摘要：
足金样品的检测有着广泛市场需求,但常用的火焰原子吸收光谱法(FAAS)、电感耦合等离子体原子发射光谱法(ICP-AES)对于铅、镉质量分数均小于0.0001% 的足金样品无能为力,而电感耦合等离子体质谱法(ICP-M S)标准加入校正-内标法不能用于银、铜含量高(质量分数均大于0.001%)的足金样品检测.采用王水溶解样品后直接用乙酸乙酯萃取,以2% ~5%(体积分数)硝酸为测定介质,建立了ICP-M S测定纯度为99.9% ~99.999% 足金中铜、银、铅、镉4种主要杂质元素的方法.干扰试验表明,足金中高含量银对测定铜、铅、镉没有干扰.在选定的实验条件下,各元素校准曲线的相关系数不小于0.9994,方法测定下限为0.01~0.19 μg/g.将实验方法应用于足金实际样品分析,结果的相对标准偏差(RSD,n=6)为1.3% ~2.6%,加标回收率为99% ~105%.采用实验方法对3种纯度(99.9%、99.99%、99.999%)足金样品中的铜、银、铅和镉进行测定,测得结果分别与原子吸收光谱法(AAS)或ICP-M S标准加入校正-内标法基本一致.方法可实现纯度为99.9% ~99.999% 足金中银、铜、铅、镉的测定.%The detection of pure gold sample has extensive market demand.However,the commonly used flame atomic absorption spectrometry(FAAS)and inductively coupled plasma atomic emission spectrome-try(ICP-AES)were unable to determine pure gold samples when the mass fractions of lead and cadmium were both less than 0.0001%.In addition,inductively coupled plasma mass spectrometry(ICP-MS)with standard addition correction-internal standard method could not be used for determination of pure gold samples with high content of silver and copper(the mass fraction were both higher than 0.001%).After the sample was dissolved with aqua regia,the sample solution was directly extracted with ethyl acetate. Then a determination method of four main impurity elements including copper,silver,lead and cadmium in pure gold with purity in range of 99.9%-99.999% by ICP-MS was established with 2%-5%(volume fraction)nitric acid as determination medium.The interference tests indicated that the high content silver in pure gold did not interfere with the determination of copper,lead and cadmium.Under the selected ex-perimental conditions,the correlation coefficients of calibration curves for all tested elements were not less than 0.9994.The low limit of determination was 0.01-0.19μg/g.The proposed method was applied for the analysis of pure gold actual samples.The relative standard deviations(RSD,n=6)of determination results were between 1.3% and 2.6%.The recoveries were between 99% and 105%.The experimental method was used for the determination of copper,silver,lead and cadmium in pure gold samples with three kinds of purity(99.9%,99.99% and 99.999%).The results were basically consistent with those obtained by atomic absorption spectrometry(AAS)or ICP-MS with standard addition correction-internal standard method.The proposed method was applicable for the determination of copper,silver,lead and cadmium in pure gold with purity in range of 99.9%-99.999%.
