The Determination Of Mineral Elements In Honey By ICP-MS And Its Application To Discriminate Northeast-China Black Honey And Linden Honey

Northeast-China black honey enjoys the reputation of Product of Geographical Indication(PGI) in China, which is in rich of nutrition and commercial value. Because of the high price of PGI honey, the adulteration with low cost shoddy or mislabeling the origin of honey always occurs. This seriously undermined the legitimate rights and interests of consumers, affecting their confidence to buy. Thus, it is necessary to develope a reliable and accurate methodologies for the discrimination of PGI honey. In this study, the method for the determination of 23 mineral elements, such as B, Na, Mg, P, K, Ca, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, As, Rb, Sr, Mo, Cd, Ba, Pb and U has been developed by ICP-MS with microwave digestion and was applied to the Northeast-China black honey and linden honey. At the same time, the isotope ratios of Sr and Pb in them have also been determined. On the basis of the proposed method, chemometric methods were employed to develop classification models for the discrimination of Northeast-China black honey. The details could be found as follows:(1) The method for the determination of 23 mineral elements as well as the isotope ratios of Sr and Pb in honey samples has been developed by ICP-MS with microwave digestion. The spiking recovery was evaluated at three levels(n=6) with the results in the range of 86.5-109.8%. The standard substances, GBW10015 and GBW10016, were also determined and the obtained results of them were in the range of certified values. The results of repeatability and reproducibility could meet the analytical requirements. It's indicated that the developed method was accurate and rapid to determine mineral elements in honey samples with higher stability and reproducibility. It can be found that the contents of B,Na,Mg,P,K,Ca,Fe and Rb were higher than 1 mg/kg, while the contents for Mn,Zn,Ba,Sr,Ga and Cu were in the range of 10-1000 ?g/kg, and less than 10 ?g/kg for others. By comparison, the contents of mineral elements and the values of isotope ratios for Sr and Pb were different between Northeast-China black honey and linden honey.(2) The discrimination of Northeast-China black honey based on the contents of mineral elements. The results of ANNOVA showed that 8 mineral elements, Mg,Cr,Mn,Ni,Zn,Sr,Mo and Ba, had significant difference between Northeast-China black honey and linden honey. From the results of PCA, they could be clearly separated by the first component. The PLS-DA method was applied to construct the discrimination model and the performance was validated by model prediction and model training. As a result, Northeast-China black honey and linden honey samples could be classified correctly with both the recognition ability and prediction ability were 100%.(3) The discrimination of Northeast-China black honey based on the values of Sr and Pb isotope ratios. After the data preprocessing, the CA method was applied to the two types of honey, and they could be generally separated with 11 Northeast-China black honey samples were mis-classed as linden honey samples. By PLS-DA, the recognition ability and prediction ability were 86.5% and 95.0%, respectively. Therefore, the reliability of PLS-DA model based on the Sr and Pb isotope ratios should be taken into account for the further study.(4) The discrimination of Northeast-China black honey based on mineral elements combined with the values of Sr and Pb isotope ratios. The honey samples could be separated clearly according to the types of Northeast-China black honey and linden honey both in PCA and CA. The accuracy of recognition ability and prediction ability were 100% by PLS-DA. It's obvious that the performance of model based on combined variables were more satisfactory than only based on Sr and Pb isotope ratios.In conclusion, the contents of mineral elements and Sr and Pb isotope ratios could be considered as the essential parameters for the discrimination between Northeast-China black honey and linden honey, especially for the mineral elements. On the other hand, the combined variables could be applied to perfect the discrimination model for Northeast-China black honey.