A Direct Quantitative Raman Method for the Measurement of Dissolved Bisulfate in Acid-Sulfate Fluids.

Raman spectroscopy has been applied to the quantitative analysis of the concentration of bisulfate in acid-sulfate fluids at different temperatures. The quantitative analysis method is based on the peak area ratios of [Formula: see text](ν) and HO (ν), where PA([Formula: see text]/HO) = [[Formula: see text]] × (0.0066 × T + 1.3070) at a temperature range of 0-100 ℃. We found that the molal scattering coefficient of bisulfate increases slightly at the elevated temperature may be due to the changes of fraction of water molecules that are hydrogen-bonded. The method can also be applied to analyze physicochemical parameters of other acid fluids, such as hydrogen phosphate, bicarbonate, etc., and especially to the in situ detection of deep sea acid-sulfate hydrothermal fluids in the future.