Fluorometric determination of chlorophylla in the presence of pheopigments: effect of the half-value width of the excitation beam

The ratio of fluorescence intensities for chlorophylla before and after acidification is dependent upon the excitation wavelength and upon the spectral band width of the exeitation beam. Optimal conditions for differentiating between chlorophylla and pheopigments occur when the excitation wavelength is in the range of 435 to 440 nm and the half-value width of the beam is less than 6 nm. The reduced sensitivity brought about by the low amount of energy reaching the sample under these conditions can be compensated for by minor modification of other instrumental parameters.Contribution N. 665 of the biology Division, Commission of the European Communities.