Determination of zinc in steel by inductively coupled plasma atomic emission spectrometry with interference correction

The addition of zinc into steel can enhance strength and corrosion resistance. However, excessive zinc addition will compromise material properties. Therefore, accurate determination of zinc content is crucial for producing high-quality steel alloys. In this study, a method for the determination of zinc in steel by inductively coupled plasma atomic emission spectrometry (ICP-AES) was established. Elements causing significant spectral interference with zinc were identified, and their influences were analyzed under varying matrix compositions and sample masses. A mathematical correction model was developed for interference correction of the target spectral lines. The method was validated using various certified reference materials (CRMs) and samples. The results demonstrated that copper caused significant interference with Zn 202.548 nm, while nickel interfered significantly with Zn 213.856 nm. The interference effects of copper and nickel on zinc were stable across different matrices. The interference contribution varied significantly with sample mass, and the determination error correlated with it. After correction, the determination accuracy for six samples was significantly improved using Zn 202.548 nm and Zn 213.856 nm as analytical lines. The Zn 206.200 nm line experienced the minimum interference from coexisting elements and could be selected as the optimal analytical line. The determination range of this method was 0.001 0%-0.10% (mass fraction, the same below), with a linear correlation coefficient of the calibration curve not less than 0.999 8. The limit of detection was 0.000 14%, and the limit of quantification was 0.000 48%. Zinc contents in CRMs/samples were determined using the experimental method, yielding relative standard deviations (RSD, n=11) between 2.2% and 5.7%. The measured results agreed with certified/reference values. Comparison tests showed good agreement between the results of this method and those obtained by inductively coupled plasma mass spectrometry (ICP-MS).