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1.确定乳酸为螯合滴定中锡(Ⅳ)的良好隐蔽剂。在125—150毫升溶液中,利用乳酸能隐蔽多至200毫克锡而作铅或锌的滴定(pH 5—5.5)。 2.有大量铅或锌,23毫克以上的铋,10毫克镉,6毫克铜,13毫克钴,5毫克镍件随锡时,先以 EDTA 定量络合所有阳离子后,乳酸能完全将 Sn-EDTA 螫合物的 EDTA 置换出,其他螯合物不分解。这样大为提高滴定的选择性,相对误差在±0.4%之内。以此法应用于锡基或铅基合金中锡的测定,快速而准确。
1. Make sure that lactic acid is a good concealment agent for tin (IV) in chelation titration. Titration of lead or zinc (pH 5-5.5) using lactic acid in coverts up to 200 mg of tin in 125-150 ml solution. 2. With a large amount of lead or zinc, more than 23 mg of bismuth, 10 mg of cadmium, 6 mg of copper, 13 mg of cobalt, 5 mg of nickel with tin, with EDTA quantitative complexation of all cations, the lactic acid can completely Sn- EDTA EDTA complex exchange out, the other chelates do not break down. This greatly enhances the titration selectivity, the relative error within ± 0.4%. This method is applied to tin or lead-based alloy tin determination, fast and accurate.