Study On The Determination Method Of Lead Chrome Green In Tea

Lead chrome green is a kind of industrial pigment which is illegal used to dye the food by some enterprises. The main elements are lead and chromium. If lead and chromium overweight in food, it will cause great damage to the human central nervous system, liver, kidney and other organs, and also will lead to a variety of lesions.Lead chrome green is a mixture composed of lead chrome yellow and iron blue or phthalocyanine blue spell color pigment. It is currently not from a particular chemical substance content up to lead chrome green qualitative and quantitative, so there is no national standard test methods.Because of phthalocyanine blue is the only possible organic matter in lead chrome green,and lead chrome yellow is the container in lead chrome green, the research to the level of phthalocyanine blue or lead chrome yellow content can be to the level of characterization of lead chrome green content, content of lead chrome green in the specimen with phthalocyanine blue or lead chrome yellow.At present, the illegal application of lead chrome green in food is mainly found in the tea, so this study chose tea as the research object,establish a complete detection method to determine the lead chrome green tea in the tea. Its main contents are as follows:1. Summary of the current status of industrial dyes in food and harm to consumers. After comparing with the commonly used method in the literature, the paper illustrates the innovation and necessity of the research on the instrumental analysis method of lead chrome green in tea.2. Under the optimized experimental conditions, the method of gas chromatography- mass spectrometry(GC-MS/MS) was established forthe determination of phthalocyanine blue in tea. At room temperature,ultrasonic tea with cold water elution sample of phthalocyanine blue and the multiple eluting extracts were combined and heating concentrated to nearly dry, add nitric acid digestion, the ethyl acetate extract in the digestion solution of phthalimide, by gas phase chromatography- tandem mass spectrometry determination of content of phthalimide and to calculate the content of phthalocyanine blue in the sample. And the effect of matrix on the detection limit and recovery rate of phthalocyanine blue was determined by the addition of the blank. The recovery rate is only48.8%~70.1%, and the accuracy of the method is not satisfied with the analysis requirements.3. Under the optimized experimental conditions, the gas chromatography isotope dilution mass spectrometry method was established for the determination of phthalocyanine blue in tea. In the determination of the content of the phthalocyanine blue in the sample, the content of the phthalocyanine blue in the solution was determined by the phthalimide-d4, and the content of the phthalimide in the solution of phthalocyanine blue was determined in the range of the mass concentration of two. The method is accurate, feasible and sensitive, and is suitable for the determination and confirmation of phthalocyanine blue in tea. Method recovery rate was 74.8%~86.4%, and the relative standard deviation was 3.9%~4.6%.4. Under the optimized experimental conditions, the inductively coupled plasma atomic emission spectrometry method was established for the detection of lead chrome green in tea. With cold water ultrasonic elution in tea samples of lead chrome green, multiple eluting after the extract was combined, heating concentrated to near dryness, adding mixed acid digestion, by inductively coupled plasma optical emission spectrometry(ICP-OES) content determination of Pb and Cr in thedigestion solution are calculated, and then the content of lead chrome green in the sample. Method the recovery rate was above 90%, and the relative standard deviation was 0.9%~1.8%.