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

A method based on a nanoliter level sampling technique and desorption atmospheric pressure chemical ionization mass spectrometry(SDAPCI-MS) was developed for the rapid detection of trace dimethoate in juice without sample pretreatment. The precise sampling of untreated commercial juice samples was performed by using a homemade nanaoliter sampler( diameter of 80 mu m), which was made from a stainless steel needle. The minimum sampling volume was 0.11 nL. A good linearity of dimethoate signals was obtained in a range of 0.001 - 10.0 mg/kg with the correlation coefficient (R) of 0.988. The recoveries of real sample analysis were 80.5% - 120.6%. The detection limit of dimethoate was 1.2 x 10(-11) mg/kg for the juice sample.