A Microfluidic Device for Presumptive Testing of Controlled Substances*

Abstract

A simple microfluidic device (MFD) has been developed to perform multiple color and crystal tests for controlled substance analysis. The MFD method uses less sample and reagents and generates less waste than traditional spot plate methods while performing several tests simultaneously. This methodology provides significantly more analytical information for a single sample analysis. The current generation device is the size of a microscope slide with four analytical channels: one for microcrystal tests and three for color tests. The optimized devices were subjected to a rigorous validation study using comparative replicate analyses and several operators. Target analytes were methamphetamine, amphetamine, cocaine, and oxycodone and color test reagents used were the Marquis, Simon, and cobalt thiocyanate. For the crystal tests, platinic chloride was used. The validation study showed the MFD's limits of detection to be in the picogram range. Positive tests results were observed in complex mixtures in which the controlled substance was present at concentrations of 5-10% (w/w). The microcrystal reagents showed greater sensitivity than color test reagents when used in the device. Reagent use and waste generation using the devices was 95% less that that used and generated using the traditional methods. The device performance was also shown to be operator independent.