Summary
The role of the volume of the sample and the sample vial in equilibrium headspace-gas chromatography is discussed. A new term, thesample phase fraction (ΦS) is introduced. It is shown that if the value of ΦS is kept constant, the vial's volume has no influence on the “sensitivity” of the headspace analysis (which is proportional to the concentration of the analyte in the headspace). In a given headspace sampling system, concentration of the compound of interest in the headspace (c *G ) at equilibrium is related to the value of ΦS: a higher ΦS will increase c *G . However, the influence is important only in the case of low distribution coefficients: in the case of higher distribution coefficients this influence is negligible. This conclusion is also true for small changes in the sample volume in duplicate analyses: exact reproducibility of the sample volume is important only in the case of low distribution coefficient values.
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Abbreviations
- a:
-
A term expressed in Eq. (21)
- A:
-
Peak area
- c *G :
-
Concentration of the analyte in the headspace volume of the vial (the gas phase), at equilibrium
- cS :
-
Concentration of the analyte in the original sample
- cS :
-
Concentration of the analyte in the sample placed in the vial, at equilibrium
- GC:
-
Gas chromatography
- HS:
-
Headspace; headspace sampling
- HSGC:
-
Headspace gas chromatography
- K:
-
Distribution (partition) coefficient of the compound of interest at equilibrium, at the thermostating temperature (=c *S /c *G )
- m *G :
-
Amount of the analyte in the headspace volume of the vial (the gas phase), at equilibrium
- mS :
-
Amount of the analyte in the sample placed in the vial, under the original conditions.
- m *S :
-
Amount of the analyte in the sample placed in the vial, at equilibrium
- pi :
-
Carrier gas pressure at column inlet (headpressure)
- po :
-
Atmospheric pressure
- ph :
-
Pressure in the headspace of the sample vial, at equilibrium
- To :
-
Atmospheric temperature
- TV :
-
Temperature in the vial (thermostating temperature)
- VG :
-
Volume of the headspace (the gas phase) in the vial
- VS :
-
Volume of sample in the vial
- VV :
-
Total volume of the vial
- β:
-
Phase ratio of the vial (=VG/VS)
- ΦS :
-
Gas phase (headspace) fraction in the vial (=VG/VV)
- ΦS :
-
Sample phase fraction in the vial (=VS/VV)
- *:
-
Asterisk refers to equilibrium conditions
References
H. Hachenberg, A. P. Schmidt, Gas Chromatographic Headspace Analysis. Heyden & Son Ltd., London, 1977.
B. Kolb (Ed.). Applied Headspace Gas Chromatography, Heyden & Son Ltd., London, 1980.
B.V. Ioffe, A.G. Vitenberg, Head-Space Analysis and Related Methods in Gas Chromatography. John Wiley & Sons, New York, NY, 1984.
B. Kolb, Headspace-Gaschromatographie mit Kapillar-Trennsäulen. Vogel Verlag, Würzburg, 1986.
B. Kolb, P. Pospisil, T. Borath, M. Auer, J. High Resolut. Chromatogr./Chromatogr. Commun.2, 283–287 (1979).
L.S. Ettre, J.E. Purcell, J. Widomski, B. Kolb, P. Pospisil, J. Chromatogr. Sci.18, 116–124 (1980).
W. Closta, H. Klemm, P. Pospisil, R. Riegger, G. Siess, B. Kolb, Chromatogr. Newslett.1, 13–17 (1983).
L.S. Ettre, B. Kolb, S.G. Hurt, Amer. Lab.15 (10), 76–83 (1983).
B. Kolb, D. Boege, L.S. Ettre, Amer. Lab.20 (2), 33–44 (1988).
B. Kolb, Chromatographia15, 587–594 (1982).
L.S. Ettre, E. Jones, B.S. Todd, Chromatogr. Newslett.12, 1–3 (1984).
B. Kolb, P. Pospisil, M. Auer, Chromatographia19, 113–122 (1984).
B. Kolb, unpublished data.
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Ettre, L.S., Kolb, B. Headspace-gas chromatography: The influence of sample volume on analytical results. Chromatographia 32, 5–12 (1991). https://doi.org/10.1007/BF02262458
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DOI: https://doi.org/10.1007/BF02262458