El-Ahraf A, Van Willis W, Vinjamoori D V
J Assoc Off Anal Chem. 1981 Jan;64(1):9-13.
The reduction of mercury in samples of dairy cattle and chicken feed rations and manures prepared by acid digestion for determination by flameless atomic absorption is rapidly, smoothly, and quantitatively effected by sodium hypophosphite. The reducing agent is air-stable, is effective over a wide range of mercury concentrations, and is useful in the presence of many mineral acids commonly used for wet digestion of these matrices. The accuracy and precision obtained in determinations with this reagent are equivalent to those obtained using stannous chloride at the same conditions. Recovery efficiencies for the total analytical procedure were studied using cattle manure and feed rations spiked to 0.6 ppm Hg as phenylmercuric nitrate; the range of recoveries varied from 93 to 102% (97% average). The absolute detection limit of the method is 10 ng Hg, and the precision varies in the range of 2.2-6% for samples containing 3 ppt-10 ppm Hg. The advantages of sodium hypophosphite lie in the elimination of premature reduction of mercury caused by traces of stannous chloride adhering to the walls of the reaction vessel, the elimination of several wash steps in the determination, and the long shelf life of the reagent.
通过酸消解制备用于无火焰原子吸收测定的奶牛和鸡饲料及粪便样品中的汞，次磷酸钠能快速、顺利且定量地实现汞的还原。该还原剂在空气中稳定，在广泛的汞浓度范围内均有效，并且在常用于这些基质湿法消解的多种无机酸存在下也适用。使用该试剂进行测定时所获得的准确度和精密度与在相同条件下使用氯化亚锡所获得的相当。采用添加了0.6 ppm汞（以硝酸苯汞形式）的牛粪和饲料进行了整个分析程序的回收率研究；回收率范围为93%至102%（平均97%）。该方法的绝对检测限为10 ng汞，对于含3 ppt至10 ppm汞的样品，精密度在2.2%至6%范围内变化。次磷酸钠的优点在于消除了因反应容器壁上附着的痕量氯化亚锡导致的汞过早还原，在测定中无需进行多个洗涤步骤，并且该试剂保质期长。
