高分辨电感耦合等离子体磁质谱法测定含铜不锈钢中痕量磷

作者通过试验,用电感耦合等离子体磁质谱(HR-ICP-MS)测定含铜不锈钢中磷含量时,采用高分辨率模式,选择分辨率为4000,在此条件下磷峰可与干扰双原子分子或离子的峰分开。又通过以含铁基的磷标准溶液优化了气体流量和离子透镜的参数,使磷的信号值提高至3×105cps。而加入45Sc作为内标元素又可显著提高测定的稳定性。分别用不锈钢样品和纯铁粉作基体,加入标准溶液制作标准曲线。结果表明:两种方法的线性均较好,分别测得实际样品的结果及其相对标准偏差也基本一致。但两种方法的检出限(3s)不同,前者为1.0μg·g^-1,后者为0.18μg·g^-1。所提出方法的样品处理过程如下:称取样品0.10g置于消解罐中,加入盐酸溶液2mL及硝酸溶液1mL,待剧烈反应缓解时,将消解罐加盖并置于微波消解仪中,于100℃消解10min,升温至200℃继续消解20min。冷却后将溶液转移至100 mL石英容量瓶中,加入0.2mg·L^-1钪内标溶液1mL,加水至刻度,摇匀。此溶液在仪器工作条件下进行HR-ICP-MS测定。对含磷51μg·g^-1的含铜不锈钢,按本方法测定所得结果的相对标准偏差(n=10)小于4%。应用本方法分析了7种标准物质或已知样品(包括低合金钢、含铜不锈钢、高温合金),并同时用ICP-AES进行校对分析。结果表明,本方法与ICP-AES的测定结果基本一致。但本方法的结果与标准物质的认定值更接近,而且对低含量磷(9μg·g^-1)也可很好测定。

Determination of Trace Phosphorus in Copper-Containing Stainless Steel by High Resolution Inductively Coupled Plasma Magnetic Massspectrometry

Through testing,modifications were made and a method for determination of trace amount of phosphorus in copper containing stainless steel by high resolution inductively coupled plasma magneto-mass spectrometry(HR-ICP-MS)was proposed in this paper.By using resolution of 4000,response peak of phosphorus was well-separated from the interfering peaks of several bi-atomic molecules or ion,thus to have the interferences eliminated.A mixed solution containing 1μg·L^-1 of phosphorus and Fe(Ⅲ)as matrix was used in tuning of the instrument to optimize the parameters of gas flow and ionic lens,the signal of phosphorus was raised to 3×10^5cps.And 45Sc was added as internal standard to overcome the matrix effect and to improve stability of analytical results.Two different ways for preparation of standard curves,i.e.①adding standard solutions of phosphorus to a matrix of stainless steel sample,and②adding standard solutions of phosphorus to pure iron as matrix,were tested comparatively,and as shown by the results,good linearity was obtained for the standard curves prepared by both of the 2ways,and the results of phosphorus together with the values of RSD found by either of the 2curves in analyzing a sample were in satisfactory conformity.However,detection limits(3s)found rom the 2curves were quite different,giving values of 1.0μg·g^-1 for the former way,and of 0.18μg·g^-1 for the latter.Procedure for pretreatment of sample was given as follows:0.10g of the sample was reacted with 2mL of hydrochloric acid and 1mL of nitric acid in the digestion vessel and when the vigorous reaction subsides,the vessel was capped and placed into the microwave digestor,and the digestion of the sample was carried on for 10min at 100℃and for 20min further at 200℃.After cooling,the solution was transferred to a 100mL quartz volumetric flask,and after adding 1mL of 0.2μg·L^-1 scandium internal standard solution,water was added to the mark,and mix thoroughly.This was the sample solution used for HR-ICP-MS analysis under the working condition of the instrument.A Cucontaining stainless steel sample having its P-content of 15μg·g^-1 was analyzed by the propose method,giving value of RSDs(n=10)less than 4%.To test for its accuracy,7CRMs and known samples(including low alloy steel,copper-containing stainless steel,high temperature alloy and etc)were analyzed by the present method and by ICP-AES simultaneously.It was shown that the results of phosphorus found by the 2methods were in consistency,but the results given by HR-ICP-MS method were more closer to the certified values of the CRMs;and that the HRICP-MS method was more effective in determination of phosphorus in trace amount(9μg·g^-1).