Matrix Effects In Determination Of Multiresidues Of Pesticides In Vegetables Using Gas Chromatography/mass Spectrometry

In this paper, 29 pesticides in 17 sorts of vegetable matrices were collected for the study of matrix effects by GC-MS. In order to illuminate the courses and factors of matrix effects, the differences of matrix effects of different sorts and concentrations of matrices and pesticides,number and type of active sites in the inlet and GC column,inlet temperature, injection technique and volume were compared .At the same time, the capabilities to eliminate matrix components of different clean-up methods and the analyte protectants compensation for matrix effects were evaluted. The main results were showed as follow.1.The active sites in the inlet and GC column are essential causes which lead to matrix effects, those active sites exist originally and produced by contaminations are involved.2. matrices with complicated components such as green pepper and mushroom produce higher matrix effect; Lotus root without obvious matrix effect; higher concentration of matrix can produces higher matrix effect; Some terpenes and ramifications of aromatic components can produce matrix effects probably3. except for some organophosphoros pesticides(methamidophos, acephate,omethoate, monocrotophos, triazophos and azinphos-methyl) ,some zole pesticides (triflumizole, flusilazole, paclobutrazol)and some crudes such as azoxytrobin are much easier affected with matrix effect; pesticides with lower concentration produce lower matrix effect.4.To adjust the instrument and let it at its best or use appropriate injection technology ,such as available maintenance of inlet and GC column, improveing the temperature of inlet,injection with pulsed splitless and using larger injection volumn.5.Some susceptive pesticides can get better peak shape and higher sensitivity with An-alyte protectants,that means the analyte protectants can compensate matrix effect very we-ll.