Acidification extractions

Cool the flask in ice, acidify with 10 ml. of cold 1 1-hydro-chloric acid and distil under reduced pressure (water pump) until most of the alcohol is removed. Add water to the residue, extract several times with ether, wash the combined ethereal extracts with N ammonia solution until a test portion gives no precipitate upon acidification. Extract the combined alkahne solutions once with a fresh portion of ether, and add the aqueous solution to an excess of dilute hydrochloric acid the final mixture should still be acidic to Congo red. Collect the crystalhne half-ester by filtration at the pump, wash it with water and dry at 100°. The yield is 14-5 g., m.p. 122-125°. Recrystallise by dissolving in about 40 ml. of warm benzene and adding an equal volume of petroleum ether (b.p. 40- 60°) 13 -5 g. of the colourless half-ester, m.p. 125-126°, are obtained. 

The tartaric acid ligand can be recovered (1.52 g, 97%) from the aqueous phase by an acidification-extraction (4 N HCI-ethyi acetate) sequence. The material is essentially pure for future use. 

Having the glucoside, we could now determine its concentration in the leaves. Extract samples of varying sizes were subjected to calcium hydroxide treatment, acidification, extraction, and glc quantitation. The amounts of parasorbic acid obtained from the samples are shown in Figure 1 to be proportional to sample size. 

Apple IS glycosides Extraction with acetone, centrifugation, acidification, extraction with EtAc C-18 acn-h2o- acetic acid HPLC/DAD/MSn/ APCI(-) 100... 

Human urine D, G, equol, ODMA Acidification, extraction with C18 SPE, anion exchangers (DEAE and QAE), enzymatic hydrolysis, silylation BP-1 (deuterated isoflavones) He GC/MS/EI 2... 

Beef liver (or lung) was minced and then autolyzed for twenty-four hours before extraction with an alkaline solution saturated with ammonium sulfate. Protein was precipitated by warming the extract, and the heparin-protein complex was precipitated from the supernatant liquor on acidification. Extraction of the complex with ethanol removed fatty material, and tryptic digestion removed most of the protein. The heparin was precipitated with ethanol, redissolved in warm alkaline solution to destroy trypsin, and reprecipitated with acetone. This material, crude heparin, was isolated in a yield of 15-50 g. per 100 lb. of animal tissue. In a later paper," the purification of crude heparin by fractionation successively with Lloyd s reagent, cadmium chloride, and acetone, was described. The purified heparin w-as 100 times as active as the crude material. Scott and Charles" reported the presence of nitrogen... 

The imidazole on the histidine side chain may be protected as a 2-nitrobenzyl derivative which leads to a nnixture of N"- and N -derivatives. Generally, the x-derivative dominates, and can often be isolated pure by recrystaUization. The group is installed by reaction of the silver salt of Boc-His-OMe (13) with 2-nitrobenzyl bromide in refluxing benzene (Scheme 20).b l The product 14 was immediately saponified and, after acidification, extracted into ethyl acetate to give the acid in yield 60-70%. Photolysis of this material was affected by irradiating a 0.001 M solution in dioxane for 1 hour with Pyrex-filtered UV light from a mercury vapor lamp to give Boc-His-OH in quantitative yield. 

GC analysis. However, Kanno et al. (1985) determined MeHg in environmental samples as dithizone complexes by GC-ECD. The samples were treated with an ethanol solution of potassium hydroxide and, after acidification, extracted with benzene-dithizone. The mercury complex was extracted into aqueous ethanoi containing sodium suifide. After acidification, the excess of sulfide was removed by air bubbling, MeHg was again extracted into benzene-dithizone, and analyzed by GC. The detection limit was 0.5 [Pg.443]

ZnO in 4.7 x 10 M aqueous thiobenoarb, photoreactor, provided a mixture of photoproducts, acidification, extraction with a bonded-phase cartridge, and elution, eluates were dried over anhyd sodium sulfate and concentrated under The c-8 cartridge eluate (meth mol) was... 

The hop beta acids are isolated by dissolving a hop extract in hexane ( 20%) and extracting this solution first with disodium carbonate 0.3 N and then with sodium hydroxide 1 N. The alpha acids are found in the disodium carbonate solution, while the less acidic beta acids are extracted only with the stronger base. After acidification, extraction with iso-octane and removal of the solvent, a crystalline residue is obtained, which contains the crude mixture of the beta acids (1). 

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