Qualitative And Quantitative Techniques For Determining The Banned Acid Dye In Raisin And Medlar

As the one of synthetic pigments, acid dye could cause disease and cancer because of the reduction of its azo group-aromatic-amine conjugate system which could combine with human cells and change the structure of the DNA. It will contaminat food lead to safety troubles when it was added to the food. So it has been forbidden in food all over the world and detection of acid dye is very important to the food safety and the consumer’s health.There are two types of detection methods about acid dye: the traditional methods(including layer chromatography, spectrophotometry, polarography and voltammetry) and the modern methods(including fluorescence spectroscopy, gas chromatography-mass spectrometry, HPLC and HPLC-MS/MS). Recently, detection of single acid dye was reported in many literatures while less reports about detecting multi-component acid dyes simultaneously. In this work the banned acid dyes were detected by UPLC, HPLC-MS/MS and IR raisin and medlar for affording references to exploring the qualitative and quantitative technology for banned acid dyes in raisin and medlar. The main contents as follows:(1) Under certain conditions, 23 kinds of acid dyes were detected in standard samples and mixing standard samples by UPLC and they could be divided into two groups based on the chromatographic separation. Separation conditions in UPLC were studied. Then the actual samples of raisin and medlar(extracted acid dyes) were pretreated and detected by UPLC at the same condition, using external standard method for quantitative analysis. The results showed that under optimum condition, the recovery was in the range of 85.2% ~104.8%, RSD was ≤ 6.42%, correlation index r ≧ 0.9905 and the LOD was 0.06~0.98 μg/g(S/N=3) for 23 kinds of acid dyes. Four kinds of raisins and a kind of medlar in market were pretreated and detected by UPLC. The results show that: Acid red 14, acid yellow 73 and acid yellow 11 were detected in A raisins; Acid red 1, acid red 14, acid yellow 73 and acid yellow 11 were detected in B raisins; Acid red 1 and acid red 14 were detected in C raisins; Acid red 1, acid yellow 73 and acid yellow 11 were detected in D raisins. Acid red 1 was detected in medlar; Other acid dye was detected.(2) HPLC-MS/MS analysis was used to detect 23 kinds of acid dyes standard samples and get the corresponding mass spectrum information. Under the optimized conditions, 23 kinds of acid dyes were detected in standard samples and mixing standard samples by HPLC-MS/MS and analyzed by external standard method. The results showed that under optimum condition, the recovery was in the range of 78.7%~101.3%, RSD ≤ 5.20%, correlation index r ≧0.9908 and the LOD was 0.05~0.26 μg/g(S/N=3)for 23 kinds of acid dyes. Four kinds of raisins and a kind of medlar in market were detected by HPLC-MS/MS and analyzed by external standard method. The results show that: Acid red 14, acid yellow 73, acid yellow 11,acid violet 43 and acid green 73 were detected in A raisins; Acid red 1, acid red 14, acid yellow 73, acid yellow 11,acid violet 43 and acid green 73 were detected in B raisins; Acid red 1, acid red 14 and acid violet 43 were detected in A raisins; Acid red 1, acid yellow 73 and acid yellow 11 were detected in D raisins; Acid red 1 was detected in medlar; Other acid dye was detected.(3) 23 kinds of acid dyes in standard samples(including acid black 1, acid orange 7, acid red 1, etc) and actual samples were tested by IR. The difference of characteristic absorption peak between them was compared and the qualitative identification of acid dyes was explored. Results indicated that the characteristic absorption peak of sulfonic group in 23 kinds of acid dyes exist each sample. It may be a basis for primary screening in acid dyes, which we studied in the paper.