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Internet Electronic Journal of Molecular Design - IEJMD, ISSN 1538-6414, CODEN IEJMAT
| ABSTRACT - Internet Electron. J. Mol. Des. March 2004, Volume 3, Number 3, 150-162 |
A Combinatorial Protocol in Multiple Linear Regression to Model Gas
Chromatographic Response Factor of Organophosphonate Esters
Yenamandra S. Prabhakar
Internet Electron. J. Mol. Des. 2004, 3, 150-162
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Abstract:
Organophosphorus compounds are a well known class of toxic
chemicals which find their way into ecosystem due to their wide
spread use. Their detection, identification and quantification are
cause of concern world over. In environmental samples these
compounds are detected and estimated through the gas
chromatographic response factor. This prompted us to study the
quantitative structure-response relationships (QSRR) of gas
chromatographic response factor of organophosphonate esters. In
this study attempts have been made to rationalize the gas
chromatographic response factor of twenty-eight
organophosphonates in terms of their physicochemical and
electronic descriptors. Combinatorial Protocol in Multiple Linear
Regression (CP-MLR), a 'filter' based variable selection procedure
for model development in structure-activity or property
relationship studies, has been used for the variable selection and
identification of diverse QSRR models of the GC response factor
of organophosphonates. The study has resulted in the identification
of ten models (equations), having two or three descriptor each, to
account for the response factor of organophosphonates
(cross-validated R2 or Q2 is 0.88 to 0.95).
The response factor of the
compounds is strongly correlated with the total refractivity
(TREF), molecular weight (MW) and thermodynamic properties,
e.g., enthalpy of vaporization (ENTH). In the study, alkyl groups
of these compounds have shown two-fold influence (namely, steric
and branching effect) on the response factor. Also, the study
suggests that the polarization of (d-p)π bond of P=Oa in these
compounds plays a critical role in the formation of the responding
species. The steric and electronic properties of
organophosphonates play a determining role in the predictive
aspect of their gas chromatographic response factor. Also the study
suggested a mechanism for the formation of the responding
species.
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