Thermal lens spectrometry in food analysis and environmental research

The inherent high sensitivity of the TLS enables detection of various pigme nts such as chlorophyll or various carotenoids at sub ng/ml concentration l evels. This was exploited for HPLC-TLS determination of characteristic majo r and minor carotenoids and chlorophylls in various species of marine phyto plankton. In this work the TLS detection was used in combination with a lin ear gradient HPLC for the first time. While the gradient elution provides t he required selectivity of analytical procedure, the high sensitivity of TL S detection facilitates the determination of representative compounds, and adds to the accuracy of the discrimination between different phytoplankton species. For determination of fatty acids, a novel TLS detector, which oper ates at CO laser wavelengths, was developed for the needs of HPLC analysis, and Bated against the refractive index detector (RID). The HPLC/IR-TLS det ection scheme has demonstrated sensitivity comparable to the RID detector ( LOD = 0.04%) and substantial improvement in selectivity since it is capable of discriminating between fatty acids and interfering compounds like octan ol, decanol and other compounds which do not absorb in the carbonyl band re gion.