LIQUID-CHROMATOGRAPHIC DETERMINATION OF CAROTENOIDS USING DUAL-BEAM CONTINUOUS-WAVE LASER THERMAL LENS DETECTION

Chromatographic separations of carotenoids were carried out with a conventional column (4.6 mm i.d.) with an analytical flow cell (10 mm path length) and a microbore column (1.0 mm i.d.) with a microcell (3 mm path length) using dual-beam thermal lens detection. The technique was compared with conventional UV-visible spectrophotometry under static conditions and with both chromatographic systems. The comparison was made in terms of signal-to-noise ratios and detection limits. The linear absorbance range was from 10(-3) to 10(-5) and from 10(-2) to 10(-4) with the analytical cell and the microcell, respectively. For three carotenoids, the minimum observable absorbance at the top of the peak was 2.4 x 10(-5) and 1.1 X 10(-4) in conventional and microbore chromatography, respectively.