【摘要】 <正> 随着科学技术的发展以及科学实验的需要,对化学试剂纯度的要求越来越高。如在MOS器件中,痕量的钠、钙等杂质离子的存在就严重地影响器件的稳定性、可靠性及成品率,因此,MOS级化学试剂中的杂质的含量必须严格控制在10^-5％以下。钙是常见元素,来源很多,极易对各类试剂造成污更多还原

【Abstract】 A new method of spectrophotometric determination of trace calcium in acids, salts and ammonia, in cit.-EDTA medium of pH 1.5～2.5, has been studied. The colorant, p-ethanoylcarboxyazo, showed high sensitivity and selectivity for calcium. Analytical results for some acids, salts and ammonia are in accord with those by A. A. The coefficient of variation (5～8 determinations) was<6.4%. The percent recovery of standard addition test was 95～105%. Calcium in phosphorous acid can be determined directly.更多还原