A direct method for the determination of carbonate and non-carbonate carbon in geological materials by infrared spectrometry

A simple and direct infrared method for determining carbonate and non-carbonate carbon in geological samples is described. To determine carbonate carbon, hydrochloric acid is added directly to the heated samples; non-carbonate carbon is determined by combustion after digesting the samples with hydrochloric acid. The limit of detection is 2 ppm for carbonate carbon and 10 ppm for non-carbonate carbon; the relative standard deviations are 4% or less for 100–1000 μg of carbonate and non-carbonate carbon. The method has been applied to standard rocks, NBS minerals and geological exploration reference samples.