New Chromosorb G ...the first support specifically developed for gas chromatography —offers greater column efficiency, less adsorptive surface; is much harder, less fragile and provides maximum uniformity and reliability Chromosorb® G is the first diatomite a g g r e g a t e ex pressly developed and made for use as a column support in gas chromatography. Johns-Manville, recognizing the need for highest performance, is now specially selecting r a w materials, blending and m a n u f a c t u r i n g under strin gent control, and processing the completely new aggre gate to size graded supports. Specifically, Chromosorb G is now available as a column material to provide improved performance over previously used supports in many separations. Chromo sorb G combines, to a substantial degree, the high column efficiency and good handling characteristics of Chromosorb Ρ with the comparatively non-adsorptive surface of Chromosorb W. As a column packing, Chrom osorb G is a relatively dense, h a r d material, oyster-white in color, with a low surface area. Chromosorb G has been designed for use for the sepa ration of polar compounds where surface interaction is frequently a problem. I t is well suited for use at rela tively low liquid loadings. Chromosorb G is available in three t r e a t m e n t s , pack aged in 1 /2-lb. glass bottles and 25-lb. bulk packages. Non-acid-washed ( N A W ) . This is the s t a n d a r d form and is w i t h o u t a d d i t i o n a l t r e a t m e n t ; Acid-washed (AW) ; Acid-washed, dimethyldichorosilane t r e a t m e n t ( A W - D M C S ) . The combination of acid washing and DMCS t r e a t m e n t f u r t h e r reduces surface activity. This is the most inert form of Chromosorb G. Each t r e a t m e n t is available in the following mesh r a n g e s : 30/60,40/50, 45/50, 45/60, 50/60, 60/70, 60/80, 70/80, 80/100, 100/120, 120/140. Chromosorb G is a hard, dense material differing con siderably in s t r u c t u r e and density from Chromosorb Ρ and Chromosorb W. I t is 2.4 times as heavy as W and 1.2 times as heavy as P . The following table compares the physical properties of the three grades :
JOHNS-MANVILLE
Chromosorb G METHANOL
Comparison of adsorption e f f e c t s under c o n d i t i o n s chosen to emphasize tailing. Squalane liquid phase.
Conventional white support METHANOL
C o m p a r i s o n of Physical Properties of C h r o m o s o r b G, C h r o m o s o r b W a n d C h r o m o s o r b Ρ 6 0 / 8 0 M e s h , N o n - a c i d Washed Grades Color
Chromosorb G Oyster white
Chromosorb W White
Chromosorb Ρ Pink
0.47 0.58 0.5 0.29 8.5
0.18 0.24 1.0 0.29 8-10
0.38 0.47 4.0 1.88 6-7
Free fall density, g/cc Packed density, g/cc Surface area, m V g Surface area, m V c c PH
Your regular Chromosorb dealer can furnish you with new Chromosorb G. F o r additional information on handling and performance of Chromosorb G, w r i t e Johns-Manville for Technical Bulletin F F - 1 2 1 .
JM Celite Division
Circle No. 51 on Readers' Service Card
VOL. 36, NO. 9, AUGUST 1964
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55 A
