Revue Roumaine de Chimie, 2006, 51(5), 439–445 Dedicated to the memory of Professor Maria Brezeanu (1924–2005) SIMULTANEOUS DETERMINATION OF VITAMIN E AND VITAMIN H 1 BY FIRST DERIVATIVE SPECTROMETRY IN AN OINTMENT PREPARATION Irinel Adriana BADEA, Luminiţa VLĂDESCU and Arabela PATRICHI Department of Analytical Chemistry, Faculty of Chemistry, University of Bucharest, 2-14 Bv. Regina Elisabeta, 030018 Bucharest, Roumania e-mail: irinel_badea@yahoo.com Received January 19, 2006 Sensitive and selective first derivative method for the determination of Vitamin E and para-aminobenzoic acid in either pure mixture or in its pharmaceutical preparation is described. The method proposed is linear in the concentration range of 0.02–0.1 mg.mL –1 for Vitamin E and 0.005–0.03 mg.mL –1 for para-aminobenzoic acid, while being precise and accurate. The LODs for the determination of Vitamin E and para-aminobenzoic are 0.086 µg.mL –1 and 0.011 µg.mL –1 , respectively. The derivative spectrometric method proposed is absolutely novel and very useful for the in-process control of mixtures made by mixing Vitamin E, as a major compound, para-aminobenzoic acid, as minor ones, and common excipients used for ointments preparation. The results match up those methods reported in the literature. INTRODUCTION Vitamin E (VIT E), a fat soluble chemical found in the diet in varying amounts, is a potent antioxidant 1-2 and has, at skin level, a nonenzymatic activity. Semi-solid preparations for cutaneous application containing Vitamin E (in form of α-Tocopheryl acetate, as it is very stable to UV action) as a major active compound are used to reduce skin photo damage. 3 Para-aminobenzoic acid (PABA) is a non-protein amino acid sometimes referred to as vitamin H, but it is neither a vitamin nor an essential nutrient for humans. 4 Para-aminobenzoic acid is important to skin, hair pigment, and intestinal health. Used as a sunscreen, it can also protect human beings against the development of sunburn and skin cancer from excessive ultraviolet light exposure. Para-aminobenzoic acid is a filter and can be incorporated up to 15% in sunscreen products 5 which are used commonly to prevent and treat sunburns and, with vitamin E, it is often applied to other burns. The development of ointments containing both Vitamin E and para-aminobenzoic acid requires rapid, precise and accurate analytical methods for the assessment of both compounds during the in-process control. A judicious investigation of the literature has revealed that no spectrometric and chromatographic method has been reported for the simultaneous determination of both compounds. Assays of Vitamin E are usually made by HPLC, 6–13 GC 14 and spectrometric methods, 15 while for para-aminobenzoic acid by spectrometric, 16–17 chromatographic (HPLC, CZE, GC, TLC) 18–22 and electrometric 23–25 methods. The official monograph described in pharmacopoeia recommends for PABA a potentiometric method 26 while for VIT E a gas chromatographic method. 27 This paper reports a rapid, sensitive and highly selective UV derivative spectrometric method used for the simultaneous determination of Vitamin E (VIT E) and acid para-amino benzoic (PABA). Thus, a rapid precise and accurate derivative spectrometric method for the assay of both compounds is proposed. This method is absolutely novel and very useful for the in-process control of mixtures made by mixing VIT E, as major compound, PABA, as minor ones, and common excipients used for ointments preparation. Such ointment is a medicinal product manufactured in a pharmacy based on a recipe and intended to be used by people who work in hard industrial conditions for their own skin protection.