Paper-based headspace extraction combined with digital image analysis for trace determination of cyanide in water samples

Abstract

A simple, cost-effective, instrumental free and user-friendly analytical method based on the combination of paper-based headspace extraction and digital scanning image analysis was developed for the sensitive detection of cyanide in water and wastewater samples. The method relied on chloramine-T/pyridine-barbituric acid reaction, which is a well-known process for measuring cyanide in standard analytical methods. During the reaction, cyanide was converted to cyanogen chloride, which was extracted and collected on a paper impregnated with pyridine-barbituric acid. The color appeared on the paper was used to quantify the analyte using a scanning-assisted image processing software. Experimental parameters affecting the sensitivity of the method such as stirring rate, paper size, chloramine-T and barbituric acid concentration, equilibrium and extraction time were studied. Under optimal conditions, the calibration curve was linear in the range of 3.0–100 μg L−1 with the detection limit of 0.7 μg L−1. The intra- and inter- day relative standard deviations of the method at 10 and 70 μg L−1 concentration levels were less than 6%. Analyte recovery in real samples was in the range of 69–111%.