2011 Volume 28 Issue 1 Pages 17-
A flow injection method for cyanide determination was studied using a compact manifold, which is an all-in-one pump, injector, thermostat and detector. It is based on König reaction of ClCN with 4-pyridinecarboxylic acid and 1,3-dimethylbarbituric acid to give blue compound. The absorbance was measured at 605 nm. The chemical factors and FIA variables influencing color development were examined. The constant and maximum absorbance was obtained at a flow rate of 0.76 mL min-1 and a reaction temperature of 50°C, when 0.3 M phosphate buffer solution of pH 6 containing chloramine T (0.1 g L-1) and 4-pyridinecarboxylic acid (0.1 M) – 1,3-dimethylbarbituric acid (0.05 M) mixed solution were used as reagent solutions. Under optimum conditions, with 100 μL sample injection the calibration graph was linear from 0 to 500 ng mL-1 of cyanide. The relative standard deviation was 2 % (n = 10) at the 100 ng mL-1 level. The detection limit and determination limit were 1.5 ng mL-1 (3σ) and 5 ng mL-1 (10σ), respectively. The sampling rate was 20 h-1. The proposed method enable to determine cyanide at even lower levels (< 50 ng mL-1) in a shorter measurement time. This method could be applied to aqueous samples such as the extracts from soil.