GC-MS/MS Analysis of Pesticide Residue in Green Tea Extracted by QuEChERS with Acetonitrile as Final Solvent
Poster Jul 30, 2014
Cojocariu C., Morgan P., Silcock P., Godula M
This poster describes the analysis of several challenging pesticides from green tea samples using GC MS/MS and acetonitrile as final extraction solvent. The compounds analysed are representatives of various classes of pesticides, such as carboxamids, OC, OP, pyrethriods, aromatic, phenylamides. QuEChERS (Quick, Easy, Cheap, Effective, Rugged, Safe) is a well known approach used for the extraction and clean-up of pesticide residue in various matrices. Typically, the final extract ends up with the pesticides in acetonitrile. Direct injection of acetonitrile extracts is problematic in GC-MS compared to LC-MS because of poor focusing of chromatographic peaks due to the high polarity of acetonitrile, limitations on injection volumes due to the high expansion coefficient of acetonitrile and contamination of the system by matrix co-extractives .
Here we present a simple and robust analytical method which employs low volume splitless injections of acetonitrile sample extracts and the selectivity of the Thermo Scientific™ TSQ™ 8000 triple quadrupole GC-MS/MS instrument. With this approach, pesticide target reporting limits of <0.01 mg/kg can be easily achieved. This also overcomes the problems associated with the thermal expansion of acetonitrile and reduces the amount of matrix injected.