0000000000793576
AUTHOR
Vicente Peris Martinez
Phenolic and acetylenic metabolites from Artemisia assoana
Abstract Nine flavones, three coumarins, two flavone glycosides, p-hydroxyacetophenone and methyl caffeate have been isolated from the aerial parts of Artemisia assoana. Six diacetylenic spiroketal enol-ethers, a mixture of n-alkyl p-coumarates and a new phenylpropanoid metabolite, sinapyl alcohol diisovalerate, have been isolated from root extracts of the same plant. 1H and 13C NMR spectra of some of these compounds are given and taxonomic aspects are discussed.
Spectrophotometric determination of fluoride in fluoride-bearing minerals after decomposition by fusion with sodium hydroxide
The decomposition of highly insoluble minerals (fluorspar and cryolite) by fusion with molten alkali-metal hydroxides is studied. The introduction of additives such as aluminium compounds or sodium peroxide to obtain total liberation of fluoride from calcium fluoride samples, is tested. The fusion is done in a silver crucible with a Bunsen burner. The cooled melt is easily soluble, giving solutions suitable for spectrophotometric fluoride determination by the Zr(IV)-fluoride-Erichrome Cyanine R method.
Determination of fluoride after direct separation from acid medium by collection of its volatile compounds
A method is proposed for determination of fluoride by separation in acid medium followed by ion-selective electrode measurement. The separation is done at temperatures up to 200 °C, without any previous treatment of the sample, in a PTFE reactor designed to ensure the complete absorption of volatile fluoride compounds. The distillation variables (temperature, time and acid concentration) have been optimized and the interference of other various species in the separation step has been studied. The method has been applied to geological samples. The results obtained are statistically satisfactory.