The Determination of Trace Elements in Brine by Atomic Absorption

Abstract

A method for the determination of Mn, Fe, Co, Ni, Cu, Zn, and Pb in oil field brines is described. The elements are concentrated by passing 200 ml of the brine through a column of Dowex A-1 chelating resin. The pH of the resin is adjusted to 4.5 with ammonium chloride. At this pH, the trace metals are retained on the resin and the sodium and other alkali metals allowed to pass through. The metals are then eluted with 1N HCl to a final volume of 50 ml and the concentration of the elements determined by atomic absorption. The method is compared with the standard additions method and coefficients of variation calculated for both methods. The advantages and disadvantages of both methods are discussed. A similar method is described for the extraction and analysis of Ca, Mg, and Sr. Six oil field brines were analyzed using the described method and the results tabulated.