Development of an Analytical Method for the Combined Determination of Water-Soluble Vitamins and Minerals Through High-Performance Liquid Chromatography–Inductively Coupled Plasma Atomic Emission Spectrometry Hyphenation
The capabilities of inductively coupled plasma atomic emission spectrometry (ICP-AES) for the determination of water-soluble vitamins after high-performance liquid chromatography (HPLC) separation have been evaluated for the first time in the present work. Thanks to the multielemental capability of ICP-AES, it has been possible to develop a method for the joint determination of several water-soluble vitamins and minerals. The vitamin chromatograms were obtained by plotting the carbon corrected emission intensity against time. Meanwhile, minerals were determined through the measurement of the emission intensity at their characteristic wavelengths. The established method was applied to the determination of thiamine, riboflavin, pantothenic acid, nicotinamide, ascorbic acid, Cr, Mo, Se, Mn, Zn, Fe, Mg, Ca, and K in multivitamin complexes. Good linearities were obtained, with correlation coefficients above 0.999 for all the vitamins and metals. The detection limits using ICP-AES for vitamins were lower than 10 mg L−1 except for biotin (18 mg L−1) and ascorbic acid (35 mg L−1). Moreover, the limits of detection for metals ranged from 0.3 mg L−1 for K and 0.02 mg L−1 for Mo. Even though the ICP is less sensitive than PDA and MS for vitamin determination, the HPLC-ICP-AES allows determination of vitamins and minerals in a period of time not much higher than that required for the simple determination of the minerals, and it is less sensitive to interferences in trace quantities.
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The authors would like to thank to the Spanish Education Ministry (Projects PETRI95-0980-OP and CTQ2009-14063) and to the Vicerrectorado de Investigación of the University of Alicante for the financial support. E.P. also thank the Generalitat Valenciana for the FPI grant.