Study Of Screening Colorants In Food By LC-TOF-MS

The abuse and illegal use of colorants in foods become an important issue of food safety.Due to the differences of color additives allowed used in different countries, the main testingmethods for food color additives are target test, while the screening method for contraband dyesand abused color additives was seldom reported. The screening method for36water-solublecolorants and19oil-soluble dyes in foods by Liquid Chromatography tandem Time of FlightMass Spectrum （LC-TOF-MS） was established in this paper. The separating capacity ofchromatogram and high resolution of mass spectrum was combined, database was establishedaccording to retention time、characteristic ion and exact mass. The established screeningmethod was applied to sample analysis, potential hazard to food safety can be forewarned andfood safety incidents can be prevented.The main contents in this thesis were as follows:1. The colorants used in food, the analytical methods for colorants in food and the usagestatus of LC-TOF-MS were summarized.2. Screening method for36water-soluble colorants was developed and applied based onLC-TOF-MS: suitable pretreatment was developed according to the compounds concerned inorder to maximize the extraction of colorants in food，chromatographic separation was achievedby using C₁8column with gradient mobile phase of methanol/water （V/V95/5） andwater/methanol （V/V95/5）consisting of5mmol/L ammonium formate respectively. TOF-MSwas optimized to acquire maximum response of36water-soluble colorants，database wasestablished according to retention time、 characteristic ion and exact mass. Correlationcoeffections of calibration curves were above0.91， average recoveries were between64.4%¹04.8%，relative standard deviations（RSD）were between2.2%¹3.0%。3. Screening method for19oil-soluble dyes was developed and applied based onLC-TOF-MS: extraction method was improved based on the standard method GB/T19681-2005.Chromatographic separation was achieved by using C₁8column with gradient mobile phase ofwater and acetonitrile consisting of0.1%formic acid respectively. TOF-MS was optimized toacquire maximum response of19oil-soluble dyes，database was established according toretention time、characteristic ion and exact mass. Correlation coeffections of calibration curveswere above0.98， average recoveries were between76.6¹05.8%， relative standarddeviations（RSD）were between1.3%¹1.4%。 4. Screening procedure using TOF-MS database applied to food samples from market，results shows that many kinds of water-soluble colorants were contained in foods，no illicit dyewas detected in food.