On the Detection of Creatinine by Electron Transfer

Maschke devised a test for creatinine employing sodium potassium tartrate cupric complex and sodium carbonate since a white solid is separated.In this communication the chemistry of this test is provided, with the reaction mechanism and electron flow.From the two tautomeric forms of creatinine, the structure with an imino group was selected because a negatively charged nitrogen atom derived from this group is idoneous for an electron transfer to cupric ion.Creatinine is a poly functional molecule, but the lactam can isomerize to the lactim form.The alkaline medium derived from sodium carbonate forms the lactim enolate which can donate electrons to a pair of conjugated imino groups, via a concerted mechanism.This way, the required negative nitrogen atom for electron transfer is formed.One electron is accepted by cupric ion, giving white cuprous sulphate.The remaining electron in the organic molecule is transferred to another cupric ion, leaving a positive charge at nitrogen.Neutralization with water gives the 2-hydroxylamino derivative.