Detection of Poisons, Pollutants, Narcotics, and Drugs in Water Using Excitation–Emission Spectroscopy Without Added Reagents

Abstract

This article presents an optical photoluminescence spectroscopic method for the qualitative and quantitative detection of impurities, hazardous materials, pesticides, and pollutants in water. In addition, it lays the groundwork for the development of a potential application to detect, without added reagents, drugs in body fluids. Based on synchronous fluorescence spectroscopy of organic aromatic compounds—specifically, polycyclic aromatic hydrocarbons—the method entails simultaneously monitoring the excitation and emission spectra of the compounds. The full excitation and emission matrix thus generated provides 2D and 3D fluorescence maps of the tested sample. Diagonals through the map origin of the axes provide the synchronous fluorescence spectra at constant, measurable differences between the emission and excitation wavelengths, thus enabling the identification of multiple components. The map, a unique “fingerprint” of the sample, contains all its relevant spectroscopic information and enables very specific and accurate identification of the compounds and their components. Matching between database spectra, the calibration curves of standards and the spectra and the calibration curves from the samples enable accurate identification and quantification of the targeted analyte. The advantages of this method include its sensitivity (detection limits at ppm levels), accuracy, and simplicity of operation. In addition, the spectrometer (the Fluo-Imager prototype) is simple to operate and its maintenance costs are low. The design and performance of the spectrometer, the development of its corresponding software, the analysis of poisons (organic compounds) and their mixtures in water, and our preliminary studies of drugs in body fluids are discussed in this paper.