Development and validation of a purge & trap- thermal desorption- gas chromatography- mass spectrometry method for the determination of propylene chlorohydrins (PCH) in hydroxypropyl starch and/or propylene oxide fumigated food products.

摘要

Propylene oxide has been widely used in food industry to modify food functionality and to sterilize food products. Examples include hydroxypropylation of starch and cellulose to modify cold water solubility and sterilization of nutmeat like almonds. In this process, some undesirable side chemicals such as PCH are produced. PCH are mutagens and potential carcinogens. The level of PCH permissible in modified starch is regulated internationally. Food Chemical Codex, Joint FAO/WHO Expert Committee on Food Additives (JECFA) and European Commission on food additives have set the limit of PCH in hydroxypropyl starch, which is less than 1mg/kg. However, because few toxicology guideline studies are available on PCH, the hazardous effects have not been fully understood and the allowable residue content of PCH in many food products has not been specified by regulations.;Recent independent studies conducted in the US and Europe have suggested that the certified international method for PCH quantification in modified starch may underestimate the amount of residual PCH. The objective of this research is to develop an alternate method for PCH quantification and to independently evaluate the results of a newly proposed solvent extraction GC-MS analytical method (AVEBE unpublished study).;The P&T-TD-GC-MS method includes four steps: solvent extraction with water or MEOH, Purge & Trap concentration, thermal desorption and GC-MS analysis. It incorporates 3-chloro-1-propanol (a PCH structural isomer) as a matrix-spiked internal standard. The method is approximately 100 times more sensitive than the proposed European solvent extraction-GC-MS method, allowing for full-scan mass confirmation in contrast to the European method that uses selected ion monitoring. The P&T-TD-GC-MS method also eliminated the requirement of a highly specific GC injector (Programmed Thermal Volatilizer or PTV) which is mandated by the European method and not commonly available to most labs.;With this P&T-TD-GC-MS method, the LOD of both PCH1 and PCH2 is 0.025mg/kg and their LOQ is 0.1 mg/kg. A series of method validation tests, including precision, system suitability and recovery were conducted to determine the accuracy and sensitivity of the P&T-TD-GC-MS method in this study.