Preparative scale HPLC

Cuscutic resinoside A (1 tetradecanoic acid, (115)-[[6-deoxy-3-(9-(6-deoxy-a-L-mannopyranosyl)-4-0-[(2/ ,3R)-3-hydroxy-2-niethyl-l-oxobutyl]-a-L-nianno-pyranosyl]oxy]-intramol. l,2 -ester) was obtained from the ethyl acetate-soluble fraction of a methanol extract prepared from the seeds of Cuscuta chinensis Lam. The purification of this compound employed a combination of column and preparative-scale HPLC. The structure was deduced from spectroscopic evidence and acid hydrolysis 14). The degradative process gave convolvuUnolic acid, nilic acid, and L-rhamnose. The sugar components were identified by GC analysis after being converted to their thiazolidine derivatives. This disaccharide has a unique macrocyclic lactone, which is placed between C-1 and C-2 of the first rhamnose moiety. 

Additional Preparative-Scale HPLC Separations. After mutagenesis assessment of the HPLC fractions from the initial preparative-scale separation just discussed, those fractions containing mutagenic constituents are further separated on HPLC by employing the following strategy For example, if the mutagenic constituents were found to be in Fraction D from an initial reverse-phase HPLC preparative-scale separation, that is, a mobile-phase composition of 25 water 75 acetonitrile, a... 

Preparative-Scale HPLC Separations. Results of the analytical-scale HPLC separations are used to develop an approach in the scale-up of the HPLC separations for the preparation of subfractions of the residue organics in quantities suitable for mutagenesis testing and compound isolation. If the analytical-scale separation results indicate the... 

Isolation of Mutagens. Applying the general preparative-scale HPLC separation procedure outlined in the previous section (Step I),... 

Structure Macroporous polystyrene-divinylbenzene nonpolar adsorbent, 62-177 pm particle size Analytical Properties Used mainly in preparative-scale HPLC stable over entire pH range (1-13) sometimes difficult to achieve column-to-column reproducibility due to packing the irregular particles relatively lower efficiency than alkyl bonded phases particles tend to swell as the organic content of the mobile phase increases Reference 1... 

Fritz and co-workers (F5) described the use of reversed-phase HPLC for the isolation of protected oligonucleotide intermediates in the stepwise synthesis of deoxyribonucleotides. They report that the use of reversed-phase preparative scale HPLC reduces the time required for synthesis of oligonucleotides by 30%. In addition, they report on the RPLC separation of unprotected S -hydroxylated oligonucleotides. 

It was decided that the most efficient method of identification was to couple succinic anhydride with the drug substance and isolate the peak of interest by preparative-scale HPLC. A solution of the drug substance was treated with dimethylaminopyridine and succinic anhydride. The resultant solution was stirred at room temperature for 48 hours. The reaction mixture was partitioned between ethyl acetate and water, and the aqueous layer was then treated with IN HC1. The two layers were shaken well, and the aqueous layer was removed. The organic layer was then washed with water, saturated sodium chloride solution, dried with magnesium sulfate, and concentrated by evaporation to afford a clear colorless oil (1.81 g). A suitable preparative HPLC method using a volatile mobile phase of 0.1% formic acid in water/ methanol was developed, and the crude reaction mixture was purified by preparative-scale HPLC. The solution was concentrated by evaporation and the water was removed from this solution by freeze-drying to afford a white lyophilate (40 mg). 

Comparison of Analytical Scale HPLC with Preparative Scale HPLC... 

A novel UV detector has been reported for preparative scale HPLC in which the solvent is allowed to flow over a supporting plate where it assumes the thickness characteristic of the flowing liquid film. The UV radiation falls on the film a little below the delivery tube from the column. The detector has been used for concentrations from lmg to 30 g and for flow rates from 1ml min-1 to 400 ml min-1. 

Some Special Considerations for Preparative-Scale HPLC in Natural Products Chemistry... 

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