摘要：The analysis of siliceous matrix samples may adopt a two-step pretreatment, which includes melting with ammonium hydrogen fluoride and redissolving with nitric acid. However, the residual of substrate silicon unfavorable to the determination of trace elements in the samples due to serious matrix effects.
Here, a new digestion method using simultaneously both ammonium bifluoride and nitric acid under normal pressure was developed for high-purity quartz sand sample. The digestion pretreatment is a two step process: melting/dissolving with both ammonium bifluoride and nitric acid at 200 _x005f_x005f_x005fC for 2 h, and

evaporating the solution at 250 C to dryness. As confirmed by XRD analysis, silicates in the sample were converted to (NH4)3SiF6NO3 in the melting/dissolving step. TGA analysis shows that the generated (NH4)3SiF6NO3 could be decomposed and evaporated completely at 250 C, which ensured a complete removal of silicon by the followed evaporation of the solution at 250 C. As a result, the followed ICP-OES and ICP-MS analysis needed a solution dilution of only 100 times for the determination of Ca, Mg, Al, Rb,Ba, REE and other trace elements. The new method was applied to the analysis of three certified reference materials, and the results were well consistent with the standard value with RSD% values

关键词：Digestion, SiO2 matrix elimination, Ammonium difluoride, Trace elements analysis, Mass spectrometry