title: Validated spectrophotometric methods for determination of sodium valproate based on charge transfer complexation reactions.
abstract: This work presents the development, validation and application of four simple and direct spectrophotometric methods for determination of sodium valproate (VP) through charge transfer complexation reactions. The first method is based on the reaction of the drug with p-chloranilic acid (p-CA) in acetone to give a purple colored product with maximum absorbance at 524nm. The second method depends on the reaction of VP with dichlone (DC) in dimethylformamide forming a reddish orange product measured at 490nm. The third method is based upon the interaction of VP and picric acid (PA) in chloroform resulting in the formation of a yellow complex measured at 415nm. The fourth method involves the formation of a yellow complex peaking at 361nm upon the reaction of the drug with iodine in chloroform. Experimental conditions affecting the color development were studied and optimized. Stoichiometry of the reactions was determined. The proposed spectrophotometric procedures were effectively validated with respect to linearity, ranges, precision, accuracy, specificity, robustness, detection and quantification limits. Calibration curves of the formed color products with p-CA, DC, PA and iodine showed good linear relationships over the concentration ranges 24-144, 40-200, 2-20 and 1-8μg/mL respectively. The proposed methods were successfully applied to the assay of sodium valproate in tablets and oral solution dosage forms with good accuracy and precision. Assay results were statistically compared to a reference pharmacopoeial HPLC method where no significant differences were observed between the proposed methods and reference method.
authors.affiliation: Pharmaceutical Analytical Chemistry Department, Faculty of Pharmacy, University of Alexandria, Elmessalah, Alexandria 21521, Egypt. Electronic address: tbelaleg@yahoo.com.
authors.forename: Tarek S
authors.initials: TS
authors.lastname: Belal
authors.affiliation: Pharmaceutical Chemistry Department, Faculty of Pharmacy, University of Alexandria, Elmessalah, Alexandria 21521, Egypt.
authors.forename: Dina S
authors.initials: DS
authors.lastname: El-Kafrawy
authors.affiliation: Pharmaceutical Chemistry Department, Faculty of Pharmacy, University of Alexandria, Elmessalah, Alexandria 21521, Egypt.
authors.forename: Mohamed S
authors.initials: MS
authors.lastname: Mahrous
authors.affiliation: Pharmaceutical Chemistry Department, Faculty of Pharmacy, University of Alexandria, Elmessalah, Alexandria 21521, Egypt.
authors.forename: Magdi M
authors.initials: MM
authors.lastname: Abdel-Khalek
authors.affiliation: Pharmaceutical Chemistry Department, Faculty of Pharmacy, University of Alexandria, Elmessalah, Alexandria 21521, Egypt.
authors.forename: Amira H
authors.initials: AH
authors.lastname: Abo-Gharam
mesh_terms: D000927:Anticonvulsants / Q000032:analysis*; D016227:Benzoquinones / Q000737:chemistry; D004304:Dosage Forms; D007202:Indicators and Reagents; D009285:Naphthoquinones / Q000737:chemistry; D013053:Spectrophotometry / Q000379:methods*; D014635:Valproic Acid / Q000032:analysis*
chemical_list: D000927:Anticonvulsants; D016227:Benzoquinones; D004304:Dosage Forms; D007202:Indicators and Reagents; D009285:Naphthoquinones; D014635:Valproic Acid; C007332:dichlone; C014400:chloranilic acid
keywords: Charge transfer complex; Iodine; Picric acid; Sodium valproate; Spectrophotometric determination; p-Chloranilic acid