Development of non-enzymatic strip for simple and selective determination of urea in water and biological samples

A simple and selective method for the determination of urea based on the paptode technique is described. The sensor was constructed by immobilizing an ionophore on a TLC strip. The procedure is based on the nucleophilic displacement of urea with tetrachloro- p -benzoquinone (chloranil) as an ionophore, and the formed violet-color product was detected using a flatbed scanner. The color of each spot was analyzed to red ( R ), green ( G ) and blue ( B ) values from 0 to 255 using a program written in visual basic (VB) programming language. The calibration graph obtained with the proposed sensor was linear over the range of 0.05–10.00 mg L −1 with a detection limit of 0.01 mg L −1 for urea. Parameters such as pH and concentration of chloranil were optimized. The proposed sensor was successfully applied for the determination of urea in bovine serum, urine and tap water samples.