Spectrophotometric Assay of Pyridoxine Hydrochloride (Vitamin B6) in Pharmaceutical Preparations and Serum Via Arsenazo III- Cerium (III) Reaction

A simple, rapid, accurate and precise spectrophotometric method is proposed for determination of pyridoxine hydrochloride (Vitamin B6) in pure form and in its pharmaceutical preparations and serum. The method is based on the oxidation-reduction reaction between vitamin B6 and cerium (IV) ion (ceric ion), then the subsequent reaction of cerium (III) with arsenazo III reagent in acidic medium in the presence of the neutral surfactant (Triton X-100) to produce a green complex which is stable, water soluble and has a maximum absorption at 716 nm with a molar absorptivity of 1.12×10 l.mol.cm. Beer’s law is obeyed in the concentration range of 1 to 14 μg of vitamin B6 in a final volume of 25 ml. The proposed method has been applied successfully to the assay of pyridoxine hydrochloride in pharmaceutical preparations and serum. ــــــــــــــــــــــــــــــــــــــــــــــــــ ديه نيديسكوريبلل يفيطلا ريدقتلا ديارولكور ) نيماتيف B6 ( لصمو ةينلاديص تارضحتسم يف وزآ نيسرآ فشاك لعافت ىلع ً ادامتعإ مدلا III يثلاثلا مويريسلا نويا عم ا صخلمل و ةقيقد ،ةعيرس ،ةطيسب ةيفيط ةقيرط حارتقا مت ةـقفاوتم ريدـقتل دـيارولكورديه نيديسـكوريبلا ) نيماتيفلا B6 ( رضحتسم يفو رحلا هلكشب تا دلا ه يئاو مدلا لصم يفو ة . تدمتعا ةـقيرطلا ىـلع لـعافت لااو ةدسكلأا لازتخ نيب نيماتيف B6 و يريسلا نويأ ـ يعابرلا مو لعافتلا جتان ةلعافم اهعبتي مويريسلا نويأ وزآ نيسرآ فشاكلا عم يثلاثلا III يضماح طسو يف لداـعتملا يحطسـلا دشلل ضفاخلا لماعلا دوجوب ) Triton X-100 ( دقعم يطعيل ً ا رضخأ نول اذ يئاملا لولحملاب بئاذو رقتسم دـنع هصاصتما ةدش ساق ُ ت يجوملا لوطلا 716 رتيمونان صاصتملاا ةميق تناكو ةي يرلاوملا يه ة ×1.12 10 رـتل . لوـم 1 . مـس 1 و نا نيب زيكرتلا ىدم يف ريب نوناق قبط 1 و 14 نم مارغوركيام نيماتيفلا B6 يئاهن مجح يف 25 لم رـتل . يرطلا قيبطت مت ريدقت يف حاجنب ةحرتقملا ةق نيماتيفلا B6 رضحتسم يف تا يئاودلا ه مدلا لصمو ة . ــــــــــــــــــــــــــــــــــــــــــــــــــ Raeed M. Qadir and Azzam A. Mosa 29 INTRODUCTION Vitamins can be defined as essential organic compounds required in minuscule amounts (referred to as micronutrients). Vitamins mainly function as catalysts for reactions within the body. They contain no useful energy, but as catalysts, they serve as essential links and regulators in metabolic reactions that release energy from food (Bender, 1992 ).Vitamins B6 and B2 are involved in the metabolism of homocysteine, vitamin B6 serves as cofactor for cystathionine ß-synthase and cystathioninelyase, which convert homocysteine to cystathionine and then to cysteine. Vitamin B6 exists in seven forms: pyridoxine (PN), pyridoxine 5'-phosphate (PNP), pyridoxal (PL), pyridoxal 5'phosphate (PLP), pyridoxamine (PM), pyridoxamine 5'-phosphate (PMP), and the catabolite, 4-pyridoxic acid.The Pyridoxine form, is a water-soluble vitamin. It was discovered in 1934 by P. Gyorgy. (Midttun et al., 2005). Pyridoxine hydrochloride is ( 5hydroxy6methyl pyridine -3,4diyl ) dimethanol hydro-chloride (British Pharmacopeia, 2000). Many analytical methods were used for the determination of pyridoxine hydrochloride (vitamin B6), these methods included colorimetric, the method is based on the measurement of the blue product results from the reaction between pyridoxine hydrochloride and 2,6-dichloroquinonechloroimide (John, 1941). The diazotized p-aminoacetophenone (Elmer et al., 1945) also was described for colorimetric determination of pyridoxine hydrochloride. An orange species formed when pyridoxine hydrochloride is treated with diazotized dapsone and sulphanilamide in a mixture of trichloroacetic acid and sulphuric acid at room temperature (Sane et al., 1983). A spectrophotometric method is also described for the determination of pyridoxine hydrochloride (vitamin B6) by flow injection analysis depending on the reaction of vitamin B6(pyridoxine) with N,N-diethyl-p-phenylenediamine after oxidation by potassium hexacyanoferrate (III) (Clezio and Orlando, 1999). Another spectrophotometric method is also described for the determination of pyridoxine hydrochloride based on the reaction between pyridoxine hydrochloride and 1,10-phenanthroline in the presence of ferric nitrate, the reddish brown colored product shows maximum absorption at 510 nm (Kuchekar et al., 2002). A micellar reversed-phase liquid chromatographic procedure was also developed for the determination of B6 group vitamins, i.e. pyridoxine, pyridoxal and pyridoxamine, in human serum (Josep et al., 2004). Arsenazo III reagent gives sensitive and selective reactions with several cations, such as reaction with cerium (III) ion in the presence of cerium (IV) ion. This reaction can be used in the determination of some organic compounds which have the ability to undergo oxidation reaction with cerium (IV) ion (Al-Abdaly, 2005). Pyridoxine Hydrochloride, C8H11NO3. HCl