A first-derivative spectrophotometric method for the determination of irbesartan (IRB) alone and in the presence of hydrochlorothiazide (HCT) is described. Measurements are made at the zero-crossing wavelength at 263.0 nm for IRB. The calibration graph was linear over the range 1.0-12.0 mg l(-1) of IRB, detection limit was 0.15 mg l(-1). HCT, in the presence of IRB was determined by direct spectrophotometric method at 317 nm. The calibration graph was linear over the range 2.0-50.0 mg l(-1) of HCT, detection limit was 0.25 mg l(-1). The proposed methods were successfully applied to the determinations of IRB and HCT in combined tablets.
[Show abstract][Hide abstract] ABSTRACT: A simple and accurate method is presented for determination of irbesartan in pure form and commercial dosage forms. The method is based on the reaction of the above cited drug with bromophenol blue (BPB), bromocresol purple (BCP), bromothymol blue (BTB) and naphthol blue black (NBB) dyes in solutions containing Britton buffer to form ion-pair complexes extractable with chloroform and subsequently measured spectrophotometrically at 420nm for BPB, BCP, BTB and 625nm for NBB. All the reaction conditions for the proposed method have been studied. The reactions were extremely rapid at room temperature and the absorbance values remains unchanged up to 24hrs. Beer's law was obeyed in the ranges 1.8-45, 1.5-43, 2-60 and 10-244 g/mL for BPB, BCP, BTB and NBB, respectively. Interferences of the other ingredients and excipients were not observed. The proposed method is simple, fast and sensitive, and the first reported extractive method for the determination of irbesartan.
[Show abstract][Hide abstract] ABSTRACT: Derivative spectrophotometry offers a useful approach for the analysis of drugs in multi-component mixtures. In this study a third-derivative spectrophotometry method was used for simultaneous determination of anthocyanoside and beta-carotene using the zero-crossing technique. The measurements were carried out at wavelengths of 625 and 540 nm for anthocyanoside and beta-carotene respectively. The method was found to be linear (r 2 >0.999) in the range of 125-750 µg/mL for anthocyanoside in the presence of 25 µg/mL beta-carotene at 625 nm. The same linear correlation was also obtained (r 2 >0.997) in the range of 6.25-37.50 µg/mL for beta-carotene in the presence of 500 µg/mL of anthocyanoside at 540 nm. The limit of determination was 125 and 6.25 µg/mL for anthocyanoside and beta-carotene respectively. The method was successfully applied for simultaneous determination of anthocyanoside and beta-carotene in pharmaceutical preparations without any interferences from excipients. INTRODUCTION Anthocyanosides of Vaccinium myrtillus L. (a well known medicinal plant) has been marketed in combination with beta-carotene mostly as tablet (1). Oral administration of this preparation is commonly used for treatment of ophthalmic and vascular disorders (2). Literature survey showed that in several pharmacoepias such as BP, USP or EP no official procedure is present for simultaneous determination of anthocyanoside and beta-carotene in pharmaceutical preparations. Analysis of this combined drug usually per-formed through spectrophotometric procedures of each individual compound after separation from the mixture. These procedures are time-consuming and relatively complicated. Derivative spectrophotometry provides a greater selectivity than common spectrophotometry and offers a powerful approach for resolution of band overlapping in quantitative analysis of multi-component mixtures (3, 4). The presence of numerous of maxima and minima is another advantage that provides an opportunity for determination of multi-component mixtures. In the last 20 years, this technique has been rapidly gained its application in the analysis of various pharmaceutical preparations such as simultaneous determination of cephalotin and cefoxitin (5), irbesartane and hydrochlorthiazide (6), dicloxa-cillin and ampicillin (7), metronidazole and ciprofloxacin (8), fosinopril and hydro-chlorthiazide (9), trifluoperazine hydrochloride and isopropamide iodide (10), estradiol and medroxyprogesterone acetate (11), guaiphenesin in anti-tussive preparations (12), amlodipine in the presence of its degradation products (13), stability determination of doxazosin mezylate and celecoxib (14) and also trifluoperazine hydrochloride in the presence of its degradation product (15). The aim of this study was to develop a simple, fast and sensitive derivative spectrophotometric method for simultaneous determination of anthocyanoside and beta-carotene in pharma-ceutical preparations on the basis of zero-crossing measurement. This method could be applied for determination of both drugs in the presence of each other.
[Show abstract][Hide abstract] ABSTRACT: A second-derivative spectrophotometric method for the simultaneous determination of irbesartan (IRB) and hydrochlorothiazide (HCT) in tablets is described. Measurements were made at the zero-crossing wavelengths at 230.1 nm for IRB and 232.7 nm for HCT. The calibration graphs were linear in the range of 14.4–33.6 mg L for IRB and 1.2–2.8 mg L for HCT. The limits of quantitation were 5.0 and 1.1 mg L. The proposed method was successfully applied to the simultaneous determination of IRB and HCT in commercial tablets with a high percentage of recovery, good accuracy, and precision.
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