Investigation of sample preparation teqniques for chromatographic analysis of fatty matrices

Pesticides are efficient in controlling weeds and pets during planting however; their residue in food should be monitored for safety of the food. Traditional analysis methods are complicated and labor-intensive and fatty foods are particularly challenging. In this thesis, determination of pesticide residues in black olive samples by Liquid chromatography tandem mass spectrometry (LC-MS/MS) method was investigated. Considering the fatty matrix of the black olives, QuEChERS method which stands for the quick, easy, cheap, efficient, rugged and safe method was chosen. In the first part of the study, original method was applied to the black olive samples and pesticide residues for 46 active ingredients were quantified according to their chromatographic peak areas. The calibration graphs were drawn in ppb ranges. In the second part of the thesis, some modifications were made to the original method to improve the d-SPE clean up step and MgSO4 was replaced with CaCO3 for the first time where tert-butyl ammine (TBA) was used instead of PSA. In order to reveal the effect of the amount of these sorbents on the recovery values along with the C18 used in dSPE step, full factorial experimental design was applied at two levels. Recovery studies have been performed at two concentration levels and the results have been compared with those of original QuEChERS method. Overall results have demonstrated that recovery values were distributed in a wide range and were found out of the 70-120% range for the 8 experiments in the design. One of the reasons to this outcome is the pesticides studied display a wide range of polarity and hydrophobicity due to the structural differences. Another reason is that CaCO3 is not hygroscopic as MgSO4 used in QuEChERS method.