Methanol fractionation

Solvent extraction procedures involve collection of sample by an appropriate device and subsequent immediate placement into a borosilicate glass vessel, which contains a known quantity of ultrapure methanol. The bottle is then transported to the laboratory at 4°C, and the methanol fraction analyzed by purge-and-trap gas chromatography (or a similar procedure). 

Suppose a buffer system in CE consists of methanol/buffer 10 90 (v/v). When the methanol fraction is selected as factor in a robustness test, the buffer fraction serves as adjusting component to sum the fractions to 1. 

Concurrently, Gordon and co-workers (1973) reported another important phenomenon benzene extracts of airborne particles collected in the Los Angeles Air Basin had 100-1000 times the cell transformation activity of that which could be attributed to the measured levels of known PAHs in the samples. Strikingly, the polar (methanol) fraction of these extracts, which amounted to only 3% of the total mass in the sample of ambient particles, had an activity equal to the neutral benzene extract that contained the remaining 97% of the PAHs (including BaP). 

Similar investigations with the related species Tegenaria pagana and Tegenaria domestica (Trabalon et al., 1997) determined that males of both species reacted to attractive females with longer contact times compared with that for unattractive or solvent-washed females. The response was species specific, and when pentane extracts were partitioned between pentane and methanol, most of the activity was found in the methanol fraction. The methanol fractions contained fatty acids and their methyl esters and showed quantitative differences between the two physiological states of the females with respect to myristic acid, methyl palmitate,... 

Valdes extracted with ether. He partitioned the dried extract between hexanes and 90 percent aqueous methanol, saving the polar components in the methanolic fraction. 

Lyophilized, pulverized leaves (5.35 kg) of S. divinorum were extracted with ether. The nonpolar components were removed from the concentrated extract through partition between hexanes and 90% aqueous methanol. The dried methanolic fraction was crudely purified by silica gel flash column chromatography (hexanes-ethyl acetate 2/1). Further purification of the biologically active fractions by additional silica gel flash column chromatography (methylene chloride-methanol 20/1) followed by repeated recrystallization yielded pure divinorin A (1) (1.2 g) and B (3) 50mg. 

In a typical experiment, a Fischer Porter 2.5 x 25 cm column containing 55 g of silica gel (70-230 mesh) which had been treated with 2.75 mL of water, was equilibrated with the eluting solvent, hexanes/ethyl acetate (2/1). Five hundred milligrams of the methanolic fraction was adsorbed on 5 g of silica gel and carefully poured on the preequilibrated column. The eluting solvent was then forced (using nitrogen pressure) through the column at the flow rate of 25-35 mL/min and 100 mL fractions were collected. 

Use the of value derived above for the 0 to 20% methanol range. Note that in reality, erf may be somewhat larger at this higher methanol fraction. Insertion of of = 4.2 into Eq. 9-35 with a = 1 andf, = 0.3 yields ... 

Pooled 0- to 24-h and 0- to 168-h human urine samples were concentrated on an Oasis HLB 3.0-ml cartridges. The cartridge was loaded with pooled urine (3 ml) and washed sequentially with water containing 0.1 % acetic acid (2x3 ml, pH 3.2) and methanol (2x3 ml). Liquid scintillation counting of the water and the methanol extracts showed quantitative recovery of radioactivity in the methanol fractions. The methanol extracts were combined, evaporated to dryness under a stream of nitrogen, and dissolved in HPLC mobile phase. 

Function Condense overhead vapors from methanol fractionation column ... 

The plant material was extracted according to the procedure in Figure 1. The ethanol extract [2] (Figure 1) exhibited total inhibition of feeding against the cotton boll weevil at levels of 10, 25, and 50 mg (Table I). Further fractionation of the ethanol extract [2] showed no abatement of this antifeedant activity in either the CHClj [3] or the aqueous fraction [4] with %T/C values of less than 12% at the 10-50 mg dose levels as indicated in Table I. Further fractionation (Figure 1) and bioassay (Table I) showed that the methanol fraction [6], and the CHC /ethanol fraction [7] demonstrated excellent antifeedant activity. 

Subirats, X., Bosch, E., and Roses, M. Retention of ionisable compounds on high-performance hquid chromatography XVII estimation of pH variation of aqueous buffers with the change of the methanol fraction of the mobile phase. J. Chmmatogr. A. 2007, 1138, 203-215. 

Extraction with 95% ethanol. Concentration, redissolution in 50% methanol Fractionation of extracts in PVP column... 

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