Analytical evaluation of a water-cooled low gas flow torch for inductively coupled plasma atomic emission spectrometry

Abstract

A water-cooled torch was installed in a Perkin-Elmer Plasma II inductively coupled plasma atomic emission spectrometer for the operation of a low gas flow plasma with total argon consumption of 1.5 l min^–1. Adjustments were required with respect to the coil and the nebulizer. The detection limits are about a factor of three higher than those obtained with the conventional torch in the same instrument. The stability of the system during a 2.5 h period of operation was equal to the conventional plasma. The linearity and linear range of the calibration graphs are also the same for both plasmas. No enhancement of interferences was observed in the low gas flow plasma. A laboratory-built low gas flow plasma instrument was operated at generator frequencies of 27, 40 and 54 MHz. At the higher generator frequencies, the detection limits of the low gas flow plasma are improved by a factor of 2 in the wavelength range from 200 to 250 nm and up to a factor of 4 at higher wavelengths, so that they become equal to the detection limits measured in the conventional plasma.