Photoacoustic spectroscopy and optothermal window as analytical tools to quantitate carotenes in margarines

Photoacoustic spectroscopy (PAS) and optothermal window (OW) with a cw Ar ion laser used as a radiation source at 476.5, 488 and 496 nm were applied to quantify total carotenes (TC) in margarines. Both techniques, being rapid and extremely simple, allow for direct measurement without any pretreatment of the sample. The PAS has proven precise and sensitive enough to allow quantitation of TC in margarines containing 1–9 mg TC/kg, in applications such as the quality control of intermediate and final products. The sensitivity of OW is lower than that of PAS but the approach can still be used for quantitation of TC in margarine matrices at much higher concentrations.