Chromatography, column packing

Reversed-phase silica gel column Place a cotton wool plug at the bottom of a glass chromatography column. Pack 5 g of reversed-phase silica gel slurried with a solvent mixture of n-hexane-benzene-methanol (80 20 0.4, v/v/v) into the glass column. Place an anhydrous sodium sulfate layer about 1 -cm thick above and below the silica gel bed Bell jar-type filtering apparatus Buchner funnel, 11-cm i.d. 

The product may be analyzed by use of a gas chromatography column packed with either LAC-728 (diethylene glycol succinate) or Carbowax 20M suspended on Chromosorb P. Using a 2.5-m. LAC-728 column heated to 100°, the submitters found retention times of 9.4 and 13.0 minutes for cyclohexyl methyl ketone and cyclohexyldimethylcarbinol. Less than 1% of the carbinol by-product was present. 

The various fractions of the forerun were analyzed employing a gas chromatography column packed with silicone gum, No. XE-60, suspended on Chromosorb P and heated to 248°. The components found (with the retention times indicated) were benzyl bromide (9.0 minutes), 2-methylcyclohexanone (5.3 minutes), and, in some cases, bibenzyl (22.6 minutes). The bibenzyl, formed by reaction of the benzyl bromide with the excess methyllithium, was identified from the infrared spectrum of a sample collected from the gas chromatograph. 

The progress of this reaction may be followed by quenching aliquots of the reaction solution in acidic aqueous ammonium sulfate followed by extraction with ether and analysis of the ethereal extract by gas chromatography. With 1.2-m. gas chromatography column packed with silicone fluid. No. 710, on Chromosorb P and heated to 215°, the retention times of naphthalene and 1-bromonaphthalene were 1.9 minutes and 6.7 minutes, respectively. The submitters employed a 30-cm. gas chromatography column packed with Porpak P for this analysis. 

On a 2-m- gas chromatography column packed with 10% Apiezon L and heated to 100°, the retention times for N,N-dimethylcyclohexylamine and cyclohexanol are 15 and 4 minutes, respectively. The composition of this forerun is 80-85% of the amine and 20-15% of the alcohol. 

On a gas chromatography column, packed with Apiezon M suspended on Chromosorb P and heated to 70°, the product exhibits a single peak with a retention time of 23.2 minutes. The sample exhibits infrared absorption (CCI4 solution) at 3100, 3030, 2985, 1440, 1340, and 1235 cm. with n.m.r. singlets (CCI4 solution) at 3.45 (CHaBr) and 0.90 p.p.m. (cyclopropyl CHj). The mass spectrum of the sample has abundant fragment peaks at m/e 149, 147, 67, 41, and 39. 

The product was analyzed with a 2-m. gas chromatography column packed with Carbowax 20M suspended on... 

Table 5. Passage of aqueous Amoxicillin samples over a 3.0 (id) chromatography column packed with 130 ml of Octolig at a flow rate of 10 mL/min (50-mL aliquots were collected and concentrations of fractions 4-10 were measured spectrophotometrically) [44]...

To separate the components of this reaction mixture, the crude product is dissolved in a minimum quantity of petroleum ether. The solution is then passed through a 2 x 20 cm chromatography column packed with aluminum oxide. The nitro and azo compounds are eluted from the column first with sufficient petroleum ether. The azoxy compound is eluted with petroleum ether containing 1 % of methanol. The eluting solvent is evaporated and the residual product is recrystallized from ethanol, m.p. 117°-118°C, nematic-liquid transition point 134°C. 

Chromatography column packed with stationary phase particles... 

In a gel chromatography column packed with particles of average radius 22 pm at an interstitial velocity of 1.2 cm min- of the mobile phase, two peaks show poor separation characteristics, that is, =0.85. 

The product may be analyzed by using a gas chromatography column packed with 20% SF-96 suspended on Chromo-sorb WAW, 5 ft. by 0.25 in., operated at 140°. Using a helium flow rate of 60 ml. per minute the submitters found a retention time of 3.5 minutes. 

Benzene was passed at various temperatures through a gas chromatography column packed with silica gel and the following specific retention volumes (extrapolated to zero sample size) were measured ... 

Williams, R.C., Vasta-Russell, J.F., Glajch, J.L., and Golebiowski, K., Separation of proteins on a polymeric fluorocarbon high-performance liquid chromatography column packing, J. Chromatogr., 371, 63, 1986. 

Ha et al. [93,94] prepared monodisperse polymer microspheres from 1 to 40 pm in diameter for medical diagnostic tests, as chromatography column packing and as calibration standards. The work deals with the synthesis of large and uniform poly (butadiene-styrene) latex. The ceramic SPG membrane, with a pore diameter of 1.6 pm, was employed. The uniform particle sizes were in the diameter range of 4-6 pm. 

A gas chromatography column packed with Apiezon L suspended on Chromosorb P was employed for this analysis. In a typical analysis at 140° the retention times were A1,9-octalin, 46.2 minutes A910-octalin, 49.2 minutes. The n.m.r. spectrum (CC14 solution at 60 mHz.) of this mixture exhibits a multiplet at S 0.8-2.6 (aliphatic CH) with a weak, partially resolved multiplet at <5 5.25 (vinyl CH of A1,9-octalin). 

Melo, L.F.C. Collins, C.H. Collins, K.E. Jardin, I.C.S.F. Stability of high performance liquid chromatography columns packed with poly(methyloctylsiloxane) sorbed and radiation-immobilized onto porous silica and zirconized silica. J. Chromatogr., A 2000, 869, 129-135. 

JJ Kirkland, JL Galjch, RD Farlee. Synthesis and characterization of highly stable bonded phases for high-performance liquid chromatography column packings. Anal Chem 61 2—11, 1988. 

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