石墨化碳黑净化-分光光度法测定明胶空心胶囊中的六价铬

Determination of Cr(VI) in vacant gelatin capsules by graphitized carbon black purification-spectrophotometry

中文关键词:  石墨化碳黑  二苯碳酰二肼  分光光度法  六价铬  明胶空心胶囊

英文关键词:graphitized carbon black  diphenylcarbazide  spectrophotometry  Cr(VI)  vacant gelatin capsules

中文摘要:

      建立石墨化碳黑净化-二苯碳酰二肼衍生-分光光度法测定着色明胶空心胶囊中六价铬的含量。方法 样品经磷酸盐缓冲液I提取, 80 ℃水浴振荡1 h, 碱性条件下用石墨化碳黑脱除色素, 二苯碳酰二肼丙酮溶液酸性条件下衍生显色, 10 mm石英比色皿比色, 采用分光光度法在540 nm波长下检测, 扣除本底后以外标法定量。结果 50 mg石墨化碳黑粉末(graphitized carbon black, GCB)对于明胶空心胶囊的着色剂具有较好的脱除效果, GCB在待净化液pH大于12.5的条件下对Cr(VI)的吸附作用不明显, 回收率可达90%以上。样品中Cr(III)的存在对于本方法测定Cr(VI)无显著影响。根据使用的比色皿光程, 方法检出限为1.6 mg/kg或更低。结论 本方法快速准确, 适用于明胶空心胶囊中六价铬的检测。

英文摘要:

      Objective To establish a method for the determination of hexavalent chromium [Cr(VI)] in colored vacant gelatin capsules by graphitized carbon black (GCB) purification-diphenylcarbazide derivatization- spectrophotometry. Methods Samples were extracted with phosphate buffer I, and processed with water bath oscillation under 80 ℃ for 1 h. Then the color was removed from the extract by graphitized carbon black powder (GCB) under the alkaline condition. Finally Cr(VI) was detected by a spectrophotometer with a 10 mm quartz cuvette and measured at 540 nm after derivation with diphenylcarbazide acetone solution under the acidic condition. Then background was deducted and external standard method was used for quantitative analysis. Results The pigments in vacant gelatin capsules could be well removed by using 50 mg GCB powder. The Cr(VI) ions were not obviously absorbed when the pH value of the solution during the purification process was higher than 12.5, as the recoveries were more than 90%. The Cr(III) ions in the samples had no distinct influence on detection of Cr(VI). The limit of detection was 1.6 mg/kg or even lower according to the optical length of the cuvette used. Conclusion The method is rapid and accurate, which is suitable for detection of Cr(VI) in vacant gelatin capsules.