Copper chlorophyll in olive oils: identification and determination by LIF capillary electrophoresis

The green colour of virgin olive oils is due to chlorophyllic pigments, chlorophylls, pheophytins, pyropheophytins. The natural chlorophyllic pigments are totally absent in refined olive oil. Sometimes the colour of this oil is obtained by synthetic chlorophyll pigments as copper chlorophyll derivatives. The analysis of the pigment responsible for oil colour is of great importance, since it can be used to prove the authenticity and quality of virgin olive oils. A capillary zone electrophoresis (CZE) method, with LIF detection was developed to separate copper chlorophyll from others chlorophyll pigments and to determinate it in the olive oil. The separation occurs in a short time, less than 10 min, The elution time of copper chlorophyll is different enough of those of natural pigments. The standard deviation of the migration times of copper chlorophyll peak is RSD%=0.55. Copper chlorophyll peak was identified and quantified by external standard method. The limit of detection with a 3:1 signal-to-noise ratio was 5 μg/kg. Our CZE procedure is rapid and sensitive.