Computer vision-based analytical chemistry applied to determining iron in commercial pharmaceutical formulations

Two different computer vision-based analytical chemistry (CVAC) methods were developed to quantify iron in the commercial pharmaceutical formulations Ferbisol^® and Ferro sanol^®. The methods involve using a digital camera or a desktop scanner to capture a digital image of a series of Fe²⁺ standard solutions and the unknown sample upon reaction with o-phenanthroline. The images are processed with appropriate software (e.g., the public domain programme ImageJ, from NIH) to obtain a numerical value (analytical signal) based on colour intensity. The fact that such a value is proportional to the analyte concentration allows one to construct a calibration graph from the standards and interpolate the value for the sample in order to determine its concentration. The results thus obtained were compared with those provided by a spectrophotometric method and the US Pharmacopoeia's recommended method. The differences never exceeded 2%. The two proposed methods are simple and inexpensive; also, they provide an effective instrumental alternative to spectrophotometric methods which can be especially beneficial in those cases where purchasing and maintaining a spectrophotometer is unaffordable.