Objective To develop a universal and more optimized examination method based on the national standard methods by consolidating and optimizing the current methods used for determination of dichlorvos, phorate, demeton, dimethoate, parathion-methyl, malathion, and parathion in three different kinds of water samples (drinking water, surface water, and industrial wastewater).
Methods Liquid-liquid extraction was used to pretreat water sampies and the instrumental parameters were optimized to achieve lower detection limits and lower determination limits. Qualitative and quantitative analyses were performed using enhanced gas chromatography-flame photometric detector (GC-FPD+) based on the suitability of the spike test confirmatory method for the three kinds of water.
Results Seven types of organophosphorus pesticides were completely separated within 15 min, showing a good linear relationship within the concentration range of (5~250) μg/L and determination limits of (0.01~0.03) μg/L. The spike and recovery rates were from 80.7% to 107.9% with relative standard deviations of less than 10% in the spike tests conducted using the three types of water samples.
Conclusion This method uses a small amount of samples and organic reagents during the pretreatment process for testing the three kinds of water samples. The determination limits of the seven types of organophosphorus pesticides are significantly lower than those of Standard examination methods for drinking water-Pesticides parameters(GB/T 5750. 9-2006) and Water quality-Determination of organic phosphorous pesticide in water-Gas chromatography(GB 13192-1991), with good resolution as well as high sensitivity, accuracy, and precision, while the qualitative and quantitative analyses of demeton involves the consideration of its two isomers. This method is suitable for examining seven organophosphorus pesticides in three different types of water.
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