Glass coiled column

Figure 3 Phase distribution diagrams for nine voiatiie two-phase soivent systems obtained from glass coils with various dimensions, as indicated on the ieft. The soiid curve indicates the data obtained from nontreated giass coils and the dotted curve, from silicone-treated glass coils. The thin verticai iine in each diagram indicates the rpm vaiue at which the centrifugal force field created by the rotation equais unit gravity. Note that most soivent systems exhibit the critical rpm value where one phase occupies 100% of the column space on the head side of the coil.

Capillary columns are fabricated from thin-walled stainless steel, glass, or high-purity fused silica tubing (the last is preferred for its inertness). Typical dimensions of the columns, which are coiled, are 25-200 m long and 0.2-0.5 mm i.d. 

Fig. 2.4p shows three types of post-column reactor. In the open tubular reactor, after the solutes have been separated on the column, reagent is pumped into the column effluent via a suitable mixing tee. The reactor, which may be a coil of stainless steel or ptfe tube, provides the desired holdup time for the reaction. Finally, the combined streams are passed through the detector. This type of reactor is commonly used in cases where the derivatisation reaction is fairly fast. For slower reactions, segmented stream tubular reactors can be used. With this type, gas bubbles are introduced into the stream at fixed time intervals. The object of this is to reduce axial diffusion of solute zones, and thus to reduce extra-column dispersion. For intermediate reactions, packed bed reactors have been used, in which the reactor may be a column packed with small glass beads. 

The column is the heart of the gas chromatograph in which the separation process occurs. It consists of a coil of stainless steel, glass or fused silica (quartz) tubing which may be 1 m to 100 m long and have an internal diameter of between 0.1 mm and about 3 mm. 

The biological samples are analyzed with an LKB 900 GC mass spectrometer containing a 4-foot coiled glass column packed with 1% UC-W98 on Gas Chrom Q. The column is maintained at 240°C and the... 

It is also known as the chromatographic column . In reality the heart of a GC is the column duly packed or capillary in which the separation of constituents is materialized. The packed-column is usually a tubing having an internal diameter of 4.0 mm and made up of stainless-steel, copper, cupronickel or glass either bent in U-shape or coiled. Its length varies from 120 cm to 150 M. 

Carrier-gas is transferred from the column through a heated metal capillary, which minimizes the dead volume at the end of the column and prevents condensation of the column effluent prior to its entry into the scrubbing unit. The tube carrying the liquid stream is joined to the gas stream tube, at a T-junction that is joined to the mixing coil by a glass-to-metal seal. Furfural is transferred from the gas stream into the liquid stream and the colour develops the two phases are then separated by the debubbling unit and the liquid stream is re-sampled through the flow cell of the colorimeter. A Technicon peristaltic... 

The microreactor system consists of a pumping module (R2+) and a four-channel heated component (R4). Two independently conducted flow streams are mixed in a T-piece and driven through a convection-flow coil (CFC, volume 10 ml) made of poly(fluoroacetate) (PFA). After the CFC, the flow is guided through Omnifit glass columns [41] packed with immobilized scavengers. 

Gas chromatography was originally a technique for nonpolar analytes, and for such analytes nonpolar packed columns prevailed. Packed columns are typically a glass or stainless steel coil, 1-5 m total length and 2-5 mm internal diameter, which is filled with the stationary phase, or a packing coated with the stationary phase. Early packed columns had low plate numbers and in the majority of instances separation could not be obtained on the basis of the differences in volatility alone. The solution was selective stationary phases, and in the 1960s there were more than 200 different stationary phases available (41). 

Glass columns are available for most ovens. The small to medium ovens usually take 6-to 9-inch coils, whereas the large ovens can take the long U-tubes. U-tubes are easier to pack and do give smaller plate heights when small particles are used. 

A modern gas chromatography capillary column is a small diameter tube made of fused silica glass with the walls coated with a film of a stationary phase. These flexible columns with the lengths ranging from 15 to 105 m and the internal diameters of 0.1-0.75 mm are rolled into coils for mounting into the oven of a gas chromatograph. 

---