Determination of oxygen, nitrogen and hydrogen in iron and steel by pulse melting-time-of-flight mass spectrometry

The contents of oxygen, nitrogen and hydrogen in iron and steel were simultaneously determined by pulse melting-time-of-flight mass spectrometry. By comparing the mass spectrogram of blank and sample, C⁺, N⁺ and H₂⁺, were used as the analytical lines of mass spectrum. The oxygen, nitrogen and hydrogen in a series of standard samples were determined. The calibration curve was plotted based on the ionic number of analytical lines and mass of elements. According to the standard deviation of blank, the detection limits of oxygen, nitrogen and hydrogen were 0.000015%, 0.00002% and 0.000003%, respectively. The proposed method was applied to the determination of standard sample, and the results were consistent with the certified values. The relative standard deviations (RSD) were 1.4%-7.4%. In this method, the mass spectrum detector was used in the simultaneous and quantitative analysis of oxygen, nitrogen and hydrogen in steel materials. The allowable error of determination results could meet the requirements of national standard and the analysis of gases in steel materials.