Characteristics of flow injection inductively coupled plasma mass spectrometry for boron analysis in steels

A method for the determination of Boron in steels by FI-ICP-MS is described. It is shown that flow injection (FI) can alleviate problems arising from high amounts of dissolved solids in Inductively Coupled Plasma Mass Spectrometry (ICP-MS) due to the capability to operate with microliter amounts of sample with a rapid sample rate. Sample dissolution was carried out in a microwave oven using diluted aqua regia (HCl+HNO3, 3+1) and high pressure digestion vessels, which gave notable advantages over conventional dissolution techniques, such as lower costs, greater volatile retention, reduced contamination and faster dissolution rates. The operating parameters in flow injection ICP-MS, such as carrier flow rate, nebulizer flow rate, and injection volume were established. The detection limit obtained when direct sample nebulization was used, with a 0.05% m/v Fe concentration, was 1.2 μg·g-1 B, compared to a detection limit of 0.2 μg·g-1 when the FI system was used with samples containing a higher concentration of dissolved solids (0.5% m/v Fe). The influence of the internal standard on precision and accuracy was studied and Beryllium was selected as the internal standard. The RSDs obtained for four peak area determinations of 200 μl injection volumes of a solution of 100 ng·ml-1 B in the presence of 0.5% m/v Fe were below 1.5%. The accuracy of the method proposed was verified by analyzing Reference Materials (EURONORM-CRM 097-1; BCS 456, 457 and 460; NBS 361, 363 and 365), using an external calibration system with calibration samples, prepared from a standard Boron solution, in the same acid medium as the test sample solutions.Peer reviewe