Title of article :
Service life of counter-current chromatography coils
Author/Authors :
Conway، نويسنده , , Walter D.، نويسنده ,
Issue Information :
روزنامه با شماره پیاپی سال 2007
Pages :
5
From page :
103
To page :
107
Abstract :
A multilayer coil of PTFE tubing, which failed after being used each workday for about 3 years in a type J centrifuge, was examined. Two types of defects were found. One, called crazes, occurs throughout the coil and does not leak initially, but may eventually lead to a short, axially oriented slit. Another, called indentations, is seen primarily in the innermost and other nearby layers. They are elongated, about 5 mm, indentations, usually on the central side of the tubing. These eventually crack and leak. PTFE tubing is permeable to air and hexane and expands by more than 1% when immersed in hexane, heptane or chloroform for a few days. It is suggested that the crazes result from exposure of the somewhat flexible tubing to the undulating centripetal force field in the coil-planet centrifuge, especially when further softened by solvent absorption. The indentations may result from carriage of the excess tubing length, created by solvent absorption, from the coil periphery to the coil center by the centripetal force field, which continuously travels from the peripheral tail to the central head of the coil. A 1% increase in coil length creates 74 cm of excess tubing in the 160-ml coils examined in this study. It is suggested that fluorinated ethylene propylene (FEP) tubing, especially when etched on the outside, may provide more stable CCC coils, since its expansion when exposed to organic solvents is 0.1 or less than that of PTFE.
Keywords :
Counter-current chromatography , CCC , PTFE tubing , CCC coil , PTFE porosity , CCC column , PTFE expansion , FEP tubing
Journal title :
Journal of Chromatography A
Serial Year :
2007
Journal title :
Journal of Chromatography A
Record number :
1521655
Link To Document :
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