Figure 1: HPLC elution profiles after fractionation with aluminium oxide. Upper panel: chromatogram of the alumina column fraction 5 from the methanol : petroleum ether extract of water suspended chloroplasts. Red and black chromatograms refer to elution profiles detected at 290 or 255 nm, respectively. In the lower panel, black downward arrow indicates the elution of the PQ oxidized form (retention time of 19.2 min); the peak of the oxidized form at 255 nm is decreased upon reduction. Red upward arrow indicates the elution of the PQ reduced form (retention time of 8.1 min) whose peak at 290 nm becomes visible upon reduction.