Coincidence Profiles for Phosphorus Emission at 178. 287 nm Observed in the Third Order by Inductively Coupled Plasma Emission Spectrometry

Spectral interference profiles for 11 concomitants on phosphorus emission at 178.287 nm observed in the third order were acquired by scanning the phosphorus channel of a simultaneous vacuum argon inductively coupled plasma emission spectrometer, using the polychromator primary slit. Vacuum ultraviolet (vacuum UV) as well as UV emission lines were observed, despite the fact that an interference filter with less than 2% transmission above 250 nm was located before the channel photomultiplier. Spectral interference from Si (1000 mg/L) was attributed to a vacuum UV emission line at 178.32 nm, from Mn (200 mg/L) and Cr (200 mg/L) to UV lines at 267.42 and 267.36 nm, respectively, observed in the second order. Fe (1000 mg/L), Al (1000 mg/L), and Mg (1000 mg/L) exhibited background enhancement. V (200 mg/L), Tl (200 mg/L), Ni (200 mg/L), Cu (200 mg/L), and Ca (1000 mg/L) did not interfere with titanium and nickel showing vacuum UV emission lines at 178.26 and 178.34 nm, respectively, that may wing-overlap the phosphorus line at higher concentrations. A simple technique for distinguishing vacuum UV from UV lines by using the spectrometer argon purge nozzle of a vacuum inductively coupled plasma atomic emission as an air optical filter was demonstrated. The technique Is useful for facilities where a scanning monochromator Is not available.