Spectrophotometric Determination of Mexiletine Hydrochloride In Pharmaceutical Preparations, Urine and Serum Using Complexing Reagents.


Abstract In this work mexiletine hydrochloride (MH) [1-(2,6-(dimethylphenoxy)-2-aminopropane hyrochloride] has been determined spectrophotometrically, using methyl orange (MO) and xylenol orange (XO). The method involved the addition of 1.5ml 0.1% (MO) or 1.2ml 0.05% (XO) reagents to a certain amount of MH, standard or samples, containing between (5-20 μgml-1) MH. The mixture is shaken for (30 sec.) and diluted to about 23ml in case of MO and to 8ml in case of XO in volumetric flasks using distilled water. The pH was adjusted by adding 1ml phthalate buffer pH 2.8 to the MO mixture and finally completed to 25ml, or with NaOH and HCl to pH 5.5 in case of XO and completed to 10ml. The colored ion-pair formed between MH and the reagents were transferred into separating funnels and extracted using 5.5ml CH2Cl2 and were shaken for 30 – 60s. After separation, the organic or aqueous layers were used for constructing calibration curves for spectrophotometric measurements of MH at 429nm and 438nm in cases of MO and XO respectively. The blanks were carried out in exactly the same way throughout the whole procedure. Molar absorptivity(ε L.mol-1.cm-1), detection limit, limit of linearity(µg.ml-1) and r2 were: 4.2x103, 0.32, 4 and 0.9961 for (MH-MO) and 2.3x103, 1.35, 5 and 0.9961 for (MH-XO) respectively. The method was used with reasonable accuracy and precision of(1.6-3.6 E%) and (±1-3.6 S.D%) respectively, for the determination of (MH) in synthetic samples of real blood, urine and capsules.