Ethyl silicate, analysis

Figure 11.1a [1] shows a schematic representation of a micropreparative thin-layer chromatogram obtained on a 0.5-mm Florisil (magnesium silicate) layer prewetted with benzene of a crude extract, i.e., containing coextracted plant oil obtained from Heracleum moelendorfi fruit. The initial band of extract was washed with benzene and then separated by continuous development with ethyl acetate in benzene [1]. As seen from the fraction analysis presented in Figure 11.1b, small quantities of pure bergapten and xanthotoxin can be isolated in this maimer. 

A number of techniques have been developed for the trace analysis of silicones in environmental samples. In these analyses, care must be taken to avoid contamination of the samples because of the ubiquitous presence of silicones, particularly in a laboratory environment. Depending on the method of detection, interference from inorganic silicate can also be problematic, hence nonsilica-based vessels are often used in these determinations. Silicones have been extracted from environmental samples with solvents such as hexane, diethyl ether, methyl isobutylketone, ethyl acetate, and tetrahydrofuran (THF)... 

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