Quantitative colorimetric analysis of some inorganic salts using digital photography

Abstract

An analytical imaging approach to the quantitation of dissolved chemical species absorbed in the visible spectral region is reported. The approach uses digital images of a series of standard solutions of the target substance and their processing with appropriate software to assign a numeric value to each standard in terms of color intensity. Such a value is directly proportional to the analyte concentration and allows the construction of a calibration graph. The results thus obtained are compared with those provided by the classical spectrophotometricmethod used to run calibration curves for colored substances. The chemical imaging technique is relative simple and affordable; in fact, it can be implemented with a commercially available digital camera and the highly user-friendly public domain software ImageJ, developed by the National Institutes of Health and freely available for download on the Internet. The proposed approach can in theory be used to adapt any classic colorimetric method. In a world dominated by increasingly sophisticated equipment, this analytical procedure relies on straightforward, "solidary" analytical chemical principles; in fact, it can facilitate quantitative determinations wherever the purchase and maintenance of spectrophotometersis unaffordable. © Taylor & Francis Group, LLC.