Determination of arsenic in magnesium and magnesium alloy by hydride generation atomic fluorescence spectrometry
With the increasing application of magnesium and magnesium alloy,there are more and more re-quirements for the determination of harmful element arsenic.The sample was dissolved in nitric acid in batches by heating at low temperature.Then the acidity was adjusted with hydrochloric acid followed by adding 10 mL of thiourea-ascorbic acid solution in order to reduce As(Ⅴ)to As(Ⅲ).Thus,a method for determination of trace arsenic in magnesium and magnesium alloy was established by hydride generation a-tomic fluorescence spectrometry(HG-AFS).Since there are many product types and groups of magnesium and magnesium alloy,such as magnesium-aluminum series,magnesium-zinc series,magnesium-manganese series,magnesium-lithium series and magnesium-rare earth series,the effects of magnesium matrix as well as the maximum content of aluminum,zinc,manganese,copper,nickel,lithium,lanthanum,cerium,praseodymium,neodymium,gadolinium,yttrium,erbium and dysprosium in magnesium alloy on the de-termination of arsenic were investigated.The results showed that the interference of magnesium matrix and major alloying elements in magnesium alloy with the determination of arsenic could be ignored.It was found that the mass concentration of arsenic in range of 1.00-10.00 μg/L had linear relationship with its corresponding fluorescence intensity.The correlation coefficient of calibration curve was 0.999 7.The lim-it of detection of method was 0.001 4 μg/g,and the limit of quantification was 0.004 2 μg/g.Three mag-nesium alloy samples were determined according to the proposed method,and arsenic standard solution was added for recovery test.The relative standard deviations(RSD,n=6)of determination results were between 2.4％and 5.3％,and the recoveries were between 98％and 106％.The method comparison tests indicated that the determination results of the proposed method were basically consistent with those ob-tained by inductively coupled plasma mass spectrometry(ICP-MS).
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