铁砷共沉淀-氢化物发生-原子荧光光谱法测定铜矿中的砷

Determination of arsenic in copper ore by hydride generation atomic fluorescence spectrometry with ironic and arsenic co-precipitation

采用氢化物发生原子荧光光谱法测定铜矿中的砷。样品经盐酸-硝酸溶解,加入三价铁离子,调节溶液pH值,使三价铁与砷形成共沉淀,过滤分离FeAsO_4与铜离子。含砷的沉淀经过浓盐酸溶解,在盐酸介质中用氢化物发生-原子荧光光谱法测定砷量。砷与铜的分离条件为：用氨水调节样品溶液pH到4.5,三价铁离子加入量为20 mg。方法测定范围为0.001%~1%,检出限为0.3μg/g。经过共沉淀处理后,主量元素铜、铅和锌大部分已与砷分离,不干扰砷的测定。用国家一级标准物质对此方法进行验证,所得砷含量与标准值相符,对铜精矿样品平行测定5份,结果显示精密度RSD〈4%,准确度〈2%,可准确测定样品中的砷元素。

The arsenic in copper ores was determined by the method of hydride generation atomic fluorescence spectrometry. The samples of copper ores were dissolved with hydrochloric acid and nitric acid,and then ferric chloride was added in to regulate the p H of the resolution,thus the arsenic was co-precipitated with the ferric ions for the separation of arsenic out of the copper ores. The arsenic-containing precipitation was fused with hydrochloric acid so the content of arsenic was determined by hydride generation atomic fluorescence spectrometry in hydrochloric acid medium. The separation conditions for arsenic from copper were obtained： the p H of sample solution was adjusted to 4. 5 with ammonia water; the addition amount of ferric ion was 20 mg. The determination range of proposed method was 0. 001% ~ 1% with detection limit of 0. 3 μg / g. The results indicated that the most main element of copper was separated from arsenic after co-precipitation treatment without interference to the determination of arsenic. With parallel determination of five copies of copper concentrate national standard material samples for validation of this method,the RSD is less than 4. 0 %,less than 2. 0 % relative error RE,to meet the arsenic content accords with the standard values,can accurate determination of arsenic in the samples.