Chiew Mei Chong1, Hans-Joachim Hübschmann2*

A fully automated QuEChERS extraction and extract clean-up method for GC-MS and LC-MS analysis is presented by using an industry standard robotic x,y,z-sampling system. The application describes the analysis of organophosphate pesticides from homogeneous liquid samples, as an example orange juice was used. The automated workflow includes the extraction with acetonitrile, salting out and using a µSPE cartridge for matrix clean-up prior to injection into a GC-MS/MS system. The method validation techniques such as pre-spike and post-spike were fully integrated into the automated workflow as well. Calibration linearities of the applied organophosphate pesticides in orange juice matrix range from 1 to 100 ng/mL with a precision achieved better than 0.995 for all compounds. By spiking 10 ng/mL of pesticides into the orange juice samples, recoveries were obtained in the of range 70% – 115%, while the precision from pre-spike (n=7) and post-spikes (n=6) under the same concentration was less than 10% RSD. The calculated method detection limits (MDLs) of the monitored pesticides were in the range of 1.8 ng/mL to 4.1 ng/mL which are well below the regulated maximum residue limits (MRLs) of 10 ng/g for these pesticides.

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