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地球化学找矿,要求钨的检出限低至0.5μg·g~(-1),通常的光谱分析方法尚难满足这一要求。为此,许多光谱分析工作者为降低其检出限进行了多方面的研究,如利用氯化反应,钨的直接测定检出限达到1～5μg·g~(-1),采用溶液载体、钨的检出限降至0.7～0.8μg·g~(-1)。这些方法对于钨背景值较高的区域扫面样品分析,基本能满足地质上的要求,但尚难全面适用检出限为0.5μg·g~(-1)的地质工作需要。本法利用较氯化反应更具选择性的硫化反应,以含20%K_2CO_3的沉降硫作反应剂,在电极底部垫缓冲层,采用直流电弧光源、阳极蒸发、两台摄谱仪共光源联合接收紫外和可见两波段光谱,其直接测定检出限CL分别达到W 0.4、Mo 0.21、Sn 0.16、Bi 0.18、Pb 0.94,除Bi外,其余元素的检出限均低于规定值,实现了钨等元素的连续直接光谱测定。各元素的相对标准偏差RSD%在5.5%～12.5%之间。
Geochemical prospecting requires that the detection limit of tungsten be as low as 0.5 μg · g -1, which is not met by the usual methods of spectroscopic analysis. To this end, many spectral analysis workers to reduce the detection limit of a wide range of studies, such as the use of chlorination, direct detection limit of detection of tungsten reached 1 ~ 5μg · g -1, using a solution carrier, The detection limit of tungsten dropped to 0.7 ~ 0.8μg · g ~ (-1). These methods can basically meet the geological requirements for the scanning analysis of the samples with high tungsten background area, but it is difficult to fully apply the geological working requirement with the detection limit of 0.5 μg · g -1. This method uses a more selective than the chlorination reaction vulcanization, with 20% K_2CO_3 precipitated sulfur as a reactant in the pad bottom electrode pad, the use of DC arc light source, anodic evaporation, co-light source with two spectrographs The UV detection and the visible two-band spectroscopy, the direct detection limit CL reached W 0.4, Mo 0.21, Sn 0.16, Bi 0.18, Pb 0.94, except for Bi, the remaining detection limits were lower than the prescribed value, to achieve Tungsten and other elements by continuous direct spectrophotometry. The relative standard deviation RSD% of each element is between 5.5% ~ 12.5%.