RAPID-DETERMINATION OF CHLOROPHYLLS IN VEGETABLE-OILS BY LASER-BASED FLUOROMETRY

The presence of chlorophylls in vegetable oils is considered undesirab le due to their adverse effects on oxidative deterioration, bleachabil ity and hydrogenation. The usual methods for determination of chloroph ylls in vegetable oils are absorption spectrophotometry, fluorometry a nd liquid chromatography using fluorescence. detectors. This paper out lines a fluorometric method using a laser as the excitation source. Th e chlorophylls in crude palm oil, rapeseed oil, soya bean oil and oliv e oil were determined directly by laser-based fluorometry using (a) a helium-neon laser (632.8 nm, 5 mW) as the excitation source and an opt ical-multichannel analyser (OMA) with an intensified diode array as th e detector, and (b) a helium-neon laser and a photomultiplier tube as the detector. The method is especially suitable for the detection of c hlorophylls in crude palm oil since no pre-extraction step is required . The levels of chlorophyll measured in vegetable oils using the laser technique was also compared against values obtained by conventional s pectrophotometric methods. The simplicity and rapid quantification of laser based fluorometry suggest that this technique can be readily app lied to the detection of a wide variety of fluorescing species in vege table oils.