A new colorimetric method for determination of procaine in pharmaceutical preparations via oxidative coupling organic reaction


A new and sensitive colorimetric method for determination of procaine in pure and pharmaceutical preparations has been developed. It is based on coupling the nucleus of procaine molecule which is p-amino benzoic acid(PABA) with promathazine HCL in the presence of sodium periodate as oxidizing agent in an acidic medium.The product stable green-bluish coloured has a λ max=610nm.The calibration curve is liner over the range of (0.4-18 µg .ml-1)of p-amino benzoic acid with a molar aborpitivity of 1.718x104 l.mole-1.cm-1,a sandal sensitivity of 0.0079µg.cm-2,a relative error of(-1.15)-2.26% and a relative standard deviation of(0.24-1.45%) depending on the concentration of p-amino benzoic acid.The proposed method is applied satisfactorily to pharmaceutical preparations containing procaine