Digital image-based colourimetric tests for amphetamine and methylamphetamine

Digital image analysis was applied to the products of simple colourimetric tests for amphetamine and methylamphetamine. Adobe Photoshop software was used for colour analysis to obtain analytical data in the form of a Red Green Blue (RGB) value. Calibration curves were developed for each compound and a number of illicit amphetamine samples were analyzed to demonstrate the application of the technique. A wide linear range and low detection limit for both drugs under test facilitated the application to illicit samples. Good agreement with gas chromatographic quantification results was obtained for the illicit samples analyzed by this method. The results show great potential for use as a semi-quantitative field test for illicit drug compounds. Copyright (C) 2011 John Wiley & Sons, Ltd.