Column packings Wire

The submitters used a 7 X 300-mm. externally heated column packed with a helix of Chromel wire and fitted with a partial reflux head.3... 

The distillation is expediently carried out in a set-up which consists of a 500-ml., round-bottomed flask, an electrically heated 1.5 x 30 cm. column packed with V4A wire spirals (4 mm.) (Note 14), a short, aircooled condenser (Note 15), and an ice-cooled, three-necked, 250-ml. 

An early CO distillation pilot plant described by Johns (in London (1961), reading list), used a two section vacuum insulated column packed with wire gauze rings. The upper section was 5.2 m long with a diameter of 3.2cm, the lower 4.6 m x 1.9 cm. The column contained about 600 plates. An intermediate boiler re-evaporated part of the downward flowing liquid at the junction. This plant accumulates product in the liquid and enriches toward the bottom. Enriched CO (0.4 g day-1 of 65% 13C and 0.05 g day-1 of 5% lsO) was withdrawn from the bottom... 

An 8-mm x 1-m jacketed column packed with a coiled tantalum wire was used by the submitters. The checkers used a Vigreux column of similar size. 

Robinson [48] described a gas chromatographic method for measuring residual water in freeze-dried smallpox vaccine in 1972. The method was developed to optimize quality control of a tissue-culture smallpox vaccine. Water is extracted from the sample with benzene and determined by gas chromatography with thermal conductivity (hot wire) detection and columns packed with Chromosorb 102. 

The submitter used an insulated column with a 38 by 1.1 cm. section packed with H-in. copper helices made of No. 26 B S gauge copper wire. He states that a column packed with glass helices is unsatisfactory. The checkers used a 100 by 1.7 cm. Vigreux column. Either type of column shorfld be equipped with a total condensation, partial take-off head. 

The micropyrolytic gas chromatography technique was applied to the identification of siloxane polymers and as an aid to the control of the reproducibility of cross-linked siloxane resins452. In the case of linear polymers the column packing was Apiezon M and a devolatilized linear siloxane polymer (the Hungarian product Hu-Au-120, mol. wt. 59000) supported on Celite. With a detector voltage of 1000 V, column temperature of 100 °C and argon flow rate 20 ml/min, the sample was applied in a solvent-free state to the heated wire-coil. Cross-linked siloxane polymers were analysed as solutions in butyl acetate on a solid support containing 10% linear siloxane polymer as stationary phase under similar conditions. 

In chap. 4.2 it was alreadj pointed out in how far the chemical nature of the material of which the column packing is made may influence the separation. The materials in question are glass, porcelain, earthenware, various metals and their alloys and recently also plastics. Glass or a ceramic material is in general preferred on account of its resistance to corrosion and low price. Porcelain should be hard-baked and free from iron, as catalytic effects may otherwise occur. For high efficiencies packing made of 18 8 stainless steel wire or wire gauze is unsurpassed. 

---