Problematical Solvent System Compositions

Sample solntions Reflnx with methanol + ethyl acetate + tolnene, filter, concentrate With methanol nltrasonic bath, centrifnge 100 mg DE/ml Dissolve in water, extract with HCl-addified CHCI3, org. phase = 0, dissolve R in CHCI3 500 mg DE/ml 

Sorbent Prescribed Silica gel G Used TLC silica gel 60 F254 20 X 20 cm (Merck 1.05715) TLC silica gel 60 F254 20 X 20 cm (Merck 1.05715) TLC silica gel 60 F254 10 X 20 cm (Merck 1.05729) Used transversely 

Solvent system Ether+ methanol (90 + 10) Toluene -1- ethyl acetate (50 -1- 20) Acetone -1- water -1- ammonia solution cone. (45 -1- 3,5 -1-1,5) 

Derivatization Vanillin-phosphoric Vanillin-phoshoric Detection at UV 

CHCs must always be treated as hazardous solvents  

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If several plates have to be developed with the same solvent system in one day, the total amount required can be prepared in one batch provided that the solvent compositions are uncritical. This is recommended even for quantitative work in order to maintain reproducible hRf values. Critical solvent systems are discussed in Section 4.1.3 Problematical Solvent System Compositions . 

We have developed an analogous, but more robust system which is not necessarily constraint by the aforementioned limitations. The obvious extension has been to couple an affinity-based separation with mass spectrometry. Hutchens et al. have shown that affinity probe surfaces can be ust to capture specific protein ligands allowing detection by laser desorption mass spectrometry (. The limitations to their technique have been that the surface area for ligand capture is quite small and salt (or detergent) contaminants are still problematic. Perfusive affinity resins, on the other hand, provide a tremendous surface area for binding. The nature and composition of the solvents required for affinity chromatography, however, are not directly compatible with mass spectrometric analysis. 

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