Determination Of Fatty Acid Esters Of Chloropropanols In Edible Oil And Structured Fat In Infant Formula

As the nutrition additives in Infant formula, 1,3-dioleoyl-2-palmitoyl-glycerol (OPO) and chemical contaminants in food, fatty acid esters of chloropropanols (MCPD esters) have been concerned worldwidely.The advance of methods for quantifying these compounds was reviewed(see Chapter 1). Two analytical methods were developed and the relevant factors were optimized. Methodological indicators were investigated and this methord was applied to the determination of actual samples. The determination method of OPO has realized the complete separation of isomers; The determination method of MCPD esters was fully validated by attending FAPAS proficiency test worldwide for MCPD esters, and the results by two methods (acid hydrolysis and alkaline hydrolysis) were statistically analyzed and compared; the establishment of the instrument conditions has Completed for the determination of monomer and it can complete analysis of 20 kinds of monomers One-time.1) Development of the analytical method for the determination of the OPO in Infant formula (see Chapter 1)Methods:An analytical method was developed for the determination of OPO in Infant formula by High performance liquid chromatography (HPLC) - evaporative light scattering detector. The conditions of Chromatographic column types, mobile phase type、composition、 ratio、flow rate, column temperature, detector parameters etc were optimized. Result:Under the optimized condition, the detection limit (LOD,S/N=3) were 0.35g/kg and the quantification limit (LOQ,S/N=10) were 1.2g/kg. When OPO was spiked at levels ofl.25～ 12.5 g/kg to infant formula, the average recoveries were 82.8～117%,and relative standard deviation (RSD) were 2.77～9.34 (n=6). This method is of high accuracy and good precision and the indicators meet the testing requirements.2) Development of the analytical method for the determination of the MCPD esters in edible oil (see Chapter 2)Methods:An analytical method was developed for the determination of 2-MCPD esters and 3-MCPD esters in fat-rich foods by acid hydrolysis coupled with gas chromatography-mass spectrometry. The conditions of solid phase extract were optimized. Such condition as type、concentration of acid, method、temperature、time of hydrolysis and types of dehydrating agent were optimized. Result:Under the optimized condition, the detection limit (LOD,S/N=3) were 2.5-10μg/kg and the quantification limit (LOQ,S/N=10) were 8.0-33μg/kg. According to the internal standard calibration, an excellent linearity between 25 and 1000 ng of MCPD esters (R>0.9990) was obtained. When MCPD esters was spiked at levels of 0.25-1.0 mg/kg to edible oil, the average recoveries were 76.7～106%, and relative standard deviation (RSD) were 2.73-9.55 (n=6). This method is of high accuracy and good precision and the indicators meet the testing requirements. There was significant correlation between the methord of acid hydrolysis and alkaline hydrolysis (R>0.95).3) Development of the analytical method for the determination of the MCPD ester monomer in edible oil (see Chapter 3)Methods:An analytical method was developed for the determination of 20 MCPD ester monomers in edible oil by High performance liquid chromatography - mass spectrometry method coupled with multiple reaction monitoring (MRM) mode and chemical ionization (ESI) source and positive ion mode (ESI+). Such condition as mobile phase composition and proportion, and type of chromatographic column as well as the needle washing liquid composition and volume were optimized. Result:The instrument detection limit (LOD) were 0.2-5.0ng/mL,and the instrument quantification limit (LOQ) were 0.6-15ng/mL. According to the external standard calibration, an excellent linearity between 1.0 and 50ng/mL of MCPD ester monomers (R are between 0.9923 to 0.9999) was obtained. The methord was Preliminary used for edible oil for the matrix effect check, and found that the substrate effect is relatively serious, so further optimize for the sample preparation step is needed.