[An automated direct immersion solid-phase micro extraction-gas chromatography-mass spectrometry (DI-SPME-GCMS) method for determination pesticides in liquid Chinese herbal health food].

OBJECTIVE: To establish a method to determinate 25 pesticides in liquid health food from Chinese herbal medicines by direct immersion solid phase micro extraction coupled with gas chromatography-mass spectrometry. METHODS: The sample was diluted with ultrapure water, adjusted p H with acetic acid, and then filtered by 0. 45µm filter. The target compounds were extracted and concentrated by the method of on-line immersion solid phase micro extraction( SPME) coupled with 65 µm PDMS/DVB extraction fiber. The sample was separated by GC-MS with TG-5 MS( 30 m × 0. 25 mm ×0. 25 µm) capillary column. RESULTS: The method showed a good linearity R2 above 0. 99 in the range of 20-200 µg/kg for 25 organic phosphorus pesticides analytes with average recovery rates of 77. 9%-97. 9%( n = 6) and the relative standard deviation( RSD)within 1. 72%-13. 57%. The limits of detection( LOD) were between 3-10 µg/kg. CONCLUSION: The method is simple, accurate, sensitive and very environmental friendly. It is suitable for the determination of 25 pesticides in liquid health food from Chinese herbal medicines.