塑料中痕量Cr(VI)的RoHS符合性测定及影响因素分析

六价铬Cr(VI)的不稳定性使其成为RoHS(限定有害物质, Restriction of Hazardous Substances)符合性测试的难点之一. 采用分光光度法对塑料中痕量Cr(VI)进行检测, 着重研究Cr(VI)萃取与显色中的过程参数与干扰因素的影响, 并建立了一套试样制备、萃取、显色等标准程序. 研究表明, 采用混合碱萃取法可对Cr(VI)进行有效提取, 同时消除Cr(III)的干扰, 通过排除共存离子影响, 优化萃取、显色、标定过程中pH值、温度和时间等参数, 可使试样和加标溶液的回复率保持在90%～110%之间, RSD＜1%, 校准在低浓度范围(0～500 μg/L)呈良好线性关系. 提出的方法和检测程序具有较高的精确度和灵敏度, 而且操作简单、快速, 为信息产业应对RoHS符合性测试提供了较好的技术支持.

Determination and Factor Analysis of Trace Hexavalent Chromium in Plastics for RoHS Directive

The unstable nature of hexavalent chromium Cr(VI) makes it one of the difficulties in RoHS (Restriction of Hazardous Substances) compliant test. A study on the spectrophotometric determination of Cr(VI) contained in plastics, especially focused on influence of the processing parameters and interference factors in the extract and colorific process of Cr(VI) was performed. And subsequently a set of standard procedures including sample preparation, extraction, colorific reaction were established. It was found that the mixed alkali method could effectively extract Cr(VI) from complicated plastic matrices and eliminate the interference of Cr(III), simultaneously. By the exclusion of the coexisting ions, and optimizing several parameters such as pH, temperature, time and so on, the satisfactory results were achieved because the recovery rates were in the range of 90%～110% both for samples and standard solutions, RSDs were less than 1%, and the calibration exhibited the linear relation in the low concentration range (0～500 μg/L). All the above proved that the present method provided a high accuracy and sensitivity, as well as a simple and rapid procedure, thus offering a good technical support to comply with RoHS directive for the information industry.