Summary
The selection of the average linear carrier gas velocity in the analysis of a multicomponent mixture under isothermal and programmed-temperature conditions is discussed. It is shown that one shouls always select a velocity which is at least equal but preferably higher than the optimum average gas velocity of the earliest peak at the initial column temperature.
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Abbreviations
- a, a′:
-
constants
- b, b′:
-
constants
- Bo :
-
specific column permeability
- df :
-
average thickness of the liquid phase film
- DG :
-
diffusion coefficient of a smaple component in the carrier gas
- HETP:
-
height equivalent to a theoretical plate
- HETPmin :
-
the HETP value corresponding to the minimum of the van Deemter plot
- HETPmin(theor) :
-
the calculated theoretical HETP values corresponding to the minimum of the van Deemter plot
- j:
-
compressibility correction factor (see eq. (12))
- j′:
-
compressibility correction factor (see eq. (15))
- k:
-
capacity ratio, k=t′R/tM
- K:
-
partition (distribution) coefficient
- L:
-
column length
- n:
-
number of theoretical plates
- Pi :
-
carrier gas (absolute) inlet pressure
- Po :
-
carrier gas (absolute) outlet pressure
- Δp:
-
pressure drop along the column (see eq. (14))
- P:
-
relative pressure in the column (see eq. (13))
- rc :
-
inside column radius
- tM :
-
gas holdup time
- tR :
-
retention time (measured from the point of injection)
- t′R :
-
adjusted retention time, t′R=tR-tM
- T:
-
column temperature (°K)
- uo :
-
linear carrier gas velocity at column outlet
- ū:
-
average linear carrier gas velocity
- ūopt :
-
the average linear carrier gas velocity corresponding to the minimum of the van Deemter plot
- ūopt(theor) :
-
the calculated theoretical average linear carrier gas velocity value corresponding to the minimum of the van Deemter plot
- z:
-
the number of carbon atoms in a molecule
- β:
-
phase ratio
- η:
-
vicosity of the carrier gas
References
J. H. Purnell, Nature (London)184, 2009 (1959).
T. P. W. Scott andG. S. F. Hazeldean, in Gas Chromatography 1960 (Edinburgh Symposium),R. P. W. Scott, ed., Butterworths, London, 1960; pp. 144–161.
D. H. Desty andA. Goldup, in Gas Chromatography 1960 (Edinburgh Symposium),R. P. W. Scott, ed., Butterworths, London, 1960; pp. 162–183.
L. S. Ettre, Open Tubular Columns in Gas Chromatography, Plenum Press, New York, 1965.
G. Guiochon, “Flow of Gases in Porous Media. Problems Raised by the Operation of Gas Chromatographic Colums.” In Chromatography Reviews,M. Lederer, ed., Elsevier, Amsterdam, 1966, Vol. 8, pp. 1–47.
British Standard 3282:1969:Glossary of Terms Relating Gas Chromatography, British Standards Institution, London (first published 1963, latest revision 1969).
ASTM E 355-77: Gas Chromatography Terms and Relationships, American Society for Testing & Materials, Philadelphia, Pa. (first published 1968, latest reviesion 1977).
IUPAC, Recommendation on Nomenclature and Presesntation of Data in Gas Chromatography, Pure Appl. Chem.8, 553 (1964).
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These symbols essentially correspond to those specified by the British Standard [6], ASTM [7] and IUPAC [8] GC nomenclastures.
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Ettre, L.S. Selection of carrier gas velocity in the analysis of a multicomponent sample. Chromatographia 12, 509–515 (1979). https://doi.org/10.1007/BF02303003
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DOI: https://doi.org/10.1007/BF02303003