Coincidence Profiles for Sulfur Emission at 180.73 nm (Third Order) in ICP-AES

Coincidence profiles of eleven prevalent concomitant elements, on the sulfur emission line at 180.73 nm in the third order, were procured by scanning the sulfur channel of a vacuum argon ICP-AES using the polychromator primary slit. VUV, as well as UV emission lines above 250 nm in the second order were observed, despite the fact that an interference filter with less than 2% transmission above 250 nm was located before the channel photomultiplier. Spectral interferences from Ca (1000 mg/L), Si (1000 mg/L), Cr (200 mg/L), and Ti (200 mg/L) were attributed to VUV emission lines; those from Mn (200 mg/L) to a UV line above 250 nm in the second order; and those from Fe (1000 mg/L) and V (200 mg/L) to VUV as well as UV lines. Background enhancement was exhibited by Al (1000 mg/L), Ni (200 mg/L), and Mg (1000 mg/L). Cu (200 mg/L) did not interfere. A simple procedure for distinguishing VUV from UV lines, by using the argon purge nozzle of the vacuum ICP-AES as an air optical filter, is demonstrated. The procedure is useful for facilities where a scanning monochromator is not available.