Solid-phase microextraction coupled with liquid chromatography for determination of β-carotene in food

Abstract

β-Carotene in vegetables and nutritional products is analyzed using solid-phase microextraction (SPME) coupled with liquid chromatography (LC) to improve the speed of analysis and to reduce the consumption of organic solvents. The relative standard deviations (RSDs) of this analytical method for β-carotene determinations in vegetables and nutritional products are approximately 10% and 5%, respectively. The amount of β-carotene was found to vary from 0.35 ± 0.05 ppm to 76.5 ± 6.9 ppm for several vegetables in Taiwan. This method was linear over the range of 0.4-40 ppm with correlation coefficients higher than 0.997. The experimentally determined level of β-carotene in nutritional products varied from 3.8 ± 0.2 ppm to 24.6 ± 1.1 ppm following SPME-LC. The recoveries of β-carotene for these measurements following SPME were all higher than 97% ± 2% (n = 3). The detection limits of β-carotene for this method were from 0.027 to 0.054 ppm. Conventional solvent extractions take approximately 4-6 h for extraction and reconcentration but SPME takes approximately 1 h. From several tens to hundreds of milliliters, organic solvents can be saved using SPME. SPME provides better analyses on β-carotene than conventional solvent extraction for nutritional products in terms of speed, precision, simplicity, and solvent consumption.