Infrared spectrophotometric determination of the alkalinity of overbased petroleum sulphonates
Abstract
A simple, rapid and selective infrared spectrophotometric method was used to determine the alkalinity of the overbased calcium sulphonate additives. The intensities of the absorbance of the bands at 865 and 1180 cm–1, assigned to the δCO32– and νas SO vibrations, respectively, in the same spectrum of the overbased sulphonate sample were measured. The absorbance ratio method was applied as the path length was not known.