High packed columns

Sample capacity Low High (packed column) High... 

The technology is based on the rapid equhibrium estabUshed between the reactants and products at high temperatures. The equhibrium shifts to the product side when potassium is removed continuously by distihation through a packed column. This process can produce high purity potassium metal. Appropriate adjustments of conditions give a wide range of potassium—sodium ahoys of specified compositions. 

The continuous production of high purity methyl or ethyl carbonate from the alcohol and chloroformates has been patented (80). Chloroformate and alcohol are fed continuously into a Raschig ting-packed column in which a temperature gradient of 72—127°C is maintained between base and head of the column HCl is withdrawn at the head, and carbonate (99%) is withdrawn at the base. 

The assay of ethyleneamines is usually done by gas chromatography. Compared to packed columns, in which severe tailing is often encountered due to the high polarity of the ethyleneamines, capillary columns provide better component separation and quantification. Typically, amines can be analyzed using fused siUca capillary columns with dimethyl silicones, substituted dimethyl silicones or PEG Compound 20 M as the stationary phase (150). 

High recovery of a volatile component by a batch operation is required. Liquid holdup is much lower in a packed column. 

High bcpiid rates can often be bandied more economical ) in plate columns than in packed columns. 

Chloroacetonitrile [107-14-2] M 75.5, b 125 . Refluxed with P2O5 for one day, then distd through a helices-packed column. Also purified by gas chromatography. LACHRYMATOR, HIGHLY TOXIC. 

Next, to determine packed column height use Table 9 for distillation HETP values, leaning tow ards the high side of the range for studies. For use of Kqa values see Section A—Absorbers. Bed height per packed bed runs up to 20-30 ft for metal or ceramic packings, but plastic packing is usually limited to 24 ft. 

The idea of the effective plate number was introduced and employed by Purnell [4], Desty [5] and others in the late 1950s. Its conception was evoked as a direct result of the introduction of the capillary column or open tubular column. Even in 1960, the open tubular column could be constructed to produce efficiencies of up to a million theoretical plates [6]. However, it became immediately apparent that these high efficiencies were only obtained for solutes eluted at very low (k ) values and, consequently, very close to the column dead volume. More importantly, on the basis of the performance realized from packed columns, the high efficiencies did not... 

The packed columns of Shodex OHpak SB-800HQ series are packed with polyhydroxymethacrylate gels and are designed for use with high-resolution, high-speed aqueous size exclusion chromatography. The packed columns are best suited for the analysis of water-soluble polymers and proteins (Table 6.8). 

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