Tubing column

The length of the column is also defined by the Poiseuille equation that describes the flow of a fluid through an open tube in terms of the tube radius, the pressure applied across the tube (column), the viscosity of the fluid and the linear velocity of the fluid. Thus, for a compressible fluid. 

Four column systems are available from Amersham Pharmacia Biotech that can be used to pack SEC media for various applications at the laboratory scale. These include C, XK, SR, and HR column systems. All of the laboratory-scale columns are constructed with borosilicate glass tubes. Columns for larger scale process applications include INdEX, BPG, EineLINE, BPSS, and Stack columns. The larger scale columns are constructed to meet stringent validation requirements for the production of biopharmaceuticals. Each of the column types are described. 

Thin-layer chromatography (TLC) is a type of liquid chromatography in which the stationary pease is in the form of a thin layer on a flat surface rather than packed into a tube (column). It is a member of a family cf techniques that include some types of electrophoresis and paper chromatography, more generally referred to as planar chromatccraphy. Since we will not discuss electrophoresis in this section, and since TLC has virtually superseded paper chromategr pby in most analytical... 

For example for the preparation of a 15 cm long, 4.6 mm i.d. stainless tube column, 2.5 g of octadecyl-bonded silica gel was suspended in 25 ml of hexanol-methanol mixture, and kept in an ultrasonic bath for a few minutes to remove air. After the reservoir was filled with the slurry, methanol was pumped in at 10 ml min -1 under constant pressure, 45 MPa (450 bar). After the replacement of slurry solvent by methanol, the flow was stopped and the pressure allowed to drop. When 0 MPa was reached the reservoir was removed. Then, 20 ml of water was added and methanol was again pumped in under the same conditions as before. Again, the flow was stopped and the pressure allowed to drop until it reached 0 MPa. The pre-column was removed and the analytical column closed. The maximum pressure that can be applied in the filling stage is based on the pore size, particle shape, and purity of the silica gel. This reproducible packing procedure is performed at constant temperature by using a water bath (60-BO °C). 

Where (VO is the volume of stationary phase m the open tube column, (Vm) is the volume of mobile phase in the open tune column,... 

To a distillation flask is added 29.0 gm (0.244 mole) of 3-bromopropyne and 2.5 gm (0.0174 mole) of dry cuprous bromide. The flask is attached to a concentric-tube column (25-30 theoretical plates), and the temperature of the flask is controlled so that the takeoff temperature at the head remains at 72.8°-73.5°C. In 24 hr, 24.4 gm (84 %) of bromopropadiene of 75-85 % purity is obtained. The remaining 3-bromopropyne (propargyl bromide) is removed by washing the product with a 40 % aqueous solution of diethylamine. Three to four moles of diethylamine is used for each mole of propargyl bromide in the product as calculated from VPC or refractive index data. After swirling the mixture (acidified with 15 % hydrochloric acid) for hr, the organic layer is separated, washed with water, dried over potassium carbonate, and distilled quickly under reduced pressure into a Dry Ice-cooled receiver to afford pure bromopropadiene, b.p. 72.8°C (9760 mm), w ° 1.5212, 1.5508. 

Glass U-tube columns are usually filled by gravity without the need for vacuum. It is best to add packing to both arms simultaneously, or in small segments to each arm. Silane-treated glass wool should be used sparingly and is not really needed or recommended in the inlet side. 

Large-volume ovens (1000-3500 cubic inches) for U-tube columns, especially popular in biomedical GC in the past, and for preparative applications. 

The isomeric oxiranes prepared by ring closure of l-bromo-l-phenyl-2-propan-ol (ref. 9) were separated on a Fischer concentric tube column (theoretical plate number 90) (b.p. cis (1) 355 K/13 mm Hg, trans (2) 361 K/13 mm Hg, ac-... 

A flow study of the reaction between oxygen atoms and chlorine at high pressures (Bradley et al, J Chem Soc Trans Faraday Soc 1 1251, 1973) produced data of oxygen concentration along the tube, columns 1 and 2 of the table. The... 

The column length varies from 3 to 30 cm, the inner diameter from 1 to 10 mm. Columns are made of very resistant materials to withstand high pressures (<40 MPa) Most commonly, a stainless steel or heavy-walled glass tube is inserted into a metal tube. Columns are packed with a solid material of particle size <10 pm (spherical and nonporous microglass beads or polymer particles). A guard column is usually placed before the column to remove suspended particles from solvents, as well as certain sample constituents that could irreversibly bind to the stationary phase. 

The optical activities of the chiral oligopropylenes were determined at various wavelengths. Polarimetric measurements were only made for product mixtures from oligomerizations performed with various monomer concentrations and at various reaction temperatures and also for individual fractions of dimers, trimers, and tetramers. The product mixtures were fractionated by distillation over a split tube column (Table XIII). 

The stationary phase can be a liquid or a solid. If it is a liquid, it can be coated directly on the inside walls of a capillary tube (column), or it can be coated on an inert solid support and be handled like a solid. In effect, then, there are three stationary phase configurations in the first type, a solid (with or without stationary liquid) is packed into a column in the second type, a solid is coated on the surface of a flat, plane material like glass (TLC), and in the third type, a liquid is coated on the inside wall of an open tube (OT). 

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