Medium pressure liquid extraction

The reaction mixture is cooled, diluted with 100 mL of sat. aq NaCI and extracted with four 50-mL portions of Ei,0. The combined ethereal extracts are washed with 50 ml. of sat. aq NaCI, dried, filtered and concentrated to a volume of a few milliliters. 20 ntL of petroleum ether arc added to precipitate the soluble salts. The mixture is filtered through a silica gel column (petroleum ether)and purified by medium-pressure liquid chromatography yield 360 mg (65%). 

The synthesis of 6-hydroxy fluvastatin with M. rammaniana DSM 62752 gave high conversion (>95 %) in shake flask culture on 400 mL scale with 0.1 g L of fluvastatin as well as on 22 L scale in a Wave bioreactor-fed batch process at a final substrate concentration of 0.4 g L Instead of the partial purification by a second solid-phase extraction described above, 6-hydroxy fluvastatin can be obtained in high purity ( 95 %) by, for example, preparative medium-pressure liquid chromatography (MPLC) on RP18 silica gel. ... 

Reaction of benzaldehyde with Bu AlTeBu (typical procedure) In a flame-dried flask equipped with an Ar inlet and a rabber septum was placed n-BuTeTeBu-n (185 mg, 0.5 mmol). After BU2AIH (1 N in hexane, 1 mL) was added under Ar, the solution was stirred at 25°C for 1 h and then 2 mL of THF was added. The solution was cooled to -23°C and 2 mmol of benzaldehyde and 0.5 mL of EtjAlCl (1 N in hexane) were injected. The mixture was gradually warmed to 25°C, stirred for another 1 h and poured into saturated NH Cl solution. Products were extracted with EtjO (3X30 mL), dried over MgS04 and concentrated in vacuo. Medium pressure liquid chromatography (MPLC) of the residue gave pure Te-butyl tellurobenzoate in 71% yield (205 mg) in a hexane/Et20 (100 1) fraction. 

Rock samples were extracted using methylene chloride and a Soxhlet apparatus and the resulting extract was further fractionated by a semi-quantitative SARA separation. After asphaltenes were removed from the concentrated extract by precipitation with excess pentane, the pentane soluble portion of the sample was separated by medium-pressure liquid chromatography (MPLC) using a deactivated silica gel precolumn and an activated silica gel main column by eluting the saturate and aromatic hydrocarbon fractions from the activated silica column with hexane in the forward and back-flush modes respectively. Polar nonhydrocarbons were backflushed from the precolumn with methylene chloride-methanol. Carbon isotopes were done on a subset of hydrocarbon fractions at Coastal Sciences Labs, Austin, TX (Table 3). 

Pressurized liquid extraction (PEE) has received numerous names, such as accelerated solvent extraction (ASE), pressurized fluid extraction (PEE), pressurized hot-solvent extraction (PHSE), subcritical solvent extraction (SSE) and hot-water (H2O) extraction (HWE). PEE is carried out at temperatures above the boiling point of the solvent and uses high pressure to maintain the solvent in the liquid phase and achieve fast and efficient extraction of analytes from the solid matrix. HWE is being increasingly used in residue analysis, due to low cost, low toxicity, and ease of disposal. At ambient temperature and pressure H2O is a polar solvent, but if the temperature and pressure are increased, the polarity decreases considerably, and H2O can be used to extract medium to low polarity analytes. ... 

The subsequent isolation of flavor volatiles by simultaneous distillation/extraction and the preseparation into 6 fractions by medium pressure liquid chromatography as well as the analytical and preparative conditions (capillary gas chromatography, spectroscopy) were previously published [7,9]. 

The individual washes were successively extracted with dichloromethane (3 x 50 mL) and all the organic layers were combined, washed with saturated sodium chloride solution, and dried over magnesium sulfate. The dried solution was concentrated and passed through a Jlorosil column eluting with 10% diethyl ether in hexane and the solvent was removed from the eluate. The crude product was transferred in a vacuum train at room temperature, and small scale (2-4 g) medium-pressure liquid chromatography on silica gel using 3% diethyl ether in hexane afforded pure product 1795 in 80% yield. 

Particularly extractions of fatty substances are carried out with propane in high pressure liquid/liquid mode. Although this extraction medium may be used in supercritical condition, this limiting case of liquid/liquid extraction was considered for design, because the required vaporization heat is maximized. The extraction is operated at a pressure of merely 80 bar and a temperature of 55°C. The further steps are the first decompression, evaporation and overheating to vapour conditions at 15 bar, 65°C followed by the second precipitation at 10 bar, 65°C. Afterwards the vapour will be liquified through condensation, recompressed and - in this case - reheated to extraction conditions. 

The extract that was collected was a pale yellow liquid. The pressure was then raised to a medium pressure level of 3000 psi and another volume of gas passed through the same charge of shredded ginger. The extract that was collected was yellow-green in color, but a thicker paste than that obtained in the previous test carried out at 5000 psi. 

Sample preparation. For the study of trace compounds we used two different sample preparation procedures SPI and SPII for wine no. 1 and wine no. 2, respectively. The first flavor extract SP I was obtained by liquid-liquid extraction with fluorochloromethane and dichloromethane (9+1) from 45 L Scheurebe wine. For further analysis a portion of 1/3 was used. After separation on silica gel (pentane/diethyl ether) 6 fractions were analyzed. For the second flavor extract SP II we started from 200 L wine stripping off volatile compounds with vapour in a spinning cone column (SCC) system (5). The condensate was sequentially collected in two main portions of 8 and 2 L, respectively. The first condensate was discarded. The second condensate (2 L) was subjected to liquid-liquid extration with fluorochloromethane and dichloromethane (9+1). After separation on silica gel (pentane/diethyl ether) using medium pressure chromatography (MPLC) 4 fractions were analyzed. 

Supercritical fluid extraction Supercritical fluid extraction (SFE) uses compressed gas as the extraction medium and circumvents some of the problems associated with the use of classical separation techniques involving organic solvents. This technique combines features of distillation (i.e., separation because of differences in component volatiles) and liquid extraction (i.e., separation of components that exhibit little difference in their relative volatilities or that are thermally labile). A number of gases, when compressed isothermally at a temperature greater than their critical temperature and to pressures greater than their critical pressure, exhibit an enhanced solvating power (136), which has been known since the nineteenth century (137, 138), but its actual applications did not come to practice until the late twentieth century. 

---