Chang, Chunxin, et al. Analytical Methods, 2016, 8(22), 4487-4496.
This research developed a technique to measure 20 organophosphorus pesticides in human serum at the same time. A small 200-microliter serum sample underwent solid phase extraction before triple quadrupole mass spectrometry gas chromatography (GC-MS/MS) analysis. The three isotope-labeled internal standards used were dimethoate D6, alachlor D13, and chlorpyrifos D10, with a purity of > 95%. The figure on the right shows the types of organophosphorus pesticides detected by GC-MS/MS and the method settings.
Among 20 tested pesticides, the lowest detection level was 0.01 ng mL-1 while the highest was 2.70 ng mL-1. Quantification limits spanned from 0.05 ng mL-1 to 9.00 ng mL-1. Linearity ranged from 0.02 ng mL-1 to 135.00 ng mL-1. The recovery percentage ranged from 90% to 120%. In spiked serum samples the relative standard deviation of organophosphorus pesticides stayed under 15% during both daily and inter-day measurements at 2.70 and 27.00 ng mL-1 levels.
Sample preparation: Blood serum samples received isotope-labeled internal standards (Dimethoate D6, Alachlor D13, and Chlorpyrifos D10) before protein precipitation with saturated ammonium sulfate solution. The supernatant from the protein precipitation was purified through a C18 solid-phase extraction cartridge. After cleaning with dichloromethane and methanol the SPE device produced eluate that was dried and reconstituted in toluene before GC-MS/MS testing.
