Development of the Microwave-Assisted Extraction and Dispersive Liquid–Liquid Microextraction Method for the Analysis of Phytosterols in Cheese by Gas Chromatography Mass Spectrometry

In this investigation, an innovative, uncomplicated, swift, and effective technique based on microwave-assisted extraction (MAE) and dispersive liquid-liquid microextraction (DLLME) ensued by gas chromatography mass spectrometry (GC-MS) was formulated to determine the quantity of 4 phytosterols compounds in cheese samples. Under optimum circumstances for the process of Microwave-Assisted Extraction (MAE), a cheese sample weighing 0.2 g was subjected to extraction through employment of a closed-vessel system comprising of 5 mL of 2 M KOH and ethanol in a proportion of 70:30. The extraction procedure for phytosterols from a solution was executed through the utilization of 500 µL chloroform and a centrifugation lasting 5 minutes that was conducted at a velocity of 5000 rpm. Following this, the phytosterols underwent derivatization to generate their trimethylsilyl (TMS) derivatives, post which their analysis was carried out via GC-MS. Satisfactory outcomes were achieved through the implementation of this technique. The devised approach demonstrated favorable repeatability, exhibiting a relative standard deviation ranging between 4% and 8%, alongside exceptional enrichment factors, spanning from 162 to 180 for 4 phytosterols, in the spiked cheese sample. The present study has determined the limits of detection and quantification for all target phytosterols to be within the range of 0.12–0.32 and 0.45–0.71ng/g, respectively. The present study has observed linear Calibration curves within the range of 0.3-100 ng g−1, exhibiting correlation coefficients(R2) that varied from 0.993 to 0.997. The recoveries of the target analytes in cheese were exceptional, spanning a range of 95% to 99%.