MAGNESIUM AS A MODIFIER FOR THE DETERMINATION OF BARIUM IN OFFSHORE OIL-WELL WATERS BY DIRECT-CURRENT PLASMA ATOMIC EMISSION-SPECTROMETRY AND FLAME ATOMIC-ABSORPTION SPECTROMETRY

It is shown that the addition of magnesium (5 mg ml-1) to samples for the determination of barium by d.c. plasma atomic emission spectrometry enhances the sensitivity of the analysis and dramatically reduces interference from calcium and strontium at both atomic and ionic emission wavelengths. In the presence of high concentrations of sodium, magnesium is a slightly less effective plasma modifier, but still allows the determination of barium with a precision that is adequate for most practical purposes. Magnesium (in both the presence and absence of sodium) also reduces the interference of alkaline earth concomitants in the determination of barium by atomic absorption spectrometry using a fuel-rich dinitrogen oxide-acetylene flame.