Ultrasensitive determination of trans-beta-carotene in rat and beef liversby means of high-performance liquid chromatography coupled with thermal lens detection

Hyphenated high-performance liquid chromatography (HPLC)-thermal lens spect rometry (TLS) was demonstrated as a method capable of selectively profiling carotenoids in animal livers and suitable for ultrasensitive determination of trans-beta-carotene in the same tissues. The new approach, HPLC-TLS, a first choice method when studying the tissues containing minute quantities of trans-beta-carotene such as in the case of rat liver, also proved useful in the analysis of beef liver. Due to high sensitivity of the HPLC-TLS met hod, there is no need for enrichment of liver extracts; in fact, multifold diluted extracts can be analysed directly which not only preserves caroteno ids from structural transformations, but also minimises the risk for contam ination of the stationary phase. Furthermore, both the calibration in a mat rix-matched medium and standard addition method have thus become unnecessar y. Reliable determinations of trans-beta-carotene in rat and beef livers (r ecoveries 98.0 and 99.8%) were obtained by calibration in the mobile phase within the linearity range 1-130 ng ml(-1). In addition, favourable detecti on limits (0.39 and 0.49 ng ml(-1)), precision of determination (2.8-7.2%) and the selectivity evidenced in the presence of multifold molar excess of vitamins A and E, cholesterol and lecithin, confirm the suitability of the method. The HPLC-TLS approach can be successfully applied in studies concer ned with the biotransformation of beta-carotene which are of both scientifi c and public health interest. (C) 2000 Elsevier Science B.V. All rights res erved.