Method for analyzing acidic substances by high speed liquid chromatography

Abstract

Provided is a process for analyzing acidic substances by high speed liquid chromatography. An aqueous pH indicator solution is incorporated in an effluent from a column packed with a packing material, and the pH indicator-incorporated effluent is monitored by means of spectrophotometry. As the pH indicator, a sulphon phthalein indicator is used, which is at least slightly soluble in water and has a pH transformation range falling within the pH range of from about 3.0 to about 10.0 and which exhibits, when maintained at a pH lower than the pH transformation range, the minimum transmittance at a wave length of about 420-440 nm and, when maintained at a pH higher than the pH transformation range, the minimum transmittance at a wave length of at least about 558 nm. The packing material is preferably a sulfonated styrene/divinylbenzene copolymer having a total exchange capacity of about 4 to 5 milli-equivalent/gram.

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