Abstract
150 samples of Lycium chinense grown in various areas in Qinghai Province were collected and the analytical samples were prepared. About 0.5 g of each of the samples was taken and dissolved in 1 mL of H2O and 4 mL of HNO3 by microwave digestion according to the prescribed programme. The solution obtained was used for determination of 24 trace elements (i.e., K, Na, Ca, Mg, Fe, Zn, Cu, Mn, Co, Ni, Pb, As, Cd, Cr, Se, Mo, Sb, Sr, Sn, Pr, Gd, Dy, Hg and Tb) by ICP-MS. Standard curves were prepared by using standard solutions of the 24 elements. Detection limits (3s) of these elements were found in the range of 0.008-10 μg·L-1. Samples from Dulan area were used as matrixes in tests for precision and recovery. Values of RSDs (n=6) for the 24 elements were found in the range of 0.95% to 6.6%. Four portions of the sample were taken for recovery test. Values of the trace elements determined in one portion of the sample were taken as the base data, while standard solutions of 15 trace elements at 3 concentration levels were added separately to the other 3 portions of the sample, and the results obtained were used for calculation of values of recoveries, which were found in the range from 85.0% to 107%. Statistical study of the analytical data of the 24 trace elements by principal component analysis and clustering analysis was done by using the MPP soft ware which was attauched to the intrument. As shown by the results, significant differences of contents of Na, Mg, Ca, Mn, Fe, Co, Ni, Cu, Zn, Cd, Pb, Mo and Pr in various individual samples were observed; samples of Delingha area and Golmud area showed good differentiation; samples from Dulan, Wulan and Nomuhong were distributed in a wide area, their difference were not significant; and high correlation was found between Dy and Gd among the 24 trace elements of Lycium chinense grown in Qinghai Province.
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