Optimization and validation of in-situ derivatization and headspace solid-phase microextraction for gas chromatography–mass spectrometry analysis of 3-MCPD esters, 2-MCPD esters and glycidyl esters in edible oils via central composite design

• Published in: Food chemistry 2020-03, Vol.307, p.125542, Article 125542
• Main Authors: Xu, Minwei, Jin, Zhao, Yang, Zhongyu, Rao, Jiajia, Chen, Bingcan
• Format: Article
• Language: English
• Subjects: 2-MCPD esters; 3-MCPD esters; alpha-Chlorohydrin - chemistry; Central composite design; Edible oil; Esters - analysis; Esters - chemistry; Fatty Acids - chemistry; Food Contamination - analysis; Gas Chromatography-Mass Spectrometry; Glycerol - analogs & derivatives; Glycerol - chemistry; Glycidyl esters; Limit of Detection; Plant Oils - chemistry; Solid Phase Microextraction - methods; Solid-phase microextraction
• ISSN: 0308-8146; 1873-7072
• DOI: 10.1016/j.foodchem.2019.125542

•Monitoring MCPD esters and glycidyl esters with HS–SPME–GC–MS instead of liquid injection–GC–MS.•Derivatization, derivatives extraction and desorption with automated equipment.•Employing PBS in the derivatization system for the protection of the SPME fiber.•Screening parameters of SPME fiber with DSD prior to optimization with CCD.•Alkaline hydrolysis is less stable than acidic hydrolysis of MCPD esters. This study aimed to develop a headspace solid-phase microextraction gas chromatography–mass spectrometry (HS–SPME–GC–MS) method for the quantification of 3-monochloropropane-1,2-diol fatty acid esters (3-MCPDEs) and 2-monochloropropane-1,3-diol fatty acid esters (2-MCPDEs), and semi-quantification of glycidyl fatty acid esters (GEs) in edible oils. A central composite design was implemented to optimize the derivatization temperature and extraction time, which were 100 °C and 80 min, respectively. HS–SPME coupled with in-situ derivatization was more straightforward (three steps) and sensitive, with a limit of detection of 16% (3.9 µg/L) and 11% (5.3 µg/L) higher than that of liquid injection method, for 3-MCPD and 2-MCPD, respectively. The recoveries of 3-MCPD and 2-MCPD were in the range of 91.1% to 102.1%, with a relative standard deviation ranging from 0.08 to 9.29%. The validated methodology was successfully applied to oil samples. Further efforts will focus on shortening the extraction time, as 80 min is relatively long.