Pesticides have been used widely on crops, inhibition of weed growth, and pest control. Pesticides and their metabolites may enter the water environment through runoff or air deposition, and their impact on human health and aquatic creatures deserve attentions.
This study developed and validated a method to analyze 102 pesticides using high-flow solid-phase extraction and ultra-high performance liquid chromatography/tandem mass spectrometry (UPLC-MS/MS). Analytes included 62 insecticides, 8 fungicides, 28 herbicides, 1 acaricides, 1 nematocides and two others, which were acephate、azinphos-methyl、bromophos-ethyl、carbophenothion、chlorpyrifos、demeton、demeton-S-methyl、diazinon、dichlorvos、dicrotophos、dimethoate、disulfoton、EPN、ethoprophos、fenamiphos sulfoxide、fenamiphos sulfone、fenitrothion、fenthion、fonofos、isoxathion、malathion、methamidophos、methidathion、mevinphos、monocrotophos、oxydemeton-methyl、parathion、phenthoate、phorate、phosalone、phosmet、pirimiphos-methyl、profenofos、quinalphos、temephos、terbufos、triazophos、trichlorfon、aldicarb、aldicarb sulfoxide、aldicarb sulfone、benfuracarb、carbaryl、cartap、carbofuran、3-hydroxycarbofuran、carbosulfan、ethiofencarb、fenobucarb、isoprocarb、methiocarb、methomyl、oxamyl、pirimicarb、propoxur、thiofanox、cypermethrin、deltamethrin、fenpropathrin、fenvalerate、permethrin、tau-fluvalinate、carbendazim、edifenphos、hexaconazole、iprobenfos、metalaxyl、pencycuron、prochloraz、thiophanate-methyl、2,4-D、2,4-DB、2,4,5-T、2,4,5-TP(Silvex) alachlor、atrazine、atrazine-desethyl、atrazine-desethyl-desisoropyl、atrazine-desisoropyl、butachlor、cyanazine、dalapon、dicamba、dichloroprop、dinoseb、diquat、diuron、glufosinate、isoproturon、linuron、MCPA、MCPP、mefenacet、metolachor、molinate、pendimethalin、propazine、simazine、ethion、ethoprop、chloral hydrate、quinoline.
500-mL of water was extracted with PolarPlus C18 speeddisk (50 mm) and was eluted with methanol and dichloromethane. The combined eluent was concentrated to 5 mL and was analyzed with the UPLC-MS/MS. Analytes forming positive ions were separated on a Kinetex PFP column (50 × 2.1 mm, 2.6 μm), and chemicals forming negative ions were done on an Ascentis Express C18 column (50 × 2.1 mm, 2.7 μm). The method has been developed and validated through analyzing spiked raw water samples and certified reference materials. Most analytes were with recoveries ranged from 63% to 114%.
To demonstrate the feasibility to various types of water, samples were collected from three rivers in southern Taiwan (Beigang River, Bajhang River, and Yanshuei River), a reservoir as a drinking water source, raw water and finish water from a drinking water treatment plant, and influent/effluent from a sewage treatment plant, in the total of 35 samples. Among the river water, most positive samples of pesticide residues were found from Beigang River, especially at the sampling point of Hou-Liao Village (the highest was carbendazim at 8.7 μg/L). Most analytes were either not detected or with levels lower than the limit of quantitation (0.5 μg/L) in the samples of reservoir, drinking water treatment plant, and the sewage treatment plants; however, a herbicide pendimethalin was in relatively high concentrations in the samples of sewage treatment plants (0.91.6 μg/L), and was also detectable in the samples of the reservoir and the drinking water treatment plant. The positive rates of pesticides were associated with their used amount of active ingredients.