灰化法磷测定中不同灰化助剂的效果比较:以焦磷酸钠作为磷标样

A comparison of efficiency of different assistants used in phosphorus determination by ignition method with Na_4p_2O_7 as standard phosphorus

对Na4P2 O7加入不同灰化助剂经不同温度 ( 2 0 0～ 550℃ )灼烧后磷的回收率进行了研究 .所研究的灰化助剂除文献中已深入研究过的MgSO4和Mg(NO3) 2 外 ,还对MgCl2 等 1 0余种盐试剂进行了实验 .结果表明 ,除Mg(NO3) 2 外 ,MgCl2 ,MgAc2 ,CaCl2 ,Ca(NO3) 2 等均能使Na4P2 O7灰化后的磷完全回收 (灼烧温度不低于 450℃ ) ,而加入MgSO4在任何灼烧温度下磷的回收率均低于 80 % ,效果不佳 .因此 ,在利用目前已被广泛应用的由Sol幃ｒｚａｎｏ和Ｓｈａｒｐ所提出的方法去分析篕械目帕A缀妥芰谆蛴谢逯械牧资?,应当用MgCl2 (或MgAc2 )作为灰化助剂来取代MgSO4.

Researches on phosphorus recoveries from sodium pyrophosphate (Na 4P 2O 7) after ignition at temperature from 200 to 550 ℃ with auxiliary, such as MgSO 4, Mg(NO 3) 2, MgCl 2, MgAc 2, CaCl 2, Ca(NO 3) 2 and so on, are finished. The results indicate that MgSO 4 gives poor phosphorus recovery at any ignition temperature from 200 to 550 ℃, when the final residue is extracted with 0.2 mol/dm 3 HCl at 80 ℃ for 30 min. By contrast, Mg(NO 3) 2, MgCl 2, MgAc 2, CaCl 2 and Ca(NO 3) 2 give very good phosphorus recovery with ignition temperature being equal to or greater than 450 ℃.It is suggested that MgCl 2 (or MgAc 2) rather than MgSO 4 can be used as ashing assistant in the phosphorus determination by ignition method.