherry samples from 2018–2020 harvests in four production areas of Turkey were analyzed using a modification of the Quick Polar Pesticides method and liquid chromatography-tandem mass spectrometry. The method was validated at two fortification levels (0.01 and 0.05 mg kg⁻¹), and good recoveries (87.4–111.4%) and relative standard deviations (<6%) were achieved for all analytes. The limits of quantification were in the range of 1.08–2.55 μg kg⁻¹. Overall, 28.4% of the analyzed cherry samples were detected with phosphonic acid, calculated as fosetyl aluminium (fosetyl-Al) in amounts up to 77.7 mg kg⁻¹. For 2304 samples (14.4%), the residues exceeded the European Union maximum residue level of 2 mg kg⁻¹. There is no reason to be concerned about long-term exposure to phosphonic acid/fosetyl-Al, and the other highly polar pesticides through the consumption of sweet cherry.     

Use of High-Performance Liquid Chromatography–UV and Gas Chromatography–Mass Spectrometry for Determination of the Imidacloprid Content of Honeybees, Pollen, Paper Filters, Grass, and Flowers

Imidacloprid is a new insecticide with a wide range of action. Because honeybees are very sensitive to this substance, two techniques (HPLC–UV and GC–MS) which enable its detection in several matrices of both animal and vegetable origin were used to monitor its possible presence in cultivated land. In the first method quantification of imidacloprid in honeybees was achieved by use of the external standard method; the detection limit was 50 mg kg^–1, the linear range 0.05–1 mg mL^–1, recovery 60–83%, and the imprecision (coefficient of variation) 8.6% for repeatability and 11.8% for reproducibility. Recovery from pollen was 71–98% in the range 0.05–0.5 mg kg^–1. The repeatability was 9.2–13.9%. Imidacloprid can often be found in the environment, not as a simple molecule but as a group of degradation products. The GC–MS method could be used to quantify all these species as oxidation products and to determine the initial quantity of imidacloprid by use of a conversion factor. The liquid chromatographic analysis could be used to detect, in a standard solution, 10 ng mL^–1 derivatized 6-chloronicotinic acid. The linearity was good (R=0.999) over a wide concentration range (10 g mL^–1–10 ng mL^–1). Several samples with different matrices (filter paper placed on an pneumatic corn seed drill, grass, flowers, honeybees, etc.) obtained during the sowing period for imidacloprid-treated corn were analyzed. The quantification limit (LOQ) was 0.005 mg kg^–1 for grass and flowers, 0.002 mg kg^–1 for honeybees, and 0.024 mg kg^–1 for paper filters.     

Indirect determination of chloride and sulfate ions in alcohol fuel by capillary electrophoresis

A capillary zone electrophoresis method using indirect UV detection for the analysis of chloride and sulfate in alcohol fuel samples was developed. The anions were analyzed in less than 3 min using an electrolyte containing 10 mmol l^–1 chromate and 0.75 mmol l^–1 hexamethonium bromide (HMB) as electroosmotic flow modifier. Coefficients of variation were better than 0.6% for migration time (n=10) and between 2.05 and 2.82% for peak area repeatabilities. Analytical curves of peak area versus concentration in the range of 0.065–0.65 mg kg^–1 for chloride and 0.25–4.0 mg kg^–1 for sulfate were linear with coefficients of correlation higher than 0.9996. The limits of detection for sulfate and chloride were 0.033 and 0.041 mg kg^–1, respectively. Recovery values ranged from 85 to 103%. The method was successfully applied for the quantification of sulfate and chloride in five alcohol fuel samples. The concentration of sulfate varied from 0.45 to 3.12 mg kg^–1. Chloride concentrations were below the methods LOD.     

Determination of phenylurea and triazine herbicides in milk by microwave assisted ionic liquid microextraction high-performance liquid chromatography

The determination of phenylurea and triazine herbicides in milk based on microwave assisted ionic liquid microextraction (MAILME) coupled with high-performance liquid chromatographic separation was described. The experimental parameters of the MAILE, including type and amount of ionic liquid, microwave extraction power, extraction time and salt concentration in sample, were evaluated by a univariate method and orthogonal screening. When 60 μL of [C₆MIM][PF₆] was used as extraction solvent the target compounds can be isolated from the 4 mL of milk. The MAILME is quick (7 min) and simple. The detection limits for isoproturon, monolinuron, linuron, propazine, prometryne, terbutryn and trietazine are 0.46, 0.78, 1.00, 1.21, 1.96, 0.84 and 1.28 μg L⁻¹, respectively. The proposed method was applied to the analysis of milk samples and the recoveries of the analytes ranged from 88.4 to 117.9% and relative standard deviations were lower than7.43%.     

