Analysis of cobalt, tantalum, titanium, vanadium and chromium in tungsten carbide by inductively coupled plasma-optical emission spectrometry

Abstract

Inductively coupled plasma optical emission spectroscopy (ICP-OES) was used to measure the concentrations of cobalt, tantalum, titanium, vanadium and chromium in solutions of tungsten carbide. The main advantage of the method described here lies in the speed, convenience and effectiveness of the dissolution procedure. Aliquots of powdered tungsten carbide were dissolved in a solution of 5% aqua regia in 30% hydrogen peroxide. Complete dissolution was usually achieved within 10 min. The accuracy of the method was assessed by the analysis of certified reference materials, secondary reference materials and matrix spiking. The method was successfully applied to commercial type samples with differing compositions. Slightly more emphasis was placed on the measurement of vanadium, since no information on the measurement of-this element in solutions of tungsten carbide, by ICP-OES, has been published. The purpose of the study was to provide an alternative, more rapid and less expensive method of dissolving tungsten carbide–cobalt using only nitric acid, hydrochloric acid, hydrogen peroxide and tartaric acid. In this manner, no additional metallic elements were introduced into the sample matrix and the use of hydrofluoric acid was avoided. Investigation of the interference effects of the elements in the sample matrix on each other was essential for accurate results comparable to other published analytical methods.