萃取分离-电感耦合等离子体原子发射光谱法测定钢铁中痕量硼

为了降低电感耦合等离子体原子发射光谱法(ICP-AES)测定钢铁中痕量硼的测定下限,满足钢铁中硼质量分数在0.000 1%以下的测定要求,提出了萃取分离与电感耦合等离子体原子发射光谱相结合的方法测定钢铁中痕量硼。采用盐酸-硝酸混酸、硫酸-磷酸混酸和氢氟酸在微波消解仪中溶解试样,然后在pH 0.4～0.8的酸度下,用1,2-二氯乙烷萃取硼与次甲基蓝形成的络合物,萃取完毕后将1,2-二氯乙烷有机相和无水乙醇混合后直接进样,以B 249.678 nm波长作为硼的分析线,在设定的仪器参数下进行测定,方法检出限为0.001 mg/L,换算为钢铁中硼的质量分数为0.000 005%,方法测定下限为0.000 05%。实验方法用于钢铁标准样品和合成样品中痕量硼的测定,测定值分别与认定值或理论值相符,相对标准偏差(n=10)在0.44%～7.3%之间,回收率为92%~100%。

Determination of trace boron in iron and steel by extraction separation-inductively coupled plasma atomic emission spectrometry

In order to reduce the lower limit of quantitation for determination of trace boron in iron and steel by inductively coupled plasma atomic emission spectrometry (ICP-AES) and meet the requirements for determination of boron in iron and steel with mass fraction less than 0.000 1%, a combined method by extraction separation and inductively coupled plasma atomic emission spectrometry was proposed for determination of trace boron in iron and steel. The sample was dissolved with hydrochloric acid-nitric acid mixed acid, sulfuric acid-phosphoric acid mixed acid and hydrofluoric acid in microwave digestion system. Then, the complex formed from boron and methylene blue was extracted with 1,2-dichloroethane at pH 0.4-0.8. The 1,2-dichloroethane organic phase was mixed with anhydrous ethanol for direct injection. The content of boron was determined under the selected instrumental parameters with B 249.678 nm as analytical line. The detection limit of method was 0.001 mg/L, which was 0.000 005% by converting it into the mass fraction of boron in iron and steel. The lower limit of quantitation was 0.000 05%. The proposed method was applied to the determination of trace boron in certified reference materials and synthetic samples of iron and steel. The results were consistent with the certified values or the theoretical values, and the relative standard deviation (RSD, n=10) was between 0.44% and 7.3%. The recoveries were 92%-100%.