Observations on some of the problems associated with the analysis of carotenoids in foods by HPLC

Abstract

There is considerable current interest in the influence of certain foods on human health. In the study of the relationship between nutrient intake, nutritional status and morbidity, the need for accurate qualitative and quantitative data on the nutrients in these foods has become increasingly important. β-Carotene has attracted particular attention not only because of its nutritional role as a vitamin A precursor but also because of its antioxidant potential. More recently interest has been extended to the possible importance of other naturally occurring carotenoids. Their measurement in natural products involves extraction and chromatography with organic solvents. The potential for loss during sampling, extraction and saponification has been recognised, although definitive methods have yet to be described satisfactorily. It is however often overlooked that the response of carotenoids may be affected by artefacts produced during chromatography. Two areas in particular are (i) the reaction between carotenoids and metal surfaces with particular reference to stainless steel frits and (ii) the reaction between carotenoids, injection solvents and the mobile phase. These may result in peak distortion and the production of artifacts which can lead to misinterpretation of the chromatogram and the production of erroneous and unreliable data. Studies to identify the problems, and preliminary conclusions on the way they may be overcome are reported.