Hadjmohammadi MR, Kamel K, Fatemi MH. Optimization of the separation of chlorophenols with stepwise gradient elution in reversed phase liquid chromatography.
J Sep Sci 2007;
30:2687-92. [PMID:
17763519 DOI:
10.1002/jssc.200700095]
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Abstract
An optimization technique based on gradient elution was used to separate eleven chlorophenols by reversed phase liquid chromatography. The separation was based on gradient elution with a stepwise variation pattern of the volume fraction of organic modifier, phi, in the mobile phase. Initially, two-, three-, and four-parameter equations which describe the dependence of ln k' upon phi, were examined for their ability to fit the experimental data. It was found that, among these equations, the four-parameter equation gave the best fit of the experimental data. In addition to separation optimization, a non-linear least squares program with a grid search for initial estimates was used to determine the best variation pattern. The best variation pattern was obtained with phi(1)= 0.27, phi(2)= 0.39, phi(3)= 0.62, t(1) = 33 min, and t(2) = 11 min. This pattern allowed the chromatographic separation of the chlorophenols with a good resolution and a total analysis time of 51 min. Good agreement was observed between predicted and experimental values of the retention times under optimal condition.
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