The determination of oxygen-18 to oxygen-16 ratios in inorganic phosphates by gas-liquid chromatographic-mass spectrometric examination of the tri-n-butyl derivative

Abstract

Aqueous solutions containing inorganic orthophosphates from biological materials were purified on ion-exchange columns and the phosphate was precipitated as its silver salt. The dried silver phosphate was made to react with 1-bromobutane in dimethylformamide, yielding tri-n-butyl phosphate. This solution was suitable for injection directly into a combined gas chromatograph-mass spectrometer for analysis, enabling the oxygen-18 to oxygen-16 ratio of the original inorganic orthophosphate to be determined.