Pressurized Acid Vapor Decomposition of Highly Pure Silica and Determination of Impurities by One-drop Atomic Spectrometry

在带不锈钢护套的双层密封聚四氟乙烯容器中，在高温下同时进行酸的净化和用这些净化的酸蒸气测定高纯二氧化硅。即使从每种金属中含有1毫克的人工污染酸中也能显著降低金属空白水平。采用“一滴”火焰原子吸收光谱仪和电感耦合等离子体原子发射光谱仪对天然白炭黑、约翰逊公司的“镜纯”白炭黑、高纯白炭黑和合成白炭黑中的痕量金属杂质(钠、钙、镁、铜、铁、镁、钛)进行了测定，测定前不需任何其他浓度步骤。以有机溶剂(CCl_4、CHCl_3、CH_2Cl_2和MIBK)为萃合物的金属以一滴火焰原子吸收光谱法测定，进样量为30~40 ul，不需要进行背景校正。将超过50微升的有机萃取物直接注入到空气乙炔火焰中，产生一个有趣的信号轮廓，这取决于感兴趣的金属的种类(铜(I，II)、镉、钴、铁(II，III)、镍和锌)。另一方面，无论金属是否带有一氧化二氮-乙炔火焰，都只能获得正常的信号轮廓。金属的这一有趣的信号轮廓似乎与相应金属氧化物的离解能有关。方法用于国家环境研究所(NIES-CRM，第9号，马尾藻)标准物质中铜的测定，结果与标准值吻合良好。

In a sealed double Teflon vessel with stainelss steel jacket, the purification of acids and the determination of highly pure silica with these purified acid vapors were simultaneously carried out at an elevated temperature. A significant decrease in the metal blank level even from the artificially contaminated acids containing 1 mg of each metal was obtained. Trace metal impurities (Na, Ca, Mg, Cu, Fe, Mm and Ti) in natural silica, "Specpure" silica from Johnson Matthey and highly pure and synthetic silica were well determined by "One-drop" flame atomic absorption and inductively coupled plasma atomic emission spectrometries, without any other concentration step before determination.Metals extracted as their complexes into organic solvents (CC1_4, CHC1_3, CH_2C1_2 and MIBK) were determined by "One-drop" flame atomic absorption spectrometry with injection volume of 30-40 ul and without deuterium background correction. Direct injection of organic extracts of more than 50 ul into an airacetylen flame gives an interesting signal profile, which depends on the kind of metals of interest (Cu(I,II), Cd, Co, Fe(II,III), Ni and Zn). On the other hand, only normal signal profiles are obtained irrespective of metals with a nitrous oxide-acetylene flame. This interesting signal profile of a metal seems to be related to the dissociation energy of the corresponding metal oxide. The method was successfully applied to the determination of copper in certified reference material from the National Institute for Environmental Studies (NIES-CRM, No. 9, Sargasso) and the results agreed well with the certified value.