Analytical application of inorganic salt standards and mixed-solvent systems to trace-metal determination in petroleum crudes by atomic-absorption spectrophotometry

Abstract

The determination of Ni, Cu, Zn, Na, Pb, Cd and Fe in petroleum crudes by means of a toluene-acetic acid mixed-solvent system, inorganic salt standards and atomic-absorption spectrophotometry is presented. The low systematic errors and good burning characteristics of this mixed-solvent system led to its choice. Good recoveries of metals added to petroleum crudes are demonstrated. Coefficients of variation of 8.4 for Ni, 7.0 for Cu, 7.8 for Zn, 11.2 for Na, 9.8 for Pb, 10.2 for Cd and 13.9% for Fe are obtained. The validity of the method is shown by comparison of results obtained with those of an established method.