Improving pharmaceutical analysis by incorporating green chemistry and smartphone technology: The assay for dissolution test of ethambutol tablets as an example

Abstract

This work showcases the improvement of the United States Pharmacopeial (USP) assay of ethambutol (ETB) for tablet dissolution test through the incorporation of green chemistry and smartphone technology. In the assay, downscaled extraction was performed in microcentrifuge tubes, utilizing 0.5 mL of chloroform per sample. Instead of spectrophotometric measurements, the extracts were photographed while contained in the closed tubes using a smartphone camera, with white LED serving as the light source. The Red-Green-Blue (RGB) intensities were read out from the image using an RGB Color Detector application. It was found that B/(R + G + B) showed a good linear relationship to the drug concentration over the range of 11.9–118.5 μg/mL (R2 = 0.9992). The method was accurate (% recovery of 99.98–100.91%), precise (% relative standard deviation of 0.97–1.17%), sensitive (LOD = 3.9 μg/mL and LOQ = 11.8 μg/mL), specific and robust. Furthermore, the analysis results obtained were consistent with those obtained through the USP method. The method became greener and safer due to a 20-fold reduction in chloroform consumption and the use of a closed system for signal measurement which prevented the release of solvent vapor into the environment and minimized the analyst's exposure to chemicals. In addition, the method was green with the AGREE score of 0.74, and 9 green shaded sections in the GAPI assessment. Moreover, the data analysis tool in the mobile application developed in this work facilitated rapid and instantaneous calculations of the results. Hence, the assay is feasible for quality control analysis, and helps promote sustainability.