Abstract: A rapid method for the trace level detection of ametryn and atrazine residues in food matrices was developed by using a selective ambient mass spectrometry (AMS) ion source based on molecularly imprinted polymer modified iron sheet (MIPIS) in combination with electrospray ionization mass spectrometry (ESI-MS). Molecularly imprinted polymer (MIP) using cyanazine as template molecule was prepared by polymerization of methacrylic acid (MAA) and aniline in aqueous solution. MIPIS was used as an extraction tip for rapid enrichment of ametryn and atrazine in soy milk powder, wheat and milk before direct analysis by AMS ion source coupled to ESI-MS. The results showed that the linearity of this method ranged from 0.2 to 200 μg/L, with correlation coefficients of 0.998 2 and 0.999 7 for ametryn and atrazine, respectively. The average recoveries of ametryn and atrazine at three spiked levels ranged from 81.05% to 109.66%. The limits of detection (LODs) and the limits of quantification (LOQs) of the analytes were 0.2–0.5 μg/kg and 0.6–1.5 μg/kg, respectively. This study has provided a simple and sensitive method that can effectively avoid the tedious sample pretreatment and time-consuming chromatographic separation for rapid detection of trace levels of triazine pesticide residues in foods.

Key words: ametryn; atrazine; molecularly imprinted polymer; ambient mass spectrometry ion source; electrospray ionization mass spectrometry