Determination of azoxystrobin, topramezone, acetamiprid, fluometuron and folpet in their commercially available pesticide formulations by liquid chromatography.

A rapid, simple, precise and accurate high performance liquid chromatographic (HPLC) analytical method was developed and validated for the determination of the active substances (a.s.) azoxystrobin, topramezone, acetamiprid, fluometuron and folpet in their respective commercially available formulations. The method was used for the analysis of samples under the frame of the national quality control program of plant protection products in the Greek market. Chromatographic separation of the active substances from additives and co-formulants is achieved using isocratic elution with acetonitrile and 0.1% phosphoric acid solution (60:40 v/v) at a flow rate of 0.4 mL min-1 on a C18 monolithic column (Chromolith Performance-RP18e 100 × 4.6 mm) and UV detection at 230 nm. Validation parameters of the method fulfilled acceptability criteria. Recovery of all individual compounds was in the range 97.8-100.9%. Precision expressed as relative standard deviation was lower than the theoretical values of the modified Horwitz equation. Correlation coefficients of linearity of response were better than 0.999. The benefits of the proposed method are significant reduction in analysis time and total cost since all analytes were determined with the same extraction procedures and chromatographic system. Analysis of real samples for all active ingredients confirmed fitness for purpose of the suggested method.

Cohort-friendly protocol for the determination of two urinary biomarkers of exposure to pyrethroids and neonicotinoids using gas chromatography-triple quadrupole mass spectrometry.

Neonicotinoids (NEOs) and synthetic pyrethroids (PYRs) are active ingredients of commercial pesticides and/or insecticides with extensive indoor and outdoor applications, worldwide. Improved exposure metrics are warranted for NEOs and PYRs, if we are to better understand their human health effects. A cohort-friendly protocol for determining non-specific biomarkers of exposure to NEOs and PYRs, e.g. 6-chloronicotinic acid (6-CN) and 3-phenoxybenzoic acid (3-PBA), respectively, in human urine voids was proposed. A series of optimization experiments were conducted to validate the bioanalytical protocol using gas chromatography coupled with triple quadrupole mass spectrometry (GC-QqQ-MS/MS) in MRM mode. The method reached low detection limits for both analytes (0.075 µg L-1 for 6-CN and 0.050 µg L-1 for 3-PBA) in a short preparation and analysis time. The method used small initial urine sample volume (2 mL), short extraction time (≈ 240 min for the batches of 32 samples) and instrumental analysis time (≈ 14 min) for both pesticide metabolites in a single run. This protocol could facilitate the assessment of population exposure metrics for these pesticides and their inclusion in health risk assessment. Graphical abstract.

Quantification of DEET and neonicotinoid pesticide biomarkers in human urine by online solid-phase extraction high-performance liquid chromatography-tandem mass spectrometry.

Neonicotinoid insecticides are widely used replacements for organophosphate and carbamate insecticides, but the extent of human exposure is largely unknown. On the other hand, based on urinary concentrations of DEET metabolites, human exposure to N,N-diethyl-m-toluamide (DEET) appears to be widespread. We developed a fast online solid-phase extraction high-performance liquid chromatography-isotope dilution tandem mass spectrometry (HPLC-MS/MS) method to measure in 200 µL of human urine the concentrations of six neonicotinoid biomarkers (acetamiprid, N-desmethyl-acetamiprid, clothianidin, imidacloprid, 5-hydroxy-imidacloprid, thiacloprid), and two DEET biomarkers (3-diethyl-carbamoyl benzoic acid, 3-ethyl-carbamoyl benzoic acid). Limits of detection ranged from 0.01 to 0.1 µg/L, depending on the biomarker. Accuracy ranged from 91 to 116% and precision ranged from 3.7 to 10 %RSD. The presented method can be used to increase our understanding of exposure to neonicotinoid insecticides and DEET, and to evaluate the potential health effects from such exposures.