This work describes a comparative qualitative and quantitative chemical analysis of Maytenus ilicifolia and Maytenus robusta (Celastraceae), extracts by high-resolution gas chromatography (HRGC), using external standards as the method of determination and thin layer chromatographic (TLC). The results show that both plants have a similar chromatographic profile. However, M. robusta exhibited about three times higher concen tration of triterpene friedelin than M. ilicifolia.

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As is known for several years (1 to 4 ) the absorption and emission bands of ZnS type crystals activated by manganese show fine structure. The origin of this splitting is still controversial. McClure (2) explained the structure as zero-phonon lines due to transitions within both single Ban2+ ions and Mn2+ pairs split by the tetrahedral electric fields of the crystals. Brumage et al. for Mn-Mn pair transitions. The decay time of the luminescence being 6 function of the oscillator strength one should expect different decay times for lines due to single ions and pairs respectlvely. On the other hand lattice vibrations also reduce the symmetry of the crystal field and should give rise to small differences of the oscillator strength of zero-phonon lines and phonon-coupled lines,We measured the time constants of the build-up and the decay of luminescence under excitation by visible radiation a n d by electric fields (electroluminescence) respectively with high spectral resolution.The materials we used were ZnS phosphors and ZnS crystals doped with amounts between and ~X I O -~ g Mn/g ZnS in photo-