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A method for the quantification of 1,3-dioleyl-2-palmitoyl-glycerol (OPO) in infant formula was developed. The samples were treated with ammonia and extracted with organic solvents. The fat containing OPO was purified on a NH2 solid-phase extraction (SPE) cartridge packed with aminopropyl as the sorbent. The eluate was separated by silver ion chromatography using 0.55% acetonitrile-hexane as the mobile phase. The detection was carried out with a high performance liquid chromatography-evaporative light scattering detector (HPLC-ELSD). This novel procedure enabled the complete separation of OPO and its isomer 1,2-dioleyl-3-palmitoyl-glycerol (OOP), thus allowing for the accurate quantification of OPO. The developed method showed the desired linearity in the concentration range of 25–500 μg/mL with a determination coefficient (R2) of 0.999 6. The limits of detection (LOD) and limits of quantification (LOQ) were 0.30 and 0.90 g/kg, respectively. At spiked concentrations from 1 to 96 g/kg, the average recoveries of OPO varied from 97.1% to 104.2% with relative standard deviations (RSD) between 1.2% and 2.9%. The precision and accuracy of this method met the relevant requirements, and it passed the inter-laboratory collaborative validation. Our investigation analyzed 39 commercial samples of OPO-fortified infant formula in China, revealing that the measured OPO content only accounted for 28.4% to 59.7% of the labelled value, which is mainly due to the inconsistency of detection methods.

ObjectiveAn online fully automated alkaline hydrolysis method for the determination of chloropropanol esters （MCPDE） and glycidyl esters （GE） in edible oils and fats was developed， and the effects of vegetable oil type and temperature on the conversion of GE to 3-chloro-1，2-propanediol （3-MCPD） were investigated.MethodsBased on the basic principles of AOCS Cd 29c-13， the samples were subjected to hydrolysis， chlorination， liquid-liquid extraction and derivatization on a fully automated sample pretreatment platform， and then separated by a DB-5MS column after injection. The data was determined by multiple reaction monitoring mode （MRM） coupled with the internal standard method.ResultsThe efficiency of GE conversion to 3-MCPDE in the five vegetable oils was significant different. However， the effect of temperature was relatively greater. The alkali hydrolysis time was optimized， and the hydrolysis of MCPDE and GE was basically completed when the hydrolysis was carried out for 7 min at 10℃. The limits of detection for 2-chloro-1，3-propanediol （2-MCPDE）， 3-chloro-1，2-propanediol （3-MCPDE） and GE were all 5 μg/kg calculated by their free forms. There was a good linear relationship between the concentration and ratio of the response ranged from 0 to 0.4 μg/mL. When spiked from 20 to 2 500 μg/kg， the recoveries of MCPDE and GE ranged from 90.3% to 109.7% with the relative standard deviation （n=6） of 1.3%-7.7%， indicating that the precision was better than that of the manual procedure. The method was comparable with the Chinese national standard method for food safety under reviewed and was successfully applied to the determination of FAPAS proficiency test samples.ConclusionThe novel automatic procedure has the advantages of simple operation and high sensitivity， which reduces the labor intensity， improves the detection efficiency and repeatability compared with the reported manual procedure， and can better meet the requirement for quantification of MCPDE and GE in edible oils and fats.

Fatty acid esters of chloropropanediols are a kinds of newly emerged food contaminants, especially 3-monochloropropane-1,2-diol (3-MCPD) esters that have been detected in many foodstuffs such as infant formula and edible oils at relatively high levels. Based on the Tolerable Dose Intake (TDI) of 3-MCPD, the intake of 3-MCPD from 3-MCPD esters may cause the health risk to human beings. The researches for the analysis of 3-MCPD esters have been carried out in some institutes abroad, but there were only a few in China. This paper reviews the methods for the determination of 3-MCPD esters in fat-rich foods, including the extraction, hydrolysis, the derivatization of 3-MCPD esters, the total amount of 3-MCPD esters and the amounts of monoesters and diesters of 3-MCPD.