为探究不同混合酸对电感耦合等离子体原子发射光谱法测定土壤中重金属元素(铜、锌、铅、镍和铬)的影响,对土壤进行多晶衍射分析,采用硝酸-高氯酸、盐酸-硝酸、盐酸-硝酸-氢氟酸-高氯酸、盐酸-硝酸-氢氟酸混合酸对4种不同类型土壤(黑钙土、褐土、棕壤、红壤)进行了分析。结果表明:该4种混合酸对标准样品的测定都具有较高的准确性与精确性;不同的混合酸的对不同类型土壤中重金属元素的测定具有一定的影响,其中对铬的影响最大;完全消解体系(盐酸-硝酸-氢氟酸-高氯酸、盐酸-硝酸-氢氟酸混合酸)的测定结果不同程度地高于不完全消解体系(硝酸-高氯酸、盐酸-硝酸混合酸)的结果。所以对于土壤重金属元素的测定,混合酸需要针对土壤类型,重金属元素种类等因素进行选择。

Four different acid mixtures, i.e., ① HNO3-HClO4, ② HCl-HNO3, ③ HCl-HNO3-HF-HClO4 and ④ HCl-HNO3-HF were tested for digestion of soil sample, and their effects on the ICP-AES determination of contents of heavy metal elements (Cu, Zn, Pb, Zn and Cr) in the sample were studied. It was found that high accuracy and precision of analytical results were obtained by either of the 4 acid mixtures in analyzing standard samples of soil. But in analyzing unknown soil samples, significant effects were observed in using the 4 different acid mixtures for digestion of samples of different types (chernozem, umber, brown soil and red soil), and most obvious effect was found with the determination of chromium. It was shown that among the 4 acid mixtures, the mixtures ③ and ④ were able to digest the samples completely and were proved to give higher or in other words better results as compared with the incomplete digesting acid mixtures, i.e., the mixtures ① and ②. In fact, suitable acid mixture should be chosen according to the types of soil samples and kinds of heavy metal elements.