Automatic determination of quinine by atomic absorption spectrometry

Abstract

A flow injection method for the indirect determination of quinine, based on the precipitation of an ion-association species formed between the quinine and Marmé reagent (CdI 4 2−) is reported. The precipitate is obtained by injecting the Marmé reagent into a carrier stream containing the quinine, and is then retained on a filter, the filtrate then being directly aspirated into an atomic absorption spectrometer to determine the unprecipitated cadmium. The calibration graph was linear over the range 5–110 μg ml −1 quinine, and the relative standard deviation for determination of 40 μg ml −1 quinine was 2.1%. The 3σ detection limit was 2 μg ml −1. No other compounds normally found in soft drinks had any effect on the quinine determination. The accuracy of the method was checked by means of the well established fluorimetric method.