Glass capillary columns characteristics

Alexander, G., and Rutten, G.A.F.M., Surface characteristics of treated glasses for the preparation of glass capillary columns in gas-liquid chromatography, /. Chromatogr., 99, 81-101, 1974. 

The presence of residual THF in the final product is easily detected by the characteristic NMR signals at 6 1.85 (4 H) and 3.75 (4 H). The checkers found GLC to be more convenient than 1H NMR for analysis at this point. Either a 6 x 2 mm glass column of 3% 0V-101 on MHP 80/100 with 30 nt/min He or a 15 m x 0.25 mm fused silica capillary column of DB-5 (cross-linked phenyl silicone) with 1 mL/min H2 proved sufficient to resolve butane, trimethylsilylacetylene, butyltrimethylsilane, THF, 1-chlorobutane, and b1s trimethylsilyl)acetylene. 

Although the experimental conditions for diffusion-controlled current may be in effect for a polarographic measurement, the resultant current may not be controlled purely by diffusional processes. A convenient way to test whether this is true is to vary the height of the mercury column. The fluid flow characteristics of a capillary with a hydrostatic head are such that the diffusion current is directly proportional to the square root of the height of the column (small corrections for the surface tension of mercury on glass and for the hydrostatic backpressure of the water-immersed portion of the capillary are necessary for the most precise measurements)... 

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