A COMPARISON OF HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY AND SPECTROPHOTOMETRY TO MEASURE CHLOROPHYLL IN CANOLA SEED AND OIL

There are several methods available to measure chlorophyll in canola o il and seed, and these will not necessarily yield the same results and should not be used interchangeably. Total chlorophyll was determined for samples of canola seed and commercial canola oil by recognized spe ctrophotometric methods and by high-performance liquid:chromatography (HPLC). The HPLC method, which summed all chlorophyll related pigments detected, found approximately 1.4 times more total chlorophyll per sa mple than did the spectrophotometric methods. The spectrophotometric m ethods are calibrated with only chlorophyll a and underestimate other chlorophyll pigments, which have lower extinction coefficients and dif ferent absorption maxima. The HPLC method detects each pigment at its absorption maxima and applies the appropriate absorptivity factor. Car e must be taken when comparing results obtained by different methods. There appears to be a need for a standardized method of chlorophyll pi gment measurement by HPLC.