In order to detect hydrogen gas using the TCD, Argon as carrier gas, can a mega bore capillary column with diameter 530 mm be used instead of a molecular sieve column?
I appreciate any information.
A molecular sieve stationary phase is generally required for separation of permanent gases. This is largely due to the very low level of interaction of these gases with other stationary phases. That being said, there are porous layer open tubular (PLOT) columns that are capillary columns, and have the molecular sieve bonded to the wall of the capillary. I expect that you will likely need a 5A molecular sieve stationary phase as compared to some of the other types of PLOT columns.
Dear Tayebeh Sharifi,
Maybe you will have to lower the temperature of your column. Although I did this kind of separation 30 years ago, I imagine that you may still have to lower the temperature. In that time we immerse the sieve column in a mix of dry ice and ethanol to reach the kind of lower temperature we needed. Is it still necessary today? I don't know but quite low temperatures must be still necessary.
Very good question, but why mega bore capillary column? I would think you would want a capillary column with the thickest film coating and smallest internal diameter to create a similar solid phase interaction condition as a 10M packed molecular sieve column (higher theoretical separation plates.) While thermal partition is the primary separation driving force in GC analysis, one still needs additional partitioning interactions to achieve separation of analytes in your gas samples. A polar film coating will retain water, ammonia, & polar VOC molecules, and a non-polar coating will help partition VOC gas molecules in your sample. Why not butt-connect a 15m DB-Wax & 15m SPB-624, to achieve the best Phase Ratio (β). Do not forget to apply physical chemistry of treating your gas sample as a liquid in behavior, you still are introducing a sample plug onto the column and plug formation and its interaction with the solid phase will give you better peak shape.
Agilent has a paper where they used a micro TCD & 10M MS5A column, for better H2 gas detection and were able to achieve separation at an 80C oven temperature. I hope this reference will help you achieve your goal https://www.agilent.com/cs/library/applications/5991-3199EN.pdf
Ademario Junior Many thanks for your comment, I am not sure such a low temperature is needed anymore, maybe for special cases!!!
https://www.sigmaaldrich.com/US/en/technical-documents/technical-article/analytical-chemistry/gas-chromatography/gc-column-selection-guide
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