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本文提出了不用邻苯二甲酸二丁酯(DBP)等有机试剂的敌百虫化学分析法,既节约了试剂,又简化了操作,而且分析结果与用DBP的敌百虫分析法相当。我们认为敌百虫经过处理后生成的敌敌畏(DDVP),起着与DBP等有机试剂相似的作用。敌百虫的化学分析法,一般用伏尔哈德返滴定法.即把一定量敌百虫,用Na_2CO_3处理成释放Cl~-的溶液,加入已知过量的AgNO_3标准溶液,以铁铵矾NH_4Fe(SO_4)_2作指示剂,用KSCN标准溶液返滴定剩余量的AgNO_3。其反应如下: (CH_3O)_2PO—C(OH)H—CCl_3+Na_2CO_3→ (CH_3O)_2PO—O—CH=CCl_2+NaHCO_3+NaCl NaCl+AgNO_3→AgCl↓+NaNO_3 AgNO_3(剩余)+KSCN→AgSCN↓+KNO_3 终点 Fe~(3+)+SCN(?)FeSCN~(2+)
In this paper, a chemical analysis method of trichlorfon without using organic reagents such as dibutyl phthalate (DBP) is proposed, which not only saves the reagents but also simplifies the operation, and the analysis results are comparable to the trichlorfon analysis method using DBP. We believe DDVP produced after treatment of trichlorfon plays a similar role as organic reagents such as DBP. The chemical analysis of trichlorfon is generally carried out using the Voltard back titration method, ie, treating a certain amount of trichlorfon with Na_2CO_3 to release the Cl_- solution, adding the known excess AgNO_3 standard solution, NH_4Fe (SO_4) _2 as an indicator, with KSCN standard solution back titration the remaining amount of AgNO_3. The reaction is as follows: (CH 3 O) 2PO-C (OH) H-CCl 3 + Na 2 CO 3 → CH 3 O 2 PO-O-CH = CCl 2 + NaHCO 3 + NaCl NaCl + AgNO 3 → AgCl + NaNO 3 AgNO 3 (remaining) + KSCN → AgSCN ↓ + KNO_3 end point Fe ~ (3 +) + SCN (?) FeSCN ~ (2+)