3.4 Feasibility Study
3.4.1 Standard curve, regression equation and detection limit
The 3-MCPD standard solution was used for derivatization to make the standard curve, and then the sample was spiked with the standard solution to determine the content of 3-MCPD ester in edible oil. Due to the esterification reaction of 3-MCPD to free 3-MCPD, the structure characteristics of 3-MCPD itself lead to the shortcomings of the chromatographic peak width and low sensitivity in the direct determination of 3-MCPD, so the test will be further derivatization of 3-MCPD[15].
The 3-MCPD standard solution of 10, 50, 100, 200, 400 ug was diluted with the prepared standard stock solution,operate according to the steps of 2.4 adding derivatization reagent (PBA), and test according to the GC-MS Analysis conditions of 2.6. The standard curve was drawn with the amount of 3-MCPD (X) as abscissa and the peak area (Y) as ordinate. At the same time, 3 times SNR was used to determine the minimum detection limit. Standard curve of 3-MCPD is showed in Fig.8. The linear range, regression equation, correlation coefficient and detection limit of this method are shown in Table 2.
3.4.2 Precision and recovery rate
Three levels of 3-MCPD ester recovery experiments were carried out with vegetable oil as substrate, Repeat six times for each spiked level. Under the optimal enzymatic hydrolysis conditions, the recovery of 3-MCPD was 92.1%-101.4%, the relative standard deviation (RSD) of 3-MCPD ester was 3.8%-4.3%, the results are shown in Table 3. According to the regression equation, detection limit, recovery rate and other methodological parameters, The method has the characteristics of high sensitivity, good specificity and high precision for the determination of 3-MCPD esters in vegetable oil. It can satisfy the purpose of determining the total 3-MCPD esters in vegetable oil.