Determination of Aniline in Soil by ASE/GC-MS

In this study, a rapid and simple method based on accelerated solvent extraction (ASE) combined with gas chromatography-mass spectrometry (GC-MS) was established to determine the levels of aniline in soil. The matrix spike recovery rates of aniline were investigated by changing several experimental parameters such as vacuum freeze-drying, accelerated solvent extraction, sample transfer, nitrogen-blowing concentration and solvent exchange. Under optimized pretreatment conditions, the linearity of the method ranged from 0.5 to 20 μg mL⁻¹ for aniline, and the correlation coefficient was 0.999. Recoveries of aniline from quartz sand and soil ranged from 76% to 98%, while the precision was excellent with average inter-day and intraday values ranging (n = 6) from 3.1% to 7.5% and 2.0% to 6.9%, respectively. The limits of quantification of the method were 0.04 mg kg⁻¹. Notably, the results show that the method we developed is simple, fast, low cost and can meet the requirements for the determination of aniline in soil samples, sewage sludge, river and pond sediments.     

Preconcentration extractive separation, speciation and spectrometric determination of iron(III) in environmental samples

Preconcentration, speciation and separation with solvent extraction of Fe(III) from samples of different origin, using methyl isobutyl ketone (MIBK) as a solvent and the sodium salt of 2-carboethoxy-1,3-indandione (CEIDNa) as a complexing agent for Fe(III), were studied. CEIDNa reacts with Fe(III) in the pH range 1.5–3.5 to produce a red colored complex of Fe(III)–CEIDNa (1:3 molar ratio) soluble in MIBK. The investigation includes a study of the characteristics that are essential for solvent extraction, spectrophotometric and flame atomic absorption spectrometric determination (AAS) of iron. A highly sensitive, selective and rapid spectrometric method is described for the trace analysis of iron(III) by CEIDNa. The complex formed obeys Beer's law from 0.06 to 1.8 mg l⁻¹ with an optimum range. A single step extraction was efficiently used with a distribution ratio (D)=10^3.6. The extracted red colored (1:3) Fe–CEIDNa was measured spectrophotometrically at 500 nm with a molar absorptivity of 1.2×10⁴ l mol⁻¹ cm⁻¹. In addition, the organic phase was directly aspirated to the flame for AAS determination and the signals related to Fe(III) concentration were recorded at 243.3 nm. The complexation of iron(III) with CEIDNa allows the separation of the analyte from alkali, alkaline earth and other elements, which are not complexed. The proposed preconcentration procedure was applied successfully to the determination of trace Fe(III) in soil, milk and natural water samples.     

Multiresidue analysis of phenylurea herbicides in environmental waters by capillary electrophoresis using electrochemical detection

A rapid multiresidue method has been developed for the analysis of seven phenylurea herbicides in the presence of two s-triazines in environmental waters. A simple end-column electrochemical detector was used in combination with a commercially-available capillary electrophoresis instrument with UV detection. The determination of phenylurea pesticides using micellar electrokinetic capillary chromatography with electrochemical detection represents the first such determination that has been reported. In both detection systems, linear ranges were obtained for the seven phenylurea herbicides at concentrations lower than 2.0×10^–5 mol l^–1, in 0.020 mol l^–1 phosphoric acid at pH 7.0 and containing 0.020 mol l^–1 of sodium dodecylsulfate, in order to obtain selectivity in the additional separation by a micellar distribution process. Under these conditions a detection limit lower than 5.0×10^–6 mol l^–1 (0.25 pmol of pesticide) was achieved for most of them. The pesticides were resolved in less than 30 min.     

Food engineering residues: amino acid composition of hydrolysates and application for the decontamination of metal polluted soils

Several residues of the brewing industry and slaughtering offals were investigated in order to evaluate their potential as raw materials for the hydrolytic preparation of amino acid containing solutions, applicable as extractants in amelioration processes for metal polluted soils. The residues were hydrolysed with 6 mol/L hydrochloric acid and the hydrolysates were analysed for their total nitrogen, TOC, amino acid and heavy metal contents. Then, the leaching capacities of the hydrolysates were examined in a series of batch tests with a contaminated soil.High amino acid yields in relation to the weight of the air-dried raw materials were achieved with blood meal (72.5%) and poultry feather meal (56.6%). The portion of the detected amino acids of the total organic carbon content of the hydrolysates ranged from 38.9% (brewer's spent grain) to 93.6% (blood meal). In extraction tests with hydrolysates adjusted to a total amino acid concentration of 60 mmol/L and to a pH value of 7.0, maximum extraction yields of 50.3% for copper (soil content 279 mg kg^–1) and 38.7% for nickel (soil content 54 mg kg^–1) were reached. An increase of the hydrolysate concentration and of the pH of an amino acid mixture resulted in higher solubilisation of the metals.Dedicated to Prof. Dr. Dieter Klockow on the occasion of his 60th birthday     

