Quantitation of ranitidine in pharmaceuticals by titrimetry and spectrophotometry using potassium dichromate as the oxidimetric reagent

Abstract

Four new methods are described for the determination of ranitidine hydrochloride (RNH) in bulk drug and in formulations employing titrimetric and spectrophotometric techniques and using potassium dichromate as the oxidimetric reagent. In titrimetry (method A), RNH is treated with a measured excess of dichromate in acid medium, and the unreacted oxidant is back titrated with iron(II) ammonium sulfate. The three spectrophotometric methods are also based on the oxidation of RNH by a known excess of dichromate under acidic conditions followed by the determination of surplus oxidant by three different reaction schemes. In one procedure (method B), the residual dichromate is treated with diphenylcarbazide and the absorbance measured at 540 nm. Calculated amount of iron(II) is added to residual dichromate and the resulting iron(III) is complexed with thiocyanate and measured at 470 nm (method C). Method D involves reduction of unreacted dichromate by a calculated amount of iron(II) and estimation of residual iron(II) as its orthophenanthroline complex after raising the pH, and measuring the absorbance at 510 nm. In all the methods, the amount of dichromate reacted corresponds to the drug content. The experimental conditions are optimized. The titrimetric procedure is applicable over 5-10 mg range. In spectrophotometric methods, Beer's law is obeyed in the ranges 5-50, 5-80, and 10-100 μg ml -1 for method B, method C, and method D, respectively. The methods were validated for accuracy, precision and recovery. The proposed methods were applied to the analysis of RNH in the tablet and the injection forms, and the results were in agreement with those obtained by the reference method.

Instrumental analysis of some anti-ulcer drugs in different matrices

“…[10] Potassium dichromate was used as oxidimetric reagent in spectrophotometric determination of ranitidine in pharmaceuticals. [11] N-bromosuccinimide (NBS) was used as an analytical reagent for the determination of ranitidine HCl. The method involved the reaction of ranitidine HCl with NBS and then the excess NBS was estimated by its reaction with p-aminophenol to give a violet colored product that was measured at λ max 552 nm.…”

Spectrophotometric determination of ranitidine hydrochloride (RNH) in pharmaceutical formulation using 9-fluorenylmethyl chloroformate (FMOC-Cl)

“…The results are given in Table 5. The results obtained by the proposed method were compared with other reported methods [28][29][30][31] . As shown in Table 6, some of the reported methods have higher detection limits 28,31 .…”

“…The results obtained by the proposed method were compared with other reported methods [28][29][30][31] . As shown in Table 6, some of the reported methods have higher detection limits 28,31 . Moreover, some of methods are alike or more sensitive, but have drawbacks such as having a narrow linear dynamic range 29 , involving extraction 8 or being performed at high temperatures 29,-30 .…”

Indirect Determination of Ranitidine Hydrochloride Using a Chloride Ion Selective Electrode

“…Other methods reported for the determination of ranitidine include capillary electrophoresis using UV (Perez-Ruiz et al 2002) or electrochemiluminescent detection (Gao et al 2006), molecular absorption spectrometry (De Almeida and Saferin Martins 1993;Basavaiah et al 2005;Basavaiah and Somashekar 2007). The electrochemical analytical methods applied for R Á HCl determination are: cyclic voltammety (Norouzi et al 2007), polarography (Delgado Zamarreno et al 1985), conductometry (Issa, Youssed, and Mutair 2005), potentiometry, using ion-selective electrodes based on incorporation of ion-pair compounds of R Á HCl, as electro-active substances, in the polymer membrane (Apostu, Bibire, and Tantaru 2008;Issa, Badawy, and Mutair 2005).…”