The fluorescence spectra of bright-leaf tobacco have very definitive characteristics. The cured leaf had a prominent fluorescence peak at 525 mµ. The turgid and desiccated leaves had major and minor fluorescence peaks at 465 mµ and 480 mµ respectively. The ∆f values increased for the turgid, desiccated, and cured leaves in this sequence. Measurements made on the immature, mature, and overmature leaves·show definite differences in ∆f values. The ∆f values increased as the tobacco leaves became more mature. The three varieties tested show definite differences, 101 CR, Hicks, and C 139 had higher ∆f values respectively. The cured samples gave the best index of variety differences. There were two very encouraging differences in this experiment. First, C 139, a discount variety, stood out from the other varieties according to the ∆f values. This variety had the highest average ∆f value of all three. Second, the B selection of all three varieties (with the one exception of 101 CR-B-cured) had a higher ∆f value than did selection A. This seems to indicate that tobacco of low “quality" has a high ∆f value, that is, a low ∆f value is desirable in mature tobacco. It must be pointed out, however, that the evidence presented here is not conclusive by any means. Further studies are being made of the florescence excitation spectra of the intact leaf. Intensive consideration are being given to the fluorescence spectra, and fluorescence excitation spectra of the major individual leaf compounds in their pure state. These studies will permit qualification of the optimum absorption band of the tobacco leaf, Other studies, such as spectrophotometric analysis in the ultraviolet, visible, and infrared, offer promising results in evaluating non-destructively tobacco leaf properties related to quality, Hence, the final objective assay of leaf quality may depend on a combination measurements, of which spectroflurometric analysis could be one.

(Full article published with kind permission from "Tobacco International")