A standard solution mixture of about 1ppm concentration was prepared and injected using Programmable Temperature Vaporization (PTV) technique to determine precursor ions for individual pesticides in Q3 scan mode. The GCMS-TQ8030 was set to Ultrafast Scanning (UF Scanning) mode and with Automated Scan Speed Protocol (ASSP)TM function on for the analysis. Further product ion scan was taken for individual pesticide from the standard mixture followed by appropriate optimization of collision energy to obtain their characteristic MRM transitions. The cross talk was eliminated because of Ultra Fast Sweeping Technology (UF Sweeper).
After optimizing MRM transitions for each pesticide, a mixture of 100 pesticides was analysed in a single run. Experiment was planned accordingly to carry out extraction of pesticides in the salad, in pre-cooked and post-cooked conditions. The recovery studies were carried out by spiking 100ppb mixture of pesticides and recovery was found to be within acceptable range. It was observed that the pesticide residues were considerably less in post-cooked salad as compared to pre-cooked.
Linearity of each pesticide for concentration levels ranging from 10ppb to 500ppb was having regression coefficient >0.99. The %RSD for six replicate injections of 100ppb concentration was found to be less than 5%.
The LOD values for individual pesticides were in the range of 0.1ppb to 3ppb. Similarly, the LOQ values were within the range of 0.5ppb to 10ppb.