Determination of cinnamic acid in human urine by differential-pulse polarography

Abstract

The differential-pulse polarographic behaviour of cinnamic acid was studied in acetate and phosphate buffer solutions (pH 3.5–7.5). The reduction mechanism is discussed. The drug can be determined at pH 5.0 over the concentration range 5 × 10^–5–1 × 10^–3 mol l^–1. The effect of tetraalkylammonium salts on the electroanalytical determination of cinnamic acid was investigated. The direct determination of the drug (0.7–5.5 µg ml^–1) in urine samples diluted with acetate buffer (pH 5.0) can be effected in the presence of 1 × 10^–3 mol l^–1 cetyldimethylethylammonium bromide solution. The detection limit was found to be 0.1 µg ml^–1. The relative standard deviation from six determinations at the 5.5 µg ml^–1 level was 1%.