Quantitation of copper chlorophylls in green table olives by ultra-high-performance liquid chromatography with inductively coupled plasma isotope dilution mass spectrometry.

•UHPLC-ICP-ID-MS was first used to measure copper chlorophylls.•Most chlorophylls in bright green table olives were complexed with copper.•Bright green table olives contained total elemental copper above natural abundance.•ICP-ID-MS provides quantitation of copper chlorophylls without using reference materials.•High total elemental copper and copper chlorophyll content may be achieved by addition of copper salts.