Application of Oxidative Coupling Reactions for the Estimation of Monobenzone in Bulk Sample and Dosage Forms.

Abstract

Five simple and sensitive visible spectrophotometric methods
(method A, method B, method C, method D and method E) have
been developed for the estimation of monobenzone (MB) in bulk
and pharmaceutical fonnulations. These methods are based on the
oxidative coupling reactions of monobenzone with 3-methyl-2-
benzothiazolinone hydtazone (MBTH) in presence of sodium metaperiodate
(NaIO₄) (method A,   λ_max 520 nm), 4-aminophenazone
(4-AP) in presence of potassium fenicyanide (K₃[Fe(CN)₆] (method
B,  λ_max 500 nm), N,N-dimethyl amino-p-phenylenediamine'
(DMPD) in presence of sodium metaperiodate (NaIO₄) (method C,
λ_max 640 nm), p-amino-phenol (PAP) in presence of molecular
oxygen (method D,  λ_max 620 nm) and 2,6-dichloroquinone-4-
chlorimide (DCQC) in presence of buffer pH 9.4 (method E,
λ_max 600 nm). Beer's law limits, precision and accuracy of these
methods are checked by the UV reference method. The results
obtained in the five methods are reproducible and are statistically
validated and found to be suitable for the assay of monobenzone in
bulk and pharmaceutical formulations.