Pesticides have been used widely on agricultural plants, inhibition of weeds, control of pests, etc. Pesticides and their metabolites may enter the water environment through runoff or air deposition, and their impact on human health and aquatic creatures deserve our attentions. Based on the statistical data from the Council of Agriculture, Taiwan, the most used active ingredients among pesticides are insecticides, bactericides, and herbicides. This study developed and validated a method to analyze 50 insecticides using solid-phase extraction and ultra-high performance liquid chromatography/tandem mass spectrometry (UPLC-MS/MS). There are 27 organophosphates, 16 carbamates, and seven pyrethroids, which including acephate, azinphos-methyl, chlorpyrifos, demeton, demeton-S-methyl, diazinon, dichlorvos, dimethoate, disulfoton, ethoprophos, fenthion, fonofos, isoxathion, malathion, methamidophos, methidathion, mevinphos, monocrotophos, parathion, phenthoate, phorate, phosmet, profenofos, quinalphos, temephos, terbufos, trichlorfon, aldicarb, aldicarb sulfoxide, aldicarb sulfone, benfuracarb, carbaryl, carbofuran, 3-hydroxycarbofuran, carbosulfan, ethiofencarb, fenobucarb, isoprocarb, methiocarb, methomyl, oxamyl, pirimicarb, propoxur, cyfluthrin, cypermethrin, deltamethrin, fenpropathrin, fenvalerate, permethrin, and tau-fluvalinate. 500-mL of water was extracted with Atlantic HLB disk (47 mm) and was eluted with methanol and dichloromethane. The combined eluent was concentrated to 5 mL and was analyzed with the UPLC-MS/MS at positive electrospray ionization. A Phenomenex Kinetex PFP (50 × 2.1 mm, 2.6 μm) core-shell column was used for the chromatography. Samples were collected from three rivers of southern Taiwan (Beigang River, Bajhang River, and Yanshuei River), a reservoir for a drinking water plants, drinking water, and a sewage treatment plant, plus seven drinking water samples from the National Institute of Environmental Analysis (NIEA), in the total of 31 samples. The positive rate was the highest in Beigang River among the three rivers, especially on organophosphates (the highest was acephate at 9.5 μg/L). The detected concentrations were associated with the used amount of pesticide active ingredients. Concentrations of analytes in the samples from the sewage treatment plant, the drinking water treatment plant, the reservoir, and the samples from the NIEA were either lower than the limit of quantitation (500 ng/L) or not detectable.

Pesticides;LC-MS/MS;drinking water;Surface water;Solid-phase extraction