Acid alumina column

This procedure is then repeated again. Distillation of the combined residues using a nitrogen leak (Note 16) yields 54 g. of the product as a yellowoil, b.p. 66-68° (1.1 mm.) (Note 17). The distillation residue, when washed through a short acidic alumina column with light petroleum ether and the solvent evaporated, yields an additional 5 g. of product total yield 59-68 g., 67-78% (Notes 18, 19). 

Relatively simple cleanup steps have been used in some analytical methods for BFRs. For example, in determination of PBDEs in human mUk, the dominating PCB congeners in the LEE extract were removed by passage through a sihca column. A similar method was used for PBDEs, toxaphene, and chlordane compounds in seal blubber extracts. The hquid extracts after treatment with sulphuric acids in hexane were purified twice by silica gel column, and after elution of PCBs with hexane the analytes were eluted with a mixture of hexane and diethyl ether. PBBs and DeBDE have also been eluted from sihca gel with isooctane, and other PBDEs with diethyl ether isooctane, as was done with Soxhlet extracts of various marine mammals after treatment of the extract with sulphuric acid." Alumina columns have been used in a similar manner for Soxhlet extracts of sediment samples in the determination of PBDEs. Concentrated acetone hexane extract was passed through an alumina column and BFRs were eluted with hexane. ... 

Different resins, including acid alumina, silica gel, C-18 reverse phase, and florisil, as well as different solvents, were evaluated for their ability to clean-up the heptachlor-spiked samples for an immunoassay. The data obtained using acid alumina and C-18 reverse phase resin as the solid support and elution with 20 mL of the solvent indicated are siunmarized in Table n. It may be noticed that many of the resin/elution solvent combinations were able to give >9S% recoveries of the heptachlor (based on 1 C-heptachlor recovery), but when non-spiked beef fat samples were analyzed in the cELISA inhibition values of from 18 to 7S% were observed. The inhibition, observed in nonspiked samples represents unknown interfering compounds that coeluted with heptachlor. In the case of chromatography on an acid alumina column followed by elution with 20 mL of 75% acetonitrile in water, only 18% inhibition in nonspiked samples was observed. Material from identical experiments using nonspiked and spiked beef fat were collected as 3 mL fractions. Each fraction was then analyzed... 

Figure 3. Chromatography of heptachlor spiked beef fat on an acid alumina column. Panel A. Percent recovery of l C-heptachlor (hatched bars) and % recovery of fat (% of starting mass) (open bars). Panel B. cELISA results for fractions 1 and 2 from nonspiked beef samples, nd = not done.

Aromatic hydrocarbons can be purified as their picrates using the procedures described for amines. Instead of picric acid, 1,3,5-trinitrobenzene or 2,4,7-trinitrofluorenone can also be used. In all these cases, following recrystallisation, the hydrocarbon can be isolated either as described for amines or by passing a solution of the adduct through an activated alumina column and eluting with toluene or petroleum ether. The picric acid and nitro compounds are more strongly adsorbed on the column. 

Biphenyl [92-52-4] M 154.2, m 70-71 , b 255 , d 0.992. Crystd from EtOH, MeOH, aq MeOH, pet ether (b 40-60 ) or glacial acetic acid. Freed from polar impurities by passage through an alumina column in benzene, followed by evapn. A in CCI4 has been purified by vac distn and by zone refining. Treatment with maleic anhydride removed anthracene-like impurities. Recrystd from EtOH followed by repeated vacuum sublimation and passage through a zone refiner. [Taliani and Breed Phys Chem 88 2351 1984.]... 

Bromoacetic acid [79-08-3] M 138.9, m 50 , b 118 /15mm, 208 /760mm, pK 2.92. Crystd from pet ether (b 40-60°). Diethyl ether soln passed through an alumina column, and the ether evaporated at room temperature under vacuum. LACHRYMATORY. 

Dried with Linde type 5A molecular sieves or Na2S04 and fractionally distd at reduced pressure. Alternatively, it was refluxed with, and distd from, BaO. Also purified by fractional crystn from the melt and distd from zinc dust. Converted to its phosphate (m 135°) or picrate (m 223°), which were purified by crystn and the free base recovered and distd. [Packer, Vaughn and Wong J Am Chem Soc 80 905 1958.] The procedure for purifying via the picrate comprises the addition of quinoline to picric acid dissolved in the minimum volume of 95% EtOH to yield yellow crystals which are washed with EtOH and air dried before recrystn from acetonitrile. The crystals are dissolved in dimethyl sulfoxide (previously dried over 4A molecular sieves) and passed through a basic alumina column, on which picric acid is adsorbed. The free base in the effluent is extracted with n-pentane and distd under vacuum. Traces of solvent are removed by vapour phase chromatography. [Mooman and Anton J Phys Chem 80 2243 1976.]... 

Perfluoro(methylcyclohexane) [355-02-2] M 350.1, b 76.3", d 1.7878. Refluxed for 24h with saturated acid KMn04 (to oxidise and remove hydrocarbons), then neutralised, steam distd, dried with P2O5 and passed slowly through a column of dry silica gel. [Glew and Reeves J Phys Chem 60 615 1956.] Also purified by percolation through a Im neutral activated alumina column, and H-impurities checked by NMR. 

For smaller batches, purification by washing the product through a short column of acidic alumina with light petroleum ether and evaporation of the solvent is satisfactory. 

