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拟定了在小体积容量瓶中,在KBr存在下,以Fe(Ⅱ)作还原剂,用甲苯作萃取剂,从7.5mol/LH_2SO_4介质中一次性还原萃取砷,再用0.2mol/L KI(pH=9碳酸盐缓冲液)先质溶液一次性反萃取,然后用电生Ⅰ_2作库仑滴定剂,电位法检测终点测定砷的方法。检测限为0.5μg/25mL,测定1～20μgAs(Ⅲ),回收率为100±10％,应用于矿石分析,结果与经典比色法相符。本法还可应用于钢铁分析。
In a small volumetric flask, arsenic was extracted from a 7.5mol / LH_2SO_4 medium with Fe (Ⅱ) as reductant and toluene as extractant in the presence of KBr, and then arsenic was removed by 0.2mol / L KI ( pH = 9 carbonate buffer) precursor solution one-time back-extraction, and then with electricity I_2 for coulometric titration agent, potentiometry method for the determination of arsenic endpoint. The detection limit was 0.5μg / 25mL, the determination of 1 ~ 20μgAs (Ⅲ), the recovery rate of 100 ± 10%, used in ore analysis, the results consistent with the classical colorimetric method. This law can also be applied to steel analysis.