Detecting Contaminants in Water Based on Full Scattering Profiles within the Single Scattering Regime.

Abstract

Clean water is essential for maintaining human health. To ensure clean water, it is important to use sensitive detection methods that can identify contaminants in real time. Most techniques do not rely on optical properties and require calibrating the system for each level of contamination. Therefore, we suggest a new technique to measure water contamination using the full scattering profile, which is the angular intensity distribution. From this, we extracted the iso-pathlength (IPL) point which minimizes the effects of scattering. The IPL point is an angle where the intensity values remain constant for different scattering coefficients while the absorption coefficient is set. The absorption coefficient does not affect the IPL point but only attenuates its intensity. In this paper, we show the appearance of the IPL in single scattering regimes for small concentrations of Intralipid. We extracted a unique point for each sample diameter wherein light intensity remained constant. The results describe a linear dependency between the angular position of the IPL point and the sample diameter. In addition, we show that the IPL point separates the absorption from the scattering, which allows the absorption coefficient to be extracted. Eventually, we present how we used the IPL point to detect the contamination levels of Intralipid and India ink in concentrations of 30-46 and 0-4 ppm, respectively. These findings suggest that the IPL point is an intrinsic parameter of a system that can be used as an absolute calibration point. This method provides a new and efficient way of measuring and differentiating between various types of contaminants in water.