材料期刊网

以2,6-吡啶二羧酸和1,5-二苯碳酰二肼为衍生试剂,采用柱前和柱后衍生的方式建立了离子色谱法同时测定环境水样中三价铬和六价铬的方法.通过六通阀控制1,5-二苯碳酰二肼注入系统的时间,避免了六价铬衍生液本底对三价铬测定的干扰,提高了三价铬检测的灵敏度,将三价铬的检出限由原来的0.17 mg·L-1降低至5. 9 μg·L-1 .同时,对检测波长、淋洗液浓度、衍生液流速和定量环体积进行了选择优化.该方法对0.72 mg·L-1 Cr(Ⅲ)和0.24 mg·L-1Cr(Ⅵ)峰面积测定值的相对标准偏差分别为0.34%和0.65%,六价铬的检出限为3.2 μg·L-1 .测定了含铬污染废水、电镀厂处理前后的废水和河水共9个样品中Cr(Ⅲ)和Cr(Ⅵ)的含量,并进行了加标回收实验.结果表明,在0.02—0.48 mg·L-1加标范围内,Cr(Ⅲ)的加标回收率在83.7%—117.0%;在0.02—0.24 mg·L-1加标范围内,Cr(Ⅵ)的加标回收率在96.0%—104.5%.

A new method for the simultaneous determination of trivalent and hexavalent chromium in environmental waters was developed by ion chromatography with derivatization reagent injection-control technique using 2,6-pyridine dicarboxylic acid and 1,5-diphenyl carbonhydrazide after pre-and post-column derivatization. The injection time of 1,5-diphenyl carbonhydrazide was controlled by six port valve after finishing the trivalent chromium determination, which avoided the interference of 2,6-pyridine dicarboxylic acid on the trivalent chromium determination and lowered the detection limit of trivalent chromium from 0.17 mg·L-1 to 4.9 μg·L-1. The parameters such as the detection wavelength, eluent concentration, flow rate of derivation agent and volume of quantitative ring were optimized. The peak area repeatability of 0.72 mg·L-1Cr(Ⅲ) and 0.24 mg·L-1Cr(Ⅵ) was 0.34%and 0.65%, respectively, and the detection limit of hexavalent chromium was 3.2 μg·L-1. Cr(Ⅲ) and Cr(Ⅵ) contents in nine environmental water samples such as polluted wastewater,electroplating wastewater before and after treatment, and river waters were determined by the established method. The spiked recoveries of Cr(Ⅲ) were between 83. 7% to 117. 0% with spiked levels of 0.02—0.48 mg·L-1, and the recoveries of Cr(Ⅵ) were between 96.0% to 104.5% with spiked levels of 0.02—0.24 mg·L-1 , respectively.