锑膜电极检测天然彩棉和染色棉中痕量重金属

Determination of trace heavy metals in naturally colored cotton and dyed cotton by antimony film electrode for electrochemical stripping method

以锑膜电极为工作电极，采用微分脉冲阳极溶出伏安法直接测定天然彩色棉和染色棉样品中痕量铅和镉，考察了支持电解质、锑膜浓度、富集电位和富集时间等因素对检测结果的影响。结果表明，在0．01mol/LLHCl溶液中，锑膜质量浓度350μg／L，富集电位-1．2V，富集时间180s的条件下，锑膜电极对铅和镉的氧化溶出具有良好的电化学响应。当Pb（Ⅱ）和cd（Ⅱ）离子的质量浓度在5-100μg／L的范围内，其阳极溶出峰电流与Pb（Ⅱ）和Cd（Ⅱ）浓度呈良好的线性关系，Ph（Ⅱ）和Cd（Ⅱ）的检出限分别为．52μg/L0．82μg/L。利用锑膜电极连续测定50μg/LPh（Ⅱ）和Cd（Ⅱ）15次，相对标准偏差分别为4．7％和6．3％，说明该方法具有良好的重现性和稳定性。将该方法应用于天然彩色棉和染色棉中痕量Ph（Ⅱ）和Cd（Ⅱ）的测定，其测定结果与电感耦合等离子体质谱法测定结果基本一致。

In this work, an antimony film electrode （SbFE） is used as a possible alternative for electro- chemical stripping analysis of trace Pb（Ⅱ） and Cd（Ⅱ） in naturally colored cotton and dyed cotton samples. The SbFE is prepared in situ on a glassy carbon substrate electrode and employed in combination with anodic stripping voltammetry. Several key operational parameters influencing the electro analytical re- sponse of SbFE are examined and optimized, such as supporting electrolyte, antimony ion concentra- tion, deposition potential and deposition time. Under the condition of HCI solution 0.01 mol/L, concentra- tion of antimony film 350 μg/L, deposition potential - 1.2 V and deposition time 180 s, the antimony film electrode has good electrochemical response to lead and cadmium oxidation. The electrode reveals good linear behavior in the examined concentration ranging from 5 to 100 μg/L for both Pb（Ⅱ） and Cd（Ⅱ）, with a limit of detection （SIN=3） of 0.52 μg/L for Pb（Ⅱ）, 0.82 μg/L for Cd（Ⅱ）. The reproducibility of the analytical signals is characterized by a relative standard deviation （RSD） of 4.7% for Pb（Ⅱ） and 6.3% for Cd（Ⅱ） （50 μg/L, n=15）. The SbFE is successfully applied to determine Pb and Cd in naturally colored cotton and dyed cotton samples, and the results are in agreement with those of inductively coupled plasma-mass spectrometry （ICP-MS）.