Microdetermination of Piroxicam in Pharmaceutical Formulations by Complexation with Fe(III) and Image Scanning Densitometry

Piroxicam is a nonsteroidal anti-inflammatory drug (NSAID) that is used to relieve pain or inflammation due to osteoarthritis or rheumatoid arthritis. Assay of piroxicam in pharmaceutical formulations can be performed by using a number of analytical techniques. This work estimates the drug in commercial samples using a novel method, Computational Image Scanning Densitometry (CISD). Micro-volumes of the aqueous solution of piroxicam were reacted with iron(III) sulfate solution under optimum conditions on a white Teflon well plate to form a pink-colored mononuclear complex. By using a smartphone, the picture of the colored complex in the well plate was taken and transferred to an attached computer. The overall optical density resulting from red, green, and blue (RGB) components from a specific area of the colored image was measured and digitalized with the help of custom-made software. A standard curve was prepared by plotting optical density against piroxicam concentration. The method was simple, fast, adequately precise, and accurate for the assay of the drug in commercial samples. The validity of the new method was checked by comparing the results with those obtained by a standard spectrophotometric method of Piroxicam estimation.