Fourier transform infrared determination of CO2 evolved from carbonate in carbonated apatites

A quantitative method based on FTIR has been developed to determine carbona te in synthetic apatites. The method measures the evolved CO2 after reactio n of 50 mg apatite with 2 mL of hydrochloric acid (0.5 M) in a reaction ves sel, heated to 40 degrees C. The CO2 evolved was swept by a carrier of nitr ogen to a laboratory-made infrared gas cell of 39 mm pathlength and 490 mu L volume. The signals were recorded as a function of time and the areas of the chemigram peaks obtained from the measurements in the wavenumber range of 2500-2150 cm(-1), were interpolated using a calibration curve. The metho d can be used to study apatites with carbonate contents below 0.2% with a s ampling frequency of 8 h(-1).