HPLC-MS analysis of the green food colorant sodium copper chlorophyllin

Five commercial samples of sodium copper chlorophyllin, a green food colorant, were analysed by high-performance liquid chromatography (HPLC) using diode-array detection (DAD) and mass spectrometry (NIS). Some of the constituents were identified using authentic standards, whereas others were identified tentatively based on their absorption spectra and mass data. The composition of three of the samples was very similar, whereas the other two were quite different. In the three former samples, the three largest peaks could be assigned to Cu chlorin e(6), CU chlorin P-6, and Cu isochlorin e(4). In one of the two other samples, these three compounds were also among the largest peaks, whereas Cu chlorin e(6) was a small peak in the last sample and Cu chlorin p(6) was absent altogether. Porphyrins were also present in the samples, while except in one of the samples chlorins derived from chlorophyll b were largely absent. (c) 2007 Elsevier Ltd. All rights reserved.