Chromatography, column, for

Before releasing a process column for chromatography, it is advisable to perform some test to measure efficiency, such as calculating height equivalent theoretical plates (HETP), both to forestall any problems in the column bed and to provide a benchmark by which to measure column reproducibility and predict degradation of the bed or material. Examples of compounds that are relatively innocuous for use in pharmaceutical applications are 1% NaCl (for gel filtration), concentrated buffer solutions (for ion exchange), and benzyl alcohol and parabens for reverse phase LC.10... 

SFE-SFC operation consists of extraction, trapping, and transfer to the column for chromatography. Concentration of the solutes of interest before sample introduction to SFC may be achieved by ... 

Subsequently, to the extraction product a 5% aqueous sodium hydroxide solution is added while stirring. At a pH of 5.50 the addition of sodium hydroxide is interrupted. The water phase is separated and discarded. The addition of base is then continued until the mixture reaches a pH of 6.0-6.3. The aqueous solution which contains mainly tppts, minor amounts of tppds, and their oxides is separated. By concentration of the aqueous solution until the beginning of crystallization, followed by filtration, washing with methanol, and drying, the sodium salt of the 3,3, 3"-phosphinetriylbenzenesulfonic acid can be obtained as a white solid with a purity of at least 95%. For highest purities the solid is dissolved in water and transferred to a Sephadex G-15 column for chromatography. 

Glass tubes—Approximately 1 in. in diameter and 2 ft in length, or equivalent columns for chromatography. The group will require 50 of these tubes. 

Prepare a column for chromatography with silica gel slurried in dichloromethane, so that the column height is c. 30 cm. Load the solution... 

Prepare a column for chromatography using neutral alumina (activity II—III,... 

Calcein Efflux Assay 1. Efflux buffer (see Subheading 2.4.1., item 3). 2. [2-(Trimethylammonium)ethyl] methanethiosulfonate bromide (MTSET Anatrace, cat. no. TllOMT) 160 mM in efflux buffer (see Note 3). 3. Sephadex G50. 4. Column for chromatography (1.5 cm i.d.xSO cm length). 

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