Using of 4-Chlororesorcinol as a Coupling Agent in Spectrophotometric Determination of Benzocaine


Simple and accurate spectrophotometric method for the estimation of benzocaine (BENZ) as pure form and in its formulation (ear drops) in aqueous solution has been developed. The method is based on the diazotization of BENZ, with equivalent amount of nitrite, in an acidic medium to yield the diazotized benzocaine. Then the diazotized benzocaine is coupled with 4-chlororesorcinol (4-CRL) reagent in basic medium to formed, an intense yellow azo dye, which is water-soluble and it has good stability. The yellow azo dye exhibits maximum absorption at 436 nm. The relationship between absorbance and concentration gave good range of determination from 10 to 50 μg BENZ in final volume of 10 ml i.e.,1 to 5 μ a molar absorptivity and Sandell's sensitivity index values of 3.722104 l.mol-1. cm-1 and 0.0044 μ respectively, a relative error of –1.06 to +2.47% and a relative standard deviation was not more than 0.921% depending on the concentration level of BENZ, low detection limit of 0.1924 μ and low of quantitation value equal to 0.6416 μ have been estimated. The method has been applied to the estimation of BENZ in ear drop (otocol drops).