Talanta 43 (1996) 1555-1563 Talanta Determination of fat-soluble vitamins in yogurt by HPLC with electrochemical detection M.M. Delgado Zamarrefio *, A. Sanchez Perez, M. Sanchez Rodriguez, M.C. Gomez Perez, J. Hernandez Mendez Dep~rimmto de Quimica Analitica, Nuttkidn y Bromatologia, Facultad de Cirncias Quimicas. ilnicersidud de Sulamanca. 37008 Salamunca, Spain Received 13 November 1995; revised 21 February 1996; accepted 18 March 1996 Abstract A method employing HPLC with electrochemical detection for the rapid and simultaneous determination of vitamins A, D, and E is described. The method uses a C-18 reverse phase column and 2.5 mM HAcO-NaAcO in methanol-water (99:1, v/v) solution as the mobile phase. The compounds are quantified using amperometric detection with a glassy carbon electrode at a potential of + 1300 mV (vs. Ag/AgCl) and the results are compared with thoseobtained using UV detection at a wavelength of 280 nm. The method was successfully applied to the analysis of vitamins A, D, and E in yogurt samples. After saponification, fat-soluble vitamins were extracted and the methanolic solution of the extracts was injected directly into the chromatographic system, avoiding the clean-upstepwhich is necessary when no electrochemical detectionis used.Good recovery percentages were obtained. KeyworcL~: Electrochemical detection; High performance liquid chromatography: Vitamins A, D, and E: Yogurt 1. Introduction milk is of major importance because dairy foods play a vital role in human nutrition. In recent years, a great deal of research has been devoted to developing sensitive, selective, rapid and reliable methods for the analysis of fat-soluble vitamins in foods [l] because deficien- ties of these vitamins cause serious nutritional diseases. The analysis of vitamins A, D, and E in * Corresponding author. Over the past few years, the consumption of yogurt has increased largely because of the nutri- tional and therapeutic advantages involved; it fa- cilitates the assimilation of proteins, lactose and lipids and promotes a balanced intestinal flora [2]. Methods have been described for the analysis of fat [3], inorganic acids [4], lactose [5,6] carbo- hydrates [7], preservatives [g-10], ascorbic and dehydroascorbic [l l] acid and n-dicarbonyl com- 0039.9140/96/$15.00 C 1996 Elsevier Science B.V. All rights reserved PIZ SOO39-9140(96)01939-X