Determination of 11 Azo-dyes and Rhodamine B in Seasoning Oil by Gel Permeation Chromatography/Ultra Performance Liquid Chromatography with Electrospray Ionization Tandem Mass Spectrometry

KeyWord:gel permeation chromatography£¨GPC£©  ultra performance liquid chromatography-tandem mass spectrometry£¨UPLC-MS/MS£©  azo-dyes  rhodamine B  seasoning oil  determination

Abstract:

      An analytical method was developed for the simultaneous determination of 11 banned azo=dyes £¨Sudan red ¢ñ£¬Sudan red ¢ò£¬Sudan red ¢ó£¬Sudan red ¢ô£¬Sudan red 7B£¬Sudan red G£¬Sudan yellow£¬Sudan orange G£¬Sudan blue ¢ò£¬toluidine red£¬para red£© and rhodamine B in seasoning oil based on gel permeation chromatography followed by ultra performance liquid chromatography-tandem mass spectrometry£¨UPLC-MS/MS£©.The seasoning oil samples were extracted with cyclohexane-ethyl acetate£¨1¡Ã1£©£¬and then purified by gel permeation chromatography to remove the high molecular weight of interferences£¨e.g.fat£¬oil and natural pigments£©.Twelve target compounds were separated on an ACQUITY UPLC- BEH C18 column with 0.1% formic acid and acetonitrile as mobile phase by gradient elution£¬and detected by MS/MS under positive mode with multiple reaction monitoring£¨MRM£©.Good linearities for 12 dyes were achieved over the range of 1-50 ¦Ìg/L.The quantitation limits of 12 dyes in seasoning oil samples were in the range of 0.2-2.5 ¦Ìg/kg.The mean recoveries at three spiked level£¨5£¬20£¬40 ¦Ìg/L£© ranged from 54% to 125%£¬ with relative standard deviations£¨RSDs£© of 2.5%-17.2%.The method was used to analyze 35 seasoning oil samples taken randomly from the local market£¬and rhodamine B was found in 2 of the samples.The established method could be applied in the simultaneous extraction and purification of 11 azo-dyes and rhodamine B in seasoning oil matrix£¬and is suitable for the routine detection of illegally additive dyes in seasoning oil due to its simplicity and high sensitivity.