Rapid determination of two monochloropropanediols in milk powder by Gas Chromatography-Mass Spectrometry
A gas chromatography-mass spectrometry method was established for simultaneous determination of 3-chloro-1,2-propanediol(3-MCPD)and 2-chloro-1,3-propanediol(2-MCPD)in milk powder.After the sample was extracted with methanol and concentrated,the extract was reconstituted by adding 20％sodium chloride solution.After degreasing with n-hexane,no further purification was required.Then the target compound was extracted with ethyl acetate,and phenylboronic acid was added as a derivatization reagent.After concentration,the derivative of the target compound was separated by DB-5MS hromatographic column(30 m × 0.25 mm × 0.25 μm),detected by selective ion monitoring mode(SIM)and internal standard method for quantification.The results shows that the method had good linearity in the range of 0-400 pg/L,and the correlation coefficients(r2)were all greater than 0.999.The limit of detection(LODs)was 0.002 mg/kg,and the limit of quantification(LOQs)was 0.005 mg/kg for both 3-MCPD and 2-MCPD.The average recoveries were 96.3％-103.8％at three concentration levels of the quantification,the limit of quantification of 3-MCPD and in between,and the relative standard deviation(RSD)was 0.19％-8.36％.The method was easy to op-erate,low in cost,good in sensitivity and high in accuracy,and can provided technical support for risk monitoring of milk powder.
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