Development and validation of an analytical methodology based on solvent extraction and gas chromatography for determining pesticides in royal jelly and propolis

We propose a new analytical methodology to determine seven pesticides (atrazine, chlorpyrifos, chlorfenvinphos, α-endosulfan, bromopropylate, coumaphos, and τ-fluvalinate) in royal jelly and propolis products using gas chromatography-mass spectrometry. Sample treatment, with minor modifications for propolis, consisted of a solvent extraction with a hexane and isopropanol mixture, and a further clean-up step. Meanwhile, chromatographic analysis (<25 min) was performed in a DB-5MS column under programmed temperature conditions. In all cases we validated the method in terms of selectivity, limits of detection (0.1-2.8 μg kg-1) and quantification (0.3-9.2 μg kg-1), linearity, matrix effect (<±20 %), trueness (recoveries between 93 % and 118 %), and precision (relative standard deviation < 11 %). All royal jelly liquid dietary supplements were positive for chlorfenvinphos and, in the case of one of them, for α-endosulfan; chlorfenvinphos was determined in some fresh royal jelly samples, and no pesticide residues were detected in the propolis samples analysed.

Development and Validation of a Gas Chromatography-Mass Spectrometry Method for Determining Acaricides in Bee Pollen

Pesticides can be found in beehives for several reasons, including contamination from surrounding crops or for their use by beekeepers, which poses a risk to bee ecosystems and consumers. Therefore, efficient and sensitive methods are needed for determining pesticide residues in bee products. In this study, a new analytical method has been developed and validated to determine seven acaricides (atrazine, chlorpyrifos, chlorfenvinphos, α-endosulfan, bromopropylate, coumaphos, and τ-fluvalinate) in bee pollen using gas chromatography coupled to mass spectrometry. After an optimization study, the best sample treatment was obtained when using a modified QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe) method employing an ethyl acetate and cyclohexane as the extractant mixture, and a mixture of salts for the clean-up step. A chromatographic analysis (<21 min) was performed in an Agilent DB-5MS column, and it was operated under programmed temperature conditions. The method was fully validated in terms of selectivity, limits of detection (0.2–3.1 µg kg−1) and quantification (0.6–9.7 µg kg−1), linearity, matrix effect (<20% in all cases), trueness (recoveries between 80% and 108%), and precision. Finally, the proposed method was applied to analyze commercial bee pollen samples, and some of the target pesticides (chlorfenvinphos, α-endosulfan, coumaphos, and τ-fluvalinate) were detected.

An accurate and robust LC-MS/MS method for the quantification of chlorfenvinphos, ethion and linuron in liver samples

A method for the determination of chlorfenvinphos, ethion and linuron in liver samples by LC-MS/MS is described. Sample treatment was performed by using Sola™ polymeric reverse phase SPE cartridges after protein precipitation. Gradient elution using 10 mM ammonium formate in methanol (A) and 10 mM ammonium formate in water (B) was used for chromatographic separation of analytes on a Hypersil™ end-capped Gold PFP reverse phase column (100 mm × 2.1 mm, 3 μm). All analytes were quantified without interference, in positive ionization mode using multiple reaction monitoring (MRM) with chlorfenvinphos-d10 as internal standard. The whole procedure was validated according to the FDA guidelines for bioanalytical methods. The calibration curves for chlorfenvinphos, linuron and ethion compounds were linear over the concentration range of 0.005-2 μM (i.e. 0.0018-0.720 μg/mL, 0.0019-0.770 μg/mL and 0.0012-0.500 μg/mL respectively) with coefficients of determination higher than 0.998. A Lower limit of quantification of 0.005 μM was achieved for all analytes, i.e. 5.76, 6.08 and 3.84 μg/kg of liver for chlorfenvinphos, ethion and linuron respectively. Compounds extraction recovery rates ranged from 92.9 to 99.5% with a RSD of 2.3%. Intra- and inter-day accuracies were within 90.9 and 100%, and imprecision varied from 0.8 to 8.2%. Stability tests proved all analytes were stable in liver extracts during instrumental analysis (+12 °C in autosampler tray for 72 h) at the end of three successive freeze-thaw cycles and at -20 °C for up to 9 months. This accurate and robust analytical method is therefore suitable for contamination or metabolism studies.

Comparison and evaluation of pesticide monitoring programs using a process-based mixture model

A number of European countries run large-scale pesticide monitoring schemes in watersheds aimed at identifying and evaluating the presence of pesticide residues in the environment. These schemes provide national and regional scale assessments of pesticide concentrations within the context of environmental quality assessment, aiming to ensure some degree of ecological protection. The present study is aimed at evaluating the joint effects of the pesticide mixtures detected in monitoring programs, using a process-based mixture model that was parameterized for Daphnia magna. In total, over 15 000 samples containing over 1 million individual measurements were evaluated for effects. It was found that there are only a small number of places where one can expect to have effects on daphnids, based on measured concentrations. The most polluted samples would cause extinction of a daphnid population within only 30 h. The results show that effects are mostly triggered by a limited number of pesticide residues at locations with high emissions. It was also shown that the analytical detection limits are basically too high to exclude mixture effects. So, despite all the effort that is put into chemical monitoring programs, it remains a challenge to make statements on whether or not the environment is protected. Recommendations are offered for a different setup of monitoring programs to improve this situation. Environ Toxicol Chem 2016;35:3113-3123. © 2016 SETAC.

