Optimization of Headspace Single-Drop Microextraction Coupled with Gas Chromatography-Mass Spectrometry for Determining Volatile Oxidation Compounds in Mayonnaise by Response Surface Methodology

In this assay, headspace single-drop microextraction (HS-SDME) coupled with gas chromatography-mass spectrometry (GC-MS) as a simple, low-cost and rapid method has been developed and validated for determining volatile oxidation compounds including hexanal and heptanal in mayonnaise. The main microextraction variables affecting the HS-SDME procedure such as extraction temperature and time, stirring rate, and amount of NaCl were optimized by response surface methodology employing a central composite design. Obtained results demonstrated that higher yield of extracted analytes could be achieved under the following optimal conditions: extraction temperature of 45 A degrees C, extraction time of 16 min, stirring rate at 700 rpm, and addition of 2 g NaCl. The optimized HS-SDME/GC-MS method was validated for oxidized mayonnaise samples (50 A degrees C/48 h) by calculating analytical parameters (linearity, precision, accuracy, and sensitivity). Good linearity (R (2) > 0.99) was observed by plotting calibration curves of extracted hexanal and heptanal over the concentration range of 0.025-10 mu g g(-1), and the repeatability of the method, expressed as relative standard deviation, were found to be 4.04 % for hexanal and 3.68 % for heptanal (n = 7). After the microextraction process of spiked mayonnaise sample, high levels of relative recovery were obtained for hexanal (107.33 %) and heptanal (91.43 %). The detection limits were 0.008 ng g(-1) and 0.021 ng g(-1) for hexanal and heptanal, respectively, while quantification limits of hexanal and heptanal were calculated to be 0.027 ng g(-1) and 0.071 ng g(-1), respectively. The possibility of the HS-SDME followed GC-MS to determine and quantify volatile oxidation compounds such as hexanal and heptanal was confirmed by analyzing commercial fresh mayonnaise stored at 4 and 25 A degrees C during 3 months.