Determination of Five Illegal Additives in Wheat Flour by Liquid Chromatography-Tandem Mass Spectrometry
A liquid chromatography-tandem mass spectrometry analytical method was established for the rapid determination of five kinds of illegal additives in wheat flour.The samples were extracted with primary water on an Agilent Eclipse Plus C18 column with 0.1%formic acid+10 mmol·L-1 formic acid amine solution and methanol as the mobile phase by gradient elution.The five illegal additives were qualitatively and quantitatively detected by electrospray ionization in positive and negative ion scanning mode.The results of the five compounds showed good linear relationship(r was greater than 0.999 0)in their respective linear ranges.The limits of detection and limits of quantitation of thiourea,kojic acid,and hypophosphite were 25 μg·kg-1 and 50 μg·kg-1 respectively.The limits of detection and limits of quantitation of trisodium thiocyanate and benzohydroxamic acid were 5 μg·kg-1 and 10 μg·kg-1 respectively.Average recoveries of three spiked levels were in the range from 82.1%to 101.0%,and the RSD were between 0.8%and 5.8%(n=6).This method has good specificity,high sensitivity,simple and fast pre-treatment,and can be used for rapid screening and quantitative determination of thiourea,kojic acid,hypophosphite,benzohydroxamic acid,and trisodium thiocyanate in wheat flour.