Effect of processing on 14C-chlorfenvinphos residues in maize oil and bioavailability of its cake residues on rats

Maize seeds obtained from 14C-chlorfenvinphos treated plants contained 0.12% of the applied dose. The insecticide residues in crude oil, methanol and cake amounted to 10%, 6% and 69%, respectively of original residues inside the seeds. The 14C-activity in the crude oil could be a gradually reduced by the refining processes. The alkali treatment and bleaching steps are the most effective steps in these processes. The refined oil contained small amount of the 14C-residues originally present. The major residues in processed oil contain the parent compound, in addition to five metabolites of the insecticide. When rats fed the extracted seeds (cake), the bound residues were found to be considerably bioavailability. After feeding rats for five days with the cake, a substantial amount of 14C-residues was eliminated in the urine (59.5%), while about 20% excreted in the feces. About 15% of the radioactive residues were distributed among various organs.

Biosensor-controlled degradation of chlorpyrifos and chlorfenvinfos using a phosphotriesterase-based detoxification column

This works presents the development of a detoxification system based on bacterial phosphotriesterase (PTE) for the degradation of organophosphate (OP) insecticides in water. PTE was immobilised on an activated agarose gel via covalent coupling. Two different OPs were studied, chlorpyrifos and chlorfenvinfos, due to their importance in the field of water policy. The efficiency of insecticide degradation was controlled using a highly sensitive biosensor allowing the detection of OP concentration as low as 0.004 microgL(-1). Under optimum conditions, it was shown that a column incorporating 500IU of PTE was suitable for the detoxification of solutions containing either isolated pesticides or pesticides mixtures, even at concentrations higher than authorized limits. Finally, the method was shown to be adapted to the decontamination of real samples of pesticides with concentrations up to 20 microgL(-1).

Separation of uncertainty and interindividual variability in human exposure modeling

The NORMTOX model predicts the lifetime-averaged exposure to contaminants through multiple environmental media, that is, food, air, soil, drinking and surface water. The model was developed to test the coherence of Dutch environmental quality objectives (EQOs). A set of EQOs is called coherent if simultaneous exposure to different environmental media that are all polluted up to their respective EQOs does not result in exceeding the acceptable or tolerable daily intake (ADI or TDI). Aim of the present study is to separate the impact of uncertainty and interindividual variability in coherence predictions with the NORMTOX model. The method is illustrated in a case study for chlorfenvinphos, mercury and nitrate. First, ANOVA was used to calculate interindividual variability in input parameters. Second, nested Monte Carlo simulation was used to propagate uncertainty and interindividual variability separately. Lifetime-averaged exposure to chlorfenvinphos, mercury and nitrate was modeled for the Dutch population. Output distributions specified the population fraction at risk, due to a particular exposure, and the reliability of this risk. From the case study, it was obtained that at lifelong exposure to all media polluted up to their standard, 100% of the Dutch population exceeds the ADI for chlorfenvinphos, 15% for mercury and 0% for nitrate. Variance in exposure to chlorfenvinphos, mercury and nitrate is mostly caused by interindividual variability instead of true uncertainty. It is concluded that the likelihood that ADIs of chlorfenvinphos and mercury will be exceeded should be further explored. If exceeding is likely, decision makers should focus on identification of high-risk subpopulations, rather than on additional research to obtain more accurate estimates for particular parameters.

Organophosphorus pesticide residues in Mexican commercial pasteurized milk

A study was conducted to measure residues of 13 organophosphorus (OP) pesticides, widely used as dairy cattle ectoparasiticides or in crops used for animal feed, in homogenized and pasteurized Mexican milk samples. Four different milk brands with high distribution were collected biweekly during a 12 month period (n = 96) in supermarkets. OP pesticide residues were measured by gas chromatography with a flame photometric detector. Approximately 39.6% of the samples contained detectable levels of OP pesticide residues. Eight samples contained residues exceeding established maximum residue limits (MRL), and the OP pesticides present in these samples were dichlorvos (five samples), phorate, chlorpyrifos, and chlorfenvinphos (one sample, respectively). Average residues of 13 OP pesticides measured were below established MRLs ranging between 0.0051 and 0.0203 ppm.

Convenient and rapid detection of pesticides in extracts of sheep wool

A relatively simple, rapid extraction technique based on acetonitrile was combined with the use of screen-printed electrodes bearing cholinesterases to detect organo-phosphate pesticides from an otherwise intractable matrix, sheep wool. It proved possible to separate, for convenience, the exposure of the electrodes from measurement of their (inhibited) activity. The electrodes were used once and then discarded. Estimation of the extent of inhibition is dependent on reference to the activity of control electrodes. The presence of pesticides in the extracts could be detected with any of three commonly available cholinesterases but the most sensitive enzyme was butyryl cholinesterase from horse serum.

Pesticides in precipitation in the Gdańsk region (Poland)

Selected organonitrogen, organophosphorus and organochlorine pesticides have been determined in precipitation samples collected at 10 sites in the Gdańsk region (northern Poland) over a period of one year (1998). Compounds which were detected most often included simazine (0.11-5.80 ng/l), fenitrothion (0.1-2.10 ng/l), chlorfenvinfos (0.1-1.30 ng/l), gamma-HCH (0.012-5.06 ng/l), heptachlor epoxide (0.05-3.28 ng/l) and aldrin (0.02-3.28 ng/l). The pesticide concentrations in precipitation samples revealed seasonal fluctuations, with higher concentrations observed during the application periods (June and July). The concentrations observed were also affected by the inflow of polluted air masses from the southwest. The total pesticide concentration in the precipitation samples was strongly related to the abundance of green areas in the vicinity of the sampling sites. A weak correlation was also found between the total concentration of organonitrogen and organophosphorus pesticides, and the total concentration of organochlorine pesticides in the samples collected.