本文报导,在海他西林粉剂和制剂中用Ni(Ⅱ)-二甲亚砜试剂测定小量氨苄青霉素的方法,以及影响测定的各种因素。本法基于在无水情况下,于二甲亚砜溶剂中,Ni(Ⅱ)选择性地与氨苄青霉素形成一个无生物活性而于830毫微米处有紫外吸收峰的化合物。而海他西林与镍试剂则无反应。本法的测定误差一般小于±5～10％。实验方法:Ni(Ⅱ)-二甲亚砜试剂:取2.6克 This paper reports a method for the determination of small amounts of ampicillin using the reagent Ni (II) -dimethyl sulfoxide in Hetacillin powders and formulations, as well as the various factors that influence the assay. This method is based on the selective formation of Ni (II) with ampicillin in the absence of water to form a compound with no biological activity at 830 nm with an UV absorption peak. The hetacillin and nickel reagents are non-reactive. The measurement error of this method is generally less than ± 5 ~ 10%. Experimental Methods: Ni (Ⅱ) - dimethyl sulfoxide reagent: Take 2.6 grams