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有关铬的催化极谱测定,自1963年以来,已有一些报导,但应用于矿物岩石中微量铬的测定,确存在有不少问题。高小霞教授提出的Cr(Ⅵ)—乙二胺(en)—亚硝酸钠体系,灵敏度较高,我们为了解决化探样品中微量铬的测定问题,研究了此体系。在实验中发现,在此体系中加入0.002％的明胶溶液后,波形变好,波高稳定,线性范围变宽。铬的浓度在2.8×10~(-3)—5×10~(-5)μg/ml范围内,峰电流和浓度呈良好的线性关系,可检出0.001 ppb的铬,30多种共存离子对测定无影响。根据实验结果,最好的底液是0.12M NaNO_2,1.8×10~(-3)M en,0.002％明胶溶液。初步应用于化探样品中微量铬的测定,结果令人满意。
There have been some reports about the determination of chromium by catalytic polarography since 1963, but there are many problems in the determination of trace chromium in mineral rock. The system of Cr (Ⅵ) - ethylenediamine (en) - sodium nitrite proposed by Professor Gao Xiaoxia has high sensitivity. To solve the problem of determination of trace chromium in geochemical samples, this system was studied. In the experiment, it was found that after adding 0.002% gelatin solution into this system, the waveform becomes better, the wave height is stable and the linear range is wider. The concentration of chromium was in the range of 2.8 × 10 -3 -5 × 10 -5 μg / ml. The peak current and concentration showed a good linear relationship. Chromium was detected at 0.001 ppb and more than 30 kinds of coexisting ions No effect on the determination. According to the experimental results, the best base solution is 0.12M NaNO_2, 1.8 × 10 -3 M en, 0.002% gelatin solution. The method has been applied to the determination of trace chromium in geochemical samples with satisfactory results.