Glow Discharge Mass Spectrometric Determination of 24 Impurity Elements in Pure Tin and Elimination of Memory Effect of Tin

Glow discharge mass spectrometry (GDMS) was applied to the determination of 24 impurity elements in pure tin, with quantification without reference standards. The pure tin sample should be washed with ethanol, water and ethanol again in succession to remove dust particles from its surface, and then be air-dried before used for analysis. The inter-relationship among the 3 key influential factors, i.e., the voltage, current and gas-flow of glow discharge, and their influences to the intensity of total ionization current during the process of glow discharge supttering and ionization were tested and discussed in this work. And the optimized conditions of glow discharge, under which the GDMS instrument behaved its best state, were found as follows:voltage of 590 V, current of 30 mA and gas flow of 450 mL·min^-1. Mass numbers with higher relative abundance and with less interference under different resolution modes (middle or high) were selected for the analysis, to eliminate the influence of MS interferences in the determination of the impurity elements. Values of RSDs (n=5) found for the elements determined were all less than 15%. Detection limits (3s) found for the 24 elements were in the range of 0.003-0.174 μg·g^-1. The analytical results of the elements determined by the present method were found in consistency basically with those found by ICP-AES or ICP-MS. It was shown by the testing result that the memory effect of tin was completely eliminated by renewing 4 of the easy-consumable spares of the instrument, i.e., the anode cap, the current duct, the sampling cone and the lens.