If the liquids remain discolored even after these precautions, it is often possible to purify them further by first stirring with activated charcoal, followed by passing the liquid down a short column of neutral or acidic alumina as discussed in Section 2.1.3.2 [33]. 

The cobalt complex is usually formed in a hot acetate-acetic acid medium. After the formation of the cobalt colour, hydrochloric acid or nitric acid is added to decompose the complexes of most of the other heavy metals present. Iron, copper, cerium(IV), chromium(III and VI), nickel, vanadyl vanadium, and copper interfere when present in appreciable quantities. Excess of the reagent minimises the interference of iron(II) iron(III) can be removed by diethyl ether extraction from a hydrochloric acid solution. Most of the interferences can be eliminated by treatment with potassium bromate, followed by the addition of an alkali fluoride. Cobalt may also be isolated by dithizone extraction from a basic medium after copper has been removed (if necessary) from acidic solution. An alumina column may also be used to adsorb the cobalt nitroso-R-chelate anion in the presence of perchloric acid, the other elements are eluted with warm 1M nitric acid, and finally the cobalt complex with 1M sulphuric acid, and the absorbance measured at 500 nm. 

A polyethylene-coated (PEE) silica column was used with water-methanol eluents to achieve the separation and retention of 27 pesticides.40 The retention times of 33 commercial pesticides were determined on an octadecyl (ODS)-derivatized alumina column using water-methanol eluents and compared with retention properties on an ODS-silica column packing.41 More recently, RP-HPLC was used in combination with diode array detection for the identification and quantification of 77 pesticides (acidic, basic, and neutral) in groundwater samples.42... 

General Considerations. The following chemicals were commercially available and used as received 3,3,3-Triphenylpropionic acid (Acros), 1.0 M LiAlH4 in tetrahydrofuran (THF) (Aldrich), pyridinium dichromate (Acros), 2,6 di-tert-butylpyridine (Acros), dichlorodimethylsilane (Acros), tetraethyl orthosilicate (Aldrich), 3-aminopropyltrimethoxy silane (Aldrich), hexamethyldisilazane (Aldrich), tetrakis (diethylamino) titanium (Aldrich), trimethyl silyl chloride (Aldrich), terephthaloyl chloride (Acros), anhydrous toluene (Acros), and n-butyllithium in hexanes (Aldrich). Anhydrous ether, anhydrous THF, anhydrous dichloromethane, and anhydrous hexanes were obtained from a packed bed solvent purification system utilizing columns of copper oxide catalyst and alumina (ether, hexanes) or dual alumina columns (tetrahydrofuran, dichloromethane) (9). Tetramethylcyclopentadiene (Aldrich) was distilled over sodium metal prior to use. p-Aminophenyltrimethoxysilane (Gelest) was purified by recrystallization from methanol. Anhydrous methanol (Acros) was... 

Extraction of nalidixic acid with chloroform from utine has also been reported.(40) Another fluorimetric method for chicken liver and muscle containing not less than 100 ppb nalidixic acid was reported by Browning(9) using an ethyl-acetate extraction and alumina column to retain the nalidixic acid. The fluorescence was measured at 325/408 nm. 

A dichloromethane solution of [Run(L 3) (CO) (EtOH)] (0.07 mmol) was added to a well-stirred dichloromethane solution of ra-chloroperoxy benzoic acid (100 mg, 0.62 mmol) in a 10 mL round-bottomed flask. After 3 to 5 minutes stirring, the mixture was poured onto a short dry alumina column. 

In column chromatography, the adsorbant is usually alumina but can be silica gel. Except that alumina tends to be basic and silica gel, acidic, I don t know why the former is used more often. Remember, if you try out an eluent (solvent) on silica gel plates, the results on an alumina column may be different. 

Blackburn et al. [18] collected a series of fish samples taken from marine and freshwater for food quality assurance purposes. The marine fish contained no detectable levels of APEO residues (0.05-0.1 pgg-1 NP). Samples were extracted with DCM in a Soxhlet extractor. Samples were concentrated and further purified on alumina columns using hexane to elute lipids and 1 1 hexane/acetone to collect the analytes. Samples of marine fish were further cleaned up with a second alumina column. APs were collected by combining the elutriates from a first elution with 10% acetic acid in hexane, and a subsequent hexane elution. 

There are two noncolumn cleanup methods, one of which uses acid partition (EPA SW-846 3650) to separate the base/neutral and acid components by adjusting pH. This method is often used before alumina column cleanup to remove acid components. The other method (EPA SW-846 3660) is used for sulfur removal and uses copper, mercury, and tetrabutylammonium sulfite as desulfurization compounds. Sulfur is a common interfering compound for petroleum hydrocarbon analysis, particularly for sediments. Sulfur-containing compounds are very common in crude oil and heavy fuel oil. Elemental sulfur is often present in anaerobically biodegraded fuels. Thus, abnormally high levels of sulfur may be... 

The tert-butyl derivative 343 quantitatively eliminates iso-butene and carbon dioxide on a neutral alumina column. The obtained aziridine can be esterified in good yields with acid chlorides in ODCB in the presence of pyridine [398, 399]. 

In this preparation the nitroso compound may be added in solution form to a solution to the amine at low temperature. The solvent may be a suitable mixture of acetic acid and ethanol as well as acetic acid alone. The product may also be extracted from a reaction mixture diluted with water by use of ether [32]. Purification of the final product may be carried out by chromatography on an alumina column. 

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