Determination of neonicotinoid insecticides in natural waters by high-resolution time-of-flight mass spectrometry with direct electrospray ionization of samples

A possibility of the direct electrospray ionization of seven neonicotinoids (acetamiprid, dinotefuran, imidacloprid, chlothianidin, nitenpyram, thiacloprid, and thiamethoxam) and their determination in natural waters by quadrupol high-resolution time-of-flight mass spectrometry is shown. A considerable matrix effect in the determination of neonicotinoids in natural waters was found. It was eliminated by the tenfold dilution of test samples with deionized water. Two versions of the determination of neonicotinoids in natural water samples are proposed: the method of standard additions and the method of calibration graph constructed for solutions in deionized water in the analysis of samples tenfold diluted with deionized water. The analytical ranges for neonicotinoids are 1-50 ng/mL. The relative standard deviation of the results of analysis does not exceed 12%; the duration of analysis is 10-15 min.