Photodiode array , chlorophyll

Post-column detection of chlorophyll derivatives is often accomplished by ultraviolet and visible spectroscopic techniques, which take advantage of the strong electronic absorption spectra of these pigments (units F4.3 F4.4). While these methods have enjoyed wide application (Schwartz et al., 1981 Khachik et al., 1986), a major advance was made with the introduction of photodiode array (PDA) detection. Multichannel photodiode array detection allows for simultaneous monitoring of multiple wavelengths, resulting in the generation of online electronic absorption spectra of a compound as it elutes from the HPLC column. Because of the uniqueness of electronic absorption spectra of individual chlorophyll derivatives, these techniques have enjoyed extensive application for tentative identification of components from complex mixtures and extracts... 

Identification of chlorophylls and their derivatives can be made more efficient by use of a photodiode array detector which allows collection of on-line spectra. However, this... 

Fig. 11 Chromatogram of chlorophylls, chlorophyll derivatives, and carotenoids extracted from spinach leaves and analyzed by HPLC with a photodiode array detector. Chd = chlorophyllide, Pb = pheophorbide, Chi = chlorophyll, Po = pheophytin. (From Ref. 99.)...

Schoefs et al. [769] extended the above methods to include the analyses of chlorophylls and protochlorophylls extracted from kidney bean, wheat, and cucumber seeds along with the cis-trans carotenoids. A C g colunm (A = 437run) and a complex 23-min 100/080/20 (70/30 acetonitrile/methanol)/DCM gradient gave adequate separation of 23 compounds, although not all pairs were baseline resolved. To address this problem, a photodiode array detector was used to deconvolve and identify overlapping peaks. 

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