Gaziosmanpasa University, Faculty of Science and Arts, Chemistry Department, 60250 Tokat, Turkey.
J Hazard Mater. 2009 Dec 15;172(1):395-9. doi: 10.1016/j.jhazmat.2009.07.021. Epub 2009 Jul 14.
A method for the separation and speciative determination of Cr(VI) and Cr(III) has been developed. The procedure is based on coprecipitation of Cr(III) on 3-ethyl-4-(p-chlorobenzylidenamino-4,5-dihydro-1H-1,2,4-triazol-5-one (EPHBAT) without carrier element. The Cr(III) can be selectively precipitated on EPHBAT in the pH range of 8.0-9.0, while Cr(VI) cannot be retained. Total chromium was determined after the reduction of Cr(VI) to Cr(III) with 0.5 mL of concentrated H2SO4 and 0.5 mL of ethanol. Cr(VI) concentrations were obtained as the respective differences between total chromium and Cr(III). Experiments were performed to optimize conditions, such as pH, amounts of EPHBAT, sample volume, etc. A preconcentration factor of 50-fold was achieved for Cr(III). The detection limit of the method for Cr(III) was 1.0 microg L(-1). To validate the developed method, the certified reference materials (NIST SRM 1573a and GBW 0703) were analyzed. The method was applied for the speciation of chromium in spiked natural water samples with satisfactory results.
已经开发出一种分离和特异性测定六价铬和三价铬的方法。该方法基于三价铬在没有载体元素的情况下与 3-乙基-4-（对氯苯亚甲基-4,5-二氢-1H-1,2,4-三唑-5-酮（EPHBAT）共沉淀。在 pH 值为 8.0-9.0 的范围内，可以在 EPHBAT 上将三价铬选择性沉淀，而六价铬则不能保留。用 0.5 毫升浓硫酸和 0.5 毫升乙醇将六价铬还原为三价铬后，即可测定总铬。六价铬的浓度为总铬与三价铬的相应差值。进行了实验以优化条件，例如 pH、EPHBAT 的用量、样品体积等。三价铬的预浓缩因子达到 50 倍。该方法测定三价铬的检测限为 1.0 微克/升。为了验证所开发的方法，分析了认证参考物质（NIST SRM 1573a 和 GBW 0703）。该方法已应用于加标天然水样中铬的形态分析，结果令人满意。
