Rapid Determination of Dimethoate in Nanoliter of Juice Using Surface Desorption Atmospheric Pressure Chemical Ionization Mass Spectrometry

A rapid analytical method based on nanoliter-level sampling technique and surface desorption atmospheric pressure chemical ionization mass spectrometry (SDAPCI-MS) has been developed for the determination of trace dimethoate in juices without any sample preparation. The nanoliter-level juices were sampled by a home-made sampler equipped with a stainless steel sampling probe. The minimum sampling volume was suggested to be 0.11 nL. Based on the experimental results, the linear correlation between dimethoate signal and concentration was significant in the range of 0.001−10.0 mg kg−1 with the correlation coefficient (R) of 0.988. The recoveries were in the range of 80.5%–120.6%, and the detection limit of dimethoate was determined to be 1.2×10−11 mg kg−1.