Column packings alumina

This type of analysis requires several chromatographic columns and detectors. Hydrocarbons are measured with the aid of a flame ionization detector FID, while the other gases are analyzed using a katharometer. A large number of combinations of columns is possible considering the commutations between columns and, potentially, backflushing of the carrier gas. As an example, the hydrocarbons can be separated by a column packed with silicone or alumina while O2, N2 and CO will require a molecular sieve column. H2S is a special case because this gas is fixed irreversibly on a number of chromatographic supports. Its separation can be achieved on certain kinds of supports such as Porapak which are styrene-divinylbenzene copolymers. This type of phase is also used to analyze CO2 and water. 

In liquid-solid adsorption chromatography (LSC) the column packing also serves as the stationary phase. In Tswett s original work the stationary phase was finely divided CaCOa, but modern columns employ porous 3-10-)J,m particles of silica or alumina. Since the stationary phase is polar, the mobile phase is usually a nonpolar or moderately polar solvent. Typical mobile phases include hexane, isooctane, and methylene chloride. The usual order of elution, from shorter to longer retention times, is... 

Diisooctyl phenylphosphonate [49637-59-4] M 378.5, n 1.4780. Vacuum distilled, percolated through a column of alumina, then passed through a packed column maintained at 150 to remove residual traces of volatile materials in a countercurrent stream of N2 at reduced pressure [Dobry and Keller J Phys Chem 61 1448 1957]. 

Tetraethylsilane [631-36-7] M 144.3, b 153.8"/760mm, d 0.77, n q 1.427. Fractionate through a 3ft vacuum jacketted column packed with 1/4" stainless steel saddles. The material is finally percolated through a 2ft column packed with alumina and maintained in an inert atmosphere. [7 Chem Soc 1992 1954- J Am Chem Soc 77 272 7955.]... 

Tri-p-tolyl phosphate [20756-92-7, 1330-78-5 (isomeric tritolyl phosphate mixture)] M 368.4, b 232-234 , d 1.16484, n 1.56703. Dried with CaCl2, then distd under vacuum and percolated through a column of alumina. Passage through a packed column at 150°, with a counter-current stream of nitrogen, under reduced pressure, removed residual traces of volatile impurities. 

One important factor to consider in the preparation of the organic phase is the presence of inhibitors in the monomers. Some formulae call for the removal of inhibitors, primarily TCB, from the monomers. The TCB inhibitor forms highly colored complexes with metallic salts rendering the final product colored. Styrene has about 50 ppm of TCB. DVB, being more reactive, contains about 1000 ppm of TCB. There are several options for the removal of inhibitors. Columns packed with DOWEX MSA-1 or DOWEX 11 ion-exchange resins (Dow Chemical Company) can be used. White drierite or activated alumina also works well. 

Dichloromethane (unstabilized HPLC grade) was purchased from Fisher Scientific and was dried by percolation through two columns packed with neutral alumina under a positive pressure of argon. 

Because plants present chlorophylls and carotenoids simultaneously, it may be useful to separate both groups from each other in a laboratory or preparative scale in order to avoid contamination in further purification steps, mainly when they are prepared in large amounts. Clean-up procedures using an open column packed with absorbents such as alumina, magnesia, polyethylene powder, powdered sucrose, DEAE-Sepharose, starch, cellulose, or MgO HyfloSupercel are good approaches. MgO HyfloSupercel in a proportion of 1 1 or 1 2 is the usual adsorbent. Sucrose and cellulose are interesting as they do not alter the chlorophylls, but they are tedious to work with. 

Glass chromatography column, 1.5-cm i.d. x 45 cm with a stopcock Alumina column Place a cotton wool plug at the bottom of a glass chromatography column. Pack 15 g of alumina slurried with n-hexane-ethyl acetate (6 1, v/v) into the glass column. Make an anhydrous sodium sulfate layer of about 1 cm above and below the alumina bed... 

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... 

It is difficult to keep an electrolyte solution completely free from water, even when the experiment is carried out in a glove box or with a vacuum line. In such cases, procedures such as adding powdered active alumina directly into the electrolyte solution or passing the electrolyte solution through a column packed with active alumina can be used to remove residual water [16]. These procedures are also effective in removing various impurities, which are either acidic, basic, nucleophilic or electrophilic. However, it should be noted that some of the electroactive species may also be adsorbed onto the powder. 

Vinyl Ferrocene [Vinyl-dicyclopentadienyl-iron of Cyclopentadienyl-(vinylcyclopentadienyl)-iron]. CH2 CH.CsH4.Fe.CsHs,C 2H 2Fe mw 212.09 red solid with a strong camphor-like odor mp 48—49° bp 80—85° at 0.2mm. V sol in eth, methanol and petr eth. Prepn is by pyrolysis of cyclopentadienyl-(ot-hydroxyethy-cyclopentadienyl)-iron using alumina at 200° under reduced pressure. The process used for the pyrolysis is distln. The crude desired product remains on the distln column s alumina packing. The 21% yield is removed from the packing when... 

Methanol, ethanol, n- and isopropyl alcohol and allyl alcohol were determined by gas chromatography on a 3-meter column packed with 15% Hallcomid on 60-80 mesh acid-washed Chromosorb. Methane, ethane, ethylene, and propylene were also determined by gas chromatography using a 3-meter column packed with 60-80 mesh activated alumina. Products were identified by comparing their retention times with those of pure standards. 

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