Analysis and suppression of scattering interference for arsenic using dispersive atomic fluorescence spectrometry based on an ultraviolet digital micromirror device spectrometer

Scattering interference (SI) is the possible scattering of intense radiation from the source, which is superimposed directly onto the resonance fluorescence signal of interest. It will lead to sham high results when using a non-dispersive optical system for As detection. To solve the SI of As, in this paper, a real-time suppression method named the non-fluorescent line ratios (NFLR) method was proposed after detailed analysis using dispersive atomic fluorescence spectrometry based on an ultraviolet digital micromirror device spectrometer (UV-DMD-AFS). Specifically, according to the characteristic of fast wavelength selection of UV-DMD-AFS, the source of SI and the effect of external factors on SI were analyzed, the non-fluorescent lines of As and the ratios of non-fluorescent lines to fluorescent lines (simplified as "Ratios") were determined, and the stability of the Ratios was studied under different parameters. The NFLR method suppressed the SI of As effectively, whose suppression proportion was 98.50-102.43%. Compared with the non-dispersive AFS, the NFLR method had a higher long-term accuracy (>99.20%) validated with certified reference materials (CRMs) of water quality samples.