| A new method for rapid determination of multiclass pesticides in meat usingonline gel permeation chromatography coupled with multidimensional gaschromatography/mass spectrum (GPC-MDGC/MS) was developed and validated.One positive aspect of the online GPC–MDGC/MS instrument for themulti-residue determination of pesticides in complex matrices is a substantialsimplification of purification achieved by combining sample purification device GPCtogether with analytical instruments. Online GPC can remove some macromolecules(such as lipids, proteins, pigment and polymer) and the whole process took only tenminutes, bringing a cutback of time, labor force and solvent amount substantially.Another advantage is multi-purification capacity and powerful separationperformance. With the use of MDGC, analytes received further separation from smallmolecule matrix following GPC and solved the problem of overlapping peaks bymeans of heart-cutting selectively.280μL solvent pumped to the large volumeinjection system from GPC was released successfully by means of the open-timecalculation of solvent-vent switch based on the equation of state of ideal gas. In viewof the cold spray modulator of comprehensive two-dimensional gas chromatography,the low-temperature re-concentration improved sensitivity and accuracy in thechapiter of the second gas chromatography (2ndGC).Taking crucian as an example, high correlation coefficients (R2>0.99) wereobtained for the tested range. The limits of detection (LODs) were ranged from0.5ug/kg to2.0ug/kg and the limits of qualification (LOQs) were ranged from1.7ug/kgto6.7ug/kg. The recoveries of all analytes in crucian at three spiked level (0.01,0.05and0.1mg/kg for ethoprophos, tefluthrin, dimethoate and fenitrothion;0.03,0.15and0.3mg/kg for other pesticides) were within the range from83.0%to112.9%, withrelative standard deviation (RSD) generally less than12%(n=6).Finally, the design of experiment was discussed in temperature programmingoptimization of16pesticides. The result of orthogonal experimental design withfewer trials was consistent with point-by-point method. The conclusion thatthe orthogonal experiment design was efficient and reliable can be drawn. |
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