Summary
Two different methods were used to determine the separation factor α at different temperatures and the Gibbs-Helmholtz parameters (Δ(ΔH), Δ(ΔS)) of two adjacent benzodiazepines on a chromatogram were obtained from plots of lnα versus 1/T. We first studied each factor (fraction of water ϕ in the ACN/water mixture and column temperatureT), which controls the retention mechanism, and then we examined the simultaneous variation of all these factors. The changes in Δ(ΔH) and Δ(ΔS) in relation to a volume fraction of water ϕ in an ACN/water mixture were examined. In the ACN/water system, Δ(ΔH) was fairly constant in the acetonitrile region of ϕ≤0.52 and appears to be a roughly linear function of ϕ for ϕ≥0.52. In this system Δ(ΔS) is approximately a parabolic function of ϕ with an optimum at ϕ≊0.52. The retention mechanism of ten benzodiazepines was found to be significantly different in the methanol/water and ACN/water mixtures. The separation optimization of these ten benzodiazepines was then considered. A fraction of water of 0.43 in the ACN/water mixture and a column temperature of 44 °C gave the most efficient separation conditions in the ACN/water mixture.
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References
Y. Guillaume, C. Guinchard, Chromatographia40, 193 (1995).
G. E. P. Box, D. W. Benhken, Technometrics2, 455 (1960).
G. E. P. Box, K. B. Wilson, J. Royal. Stat. Soc. B.13, 1 (1951).
G. E. P. Box, W. G. Hunter, S. J. Hunter, Statistics for Experiments, Wiley, part. III, 291, ch. 9–13, New York (1978).
Y. Guillaume, C. Guinchard, J. Liq. Chromatogr.17, 2809 (1994).
Y. Guillaume, C. Guinchard, J. Liq. Chromatogr.16, 3457 (1993).
A. M. Stalcup, D. E. Martire, S. A. Wise, J. Chromatogr.442, 1 (1988).
A. Lowenschuss, N. Yellin, Spectrochim. Acta31A, 207 (1975).
K. L. Rowlen, J. M. Harris, Anal. Chem.63, 964 (1991).
E. D. Katz, K. Ogan, R. P. W. Scott, J. Chromatogr.352, 67 (1986).
L. R. Snyder, J. Chromatogr. Sci.16, 223 (1978).
J. L. Glajch, J. H. Kirkland, K. M. Squire, J. M. Minor, J. Chromatogr.199, 57 (1980).
W. R. Melander, C. A. Mannan, Cs. Horvath, Chromatographia15, 611 (1982).
W. R. Melander, B. K. Chen, Cs Horvath, J. Chromatogr.282, 107 (1983).
W. J. Cheong, P. W. Carr, J. Chromatogr.499, 373 (1990).
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Guillaume, Y., Guinchard, C. Marked differences between acetonitrile/water and methanol/water mobile phase systems on the thermodynamic behavior of benzodiazepines in reversed phase liquid chromatography. Chromatographia 41, 84–87 (1995). https://doi.org/10.1007/BF02688004
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DOI: https://doi.org/10.1007/BF02688004