Determination of low-level ink photoinitiator residues in packaged milk by solid-phase extraction and LC-ESI/MS/MS using triple-quadrupole mass analyzer

A confirmatory and quantitative method based on liquid chromatography–electrospray ionization tandem mass spectrometry (LC-ESI/MS/MS) has been developed for simultaneous determination of seven photoinitiator residues: benzophenone, (1-hydroxycyclohexyl)phenylketone (Irgacure 184), isopropylthioxanthone (ITX), 2-ethylhexyl-(4-dimethylamino)benzoate (EHA or EHDAB), 2-methyl-1-[4-(methylthio)phenyl]-2-(4-morpholinyl)-1-propanone (Irgacure 907), (2,4,6-trimethylbenzoyl)diphenylphosphine oxide (TPO) and 2-benzyl-2-(dimethylamino)-1-(4-morpholinophenyl)-1-butanone (Irgacure 369) in packaged milk and related packaging materials. Residues of photoinitiators were extracted from milk using acetonitrile, and further enriched and purified on HLB solid-phase extraction cartridges prior to being analyzed by LC-ESI/MS/MS with selected reaction monitoring mode, while photoinitiators in packaging materials were extracted using the same solvent. Satisfactory recovery (from 80 to 111%), intra- and inter-day precision (below 12%), and low limits of quantification (from 0.1 to 5.0 μg kg⁻¹) were evaluated from spiked samples at three concentration levels (5.0, 10.0 and 25.0 μg kg⁻¹ for Irgacure 184 and 2.5, 5.0 and 25.0 μg kg⁻¹ for others). These excellent validation data suggested the possibility of using the LC-ESI/MS/MS method for simultaneous determination of low-level photoinitiator residues migrating from printed food-packaging materials into milk. The method has been successfully applied to the analysis of real samples of different fat contents ranging from 8 to 30 g L⁻¹. The photoinitiator residues were revealed to be higher in milk with higher fat content and the most important contaminations were benzophenone and ITX in concentration ranges of 2.84–18.35 and 0.83–8.87 μg kg⁻¹, respectively.     

Confirmatory Analysis of Per and Polyfluoroalkyl Substances in Milk and Infant Formula Using UHPLC–MS/MS

An ultra-high performance liquid chromatography tandem mass spectrometry method was developed and validated for the sensitive determination and unambiguous confirmation of residues of per and polyfluorinated alkyl substances (PFAS) in breastmilk, retail milk and infant formulas following two sample preparation methods. Sample pre-treatment was carried out by a simplified QuEChERS method without requiring dSPE or any further clean-up. The method was validated in accordance with the requirements of Commission Decision 657/2002/EC with slight modifications. The method displayed good linearity with R² ranging from 0.9843–0.9998 for all target PFAS. The recovery and within-laboratory reproducibility of the method (n = 63) were in the range 60–121% and 5–28%, respectively. The decision limit, detection capability and limit of quantitation ranged from 30–60 ng kg⁻¹ to 40–100 ng kg⁻¹ and 5–50 ng kg⁻¹, respectively. Acceptable matrix effect values in the range −45–29% were obtained with uncertainty of measurement lower than 25% for all target PFAS. The method displays its suitability for the sensitive and high-throughput confirmatory analysis of C₄–C₁₄ PFAS in breastmilk, dairy milk and infant formulas.     

Ultrasound-assisted extraction for the analysis of phenolic compounds in strawberries

A semiautomatic method based on application of ultrasounds has been developed to leach and hydrolyse phenolic compounds, such as naringin, rutin, naringenin, ellagic acid, quercetin and kaempferol, from strawberries. Two grams of lyophilized sample was placed into a sample cell and 5 mL of acetone containing hydrochloric acid was added. The cell was immersed in a water bath and sonicated for 30 s (duty cycle 0.8 s, output amplitude 50% of the nominal amplitude of the converter, applied power 100 W and with the probe placed 2 cm from the top surface of the extraction cell) for three times: each time 5 mL extractant displaced the previous extract. When the extraction was completed, the combined extracts were evaporated for 10 min, diluted to 10 mL with water adjusted to pH 8, and transferred to a cleanup–preconcentration manifold; here the analytes were retained in two in-series minicolumns packed with HR-P sorbent and then eluted with 4 mL methanol, and injected for individual separation–quantitation into a chromatograph–photodiode array detector assembly. Optimisation of the extraction was carried out using samples spiked with 4 mg kg^–1 of each analyte. Calibration curves using the standard addition in red strawberries typically gave linear dynamic ranges of 4–40 mg L^–1 for all analytes, except for ellagic acid (40–400 mg L^–1). The r ² values exceeded 0.98 in all cases.     

