Determination of ascorbic acid in soft drinks and fruit juices part 1. Background correction for direct ultraviolet spectrophotometry

Abstract

For the determination of ascorbic acid in soft drinks and fruit juices, spectrophotometry is the most commonly used instrumental method. Although UV spectrophotometry is a fast and simple method, matrix interference has been shown in this work to be a problem that can be solved by correcting the background absorption. Background correction methods such as thermal decomposition, catalytic conversion, UV light decomposition and alkaline treatment have therefore been investigated and evaluated. The alkaline treatment method was found to be the best for the concentrations normally encountered in commercial drinks. Hence, its working parameters have been optimised and their effects on the analysis are discussed.