摘要
采用GB/T 24890—2010中推荐的沸水提取样品前处理方法外,对比了超声提取的样品前处理方法,确定了硝酸汞滴定法测定复混肥料中氯离子含量的最佳试验条件,结果与硝酸银滴定法(摩尔法)的结果基本吻合,相比之下硝酸汞滴定法操作简单,终点稳定且容易判断,回收率为94. 5%～103. 3%,准确度高。此外,还首次采用艾斯卡-半熔法-硝酸汞滴定法测定了复混肥料中总氯,该方法和GB 18877—2009 《有机-无机复混肥料》中爱斯卡混合试剂(Na2CO3和MgO按1∶2研细混匀)-硝酸银滴定法测定氯含量的方法一致,特别适用于沸水提取和超声提取的提取液浑浊或带有深颜色的不易观察滴定终点的复混肥料和有机-无机复混肥料中氯的测定,具有可批量熔样、干扰少、结果准确的特点。
Two pre-treatment methods,boiling-water extraction suggested in GB/T 24890—2010 and ultrasonic extraction,are comparatively used to extract the chloride ions in the samples. The best test conditions of determining the chloridion level in compound fertilizers by mercury nitrate titration are determined,and the results are almost in accord with that of silver nitrate titration. However,the operation of mercury nitrate titration is relatively simple,and the titration end point is stable,easy to judge,the recovery rates of mercury nitrate titration are in the rage of 94. 5% ～ 103. 3% and the accuracy is also higher. Besides,combining with mercury nitrate titration,the escada-semi-melting method is firstly used to determine the total chlorine level in compound fertilizers,which is consistent with the method of determination of chlorine by means of a silver nitrate titration method used mixed flux( Na2 CO3 and MgO blended with 1 ∶ 2) in GB 18877—2009"organic-inorganic compound fertilizer". They are suitable for determining the total chlorine level in compound fertilizers and organic-inorganic compound fertilizer whose extracting solution are turbid or colorful and the end-point is uneasy to judge by boiling-water extraction and ultrasonic extraction. Most of all,the method has the many merits,such as batch melting samples,less interference and high accuracy.
引文
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