Determination of pesticides and PCBs in honey by solid-phase extraction cleanup followed by gas chromatography with electron-capture and nitrogen–phosphorus detection

A multiresidue method for determination of 15 organochlorine pesticides (OCPs), six polychlorinated biphenyls (PCBs), and seven organophosphorus pesticides (OPPs) is implemented for routine determinations of residues in honey. The method involves solid-phase extraction cleanup and determination by GC–ECD/NPD. Quantitation limits ranged from 0.1 to 0.6 g kg^–1 honey for OCPs and PCBs, and from 5.0 to 25.0 g kg^–1 honey for OPPs. Recoveries of OCPs ranged between 77.4 and 94.0%; for PCBs they were from 63.8 to 73.5%. Recovery assays for OPPs varied from 66.7 to 98.1%. The method was applied to the analysis of 111 honey samples from Aragón, Spain. The results obtained indicated a low level of contamination by pesticide residues and PCBs, which can contribute to ensuring the consumer has a safe wholesome supply of honey.     

Benzimidazole carbamate residues in milk: Detection by Surface Plasmon Resonance-biosensor, using a modified QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) method for extraction

A surface plasmon resonance (SPR) biosensor screening assay was developed and validated to detect 11 benzimidazole carbamate (BZT) veterinary drug residues in milk. The polyclonal antibody used was raised in sheep against a methyl 5(6)-[(carboxypentyl)-thio]-2-benzimidazole carbamate protein conjugate. A sample preparation procedure was developed using a modified QuEChERS method. BZT residues were extracted from milk using liquid extraction/partition with a dispersive solid phase extraction clean-up step. The assay was validated in accordance with the performance criteria described in 2002/657/EC. The limit of detection of the assay was calculated from the analysis of 20 known negative milk samples to be 2.7 μg kg⁻¹. The detection capability (CCβ) of the assay was determined to be 5 μg kg⁻¹ for 11 benzimidazole residues and the mean recovery of analytes was in the range 81-116%. A comparison was made between the SPR-biosensor and UPLC-MS/MS analyses of milk samples (n = 26) taken from cows treated different benzimidazole products, demonstrating the SPR-biosensor assay to be fit for purpose.     

Ultrasonic extraction and LC determination of linear alkylbenzene sulfonate in plant tissues

Summary A new method has been developed for the extraction and determination of linear alkylbenzene sulfonate (LAS) in plant tissues (rice stems and leaves). It consists of methanol-ultrasonic extraction followed by clean-up with aluminum oxide, enrichment with C₁₈ solid-phase extraction column and determination by HPLC. Both efficiency and accurracy of the overall method were high, i.e. mean recovery of: 89% (84 to 93% for LAS concentrations ranging from 1 to 100 mg kg⁻¹) and repeatability of: 3% relative standard deviation for 6 replicate analyses. With a 2 g sample for analysis, LAS levels of 0.5 mg kg⁻¹ in plants could be detected with the proposed method. Further advantages were: it was less time consuming (1 h for extraction), less solvent consumption, and smaller samples (2 to 3 g) required when compared with Soxhlet extraction.     

Simultaneous Determination of Carbamate and Organophosphorus Pesticides in Honeybees by Liquid Chromatography-Mass Spectrometry

Summary The potential of liquid chromatography-mass spectrometry (LC-MS) has been studied for the simultaneous determination of sixteen carbamate and organophosphorus pesticides in honeybees using a traditional sample preparation protocol based on acetone extraction and dichloromethane partitioning. The performances of both atmospheric pressure chemical ionization (APCI) and electrospray (ES) interfaces were compared. APCI offered better sensitivity and specificity for a higher range of pesticides. Limits of quantification were from 0.01 to 0.17 mg kg^–1, at which recoveries obtained were between 64 and 93%, except for pirimicarb that was at 13%, with relative standard deviations ranging from 7 to 20%. Fenitrothion, fenoxycarb, methiocarb and phoxim were found in bees from Valencian Community beehives at concentrations between 0.03 and 3.75 mg kg^–1.