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Optimal experimental designs for estimating Henry's law constants via the method of phase ratio variation.

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Title: Optimal experimental designs for estimating Henry's law constants via the method of phase ratio variation.
Authors: Kapelner, Adam1 kapelner@qc.cuny.edu, Krieger, Abba2 krieger@wharton.upenn.edu, Blanford, William J.3 william.blanford@qc.cuny.edu
Source: Journal of Chromatography A. Oct2016, Vol. 1468, p183-191. 9p.
Subjects: Henry's law, Optimal designs (Statistics), Gas chromatography, Volatile organic compounds, Regression analysis, Experimental design
Abstract: When measuring Henry's law constants ( k H ) using the phase ratio variation (PRV) method via headspace gas chromatography ( G C ), the value of k H of the compound under investigation is calculated from the ratio of the slope to the intercept of a linear regression of the inverse G C response versus the ratio of gas to liquid volumes of a series of vials drawn from the same parent solution. Thus, an experimenter collects measurements consisting of the independent variable (the gas/liquid volume ratio) and dependent variable (the G C − 1 peak area). A review of the literature found that the common design is a simple uniform spacing of liquid volumes. We present an optimal experimental design which estimates k H with minimum error and provides multiple means for building confidence intervals for such estimates. We illustrate performance improvements of our design with an example measuring the k H for Naphthalene in aqueous solution as well as simulations on previous studies. Our designs are most applicable after a trial run defines the linear G C response and the linear phase ratio to the G C − 1 region (where the PRV method is suitable) after which a practitioner can collect measurements in bulk. The designs can be easily computed using our open source software optDesignSlopeInt , an R package on CRAN . [ABSTRACT FROM AUTHOR]
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Database: Engineering Source
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Abstract:When measuring Henry's law constants ( k H ) using the phase ratio variation (PRV) method via headspace gas chromatography ( G C ), the value of k H of the compound under investigation is calculated from the ratio of the slope to the intercept of a linear regression of the inverse G C response versus the ratio of gas to liquid volumes of a series of vials drawn from the same parent solution. Thus, an experimenter collects measurements consisting of the independent variable (the gas/liquid volume ratio) and dependent variable (the G C − 1 peak area). A review of the literature found that the common design is a simple uniform spacing of liquid volumes. We present an optimal experimental design which estimates k H with minimum error and provides multiple means for building confidence intervals for such estimates. We illustrate performance improvements of our design with an example measuring the k H for Naphthalene in aqueous solution as well as simulations on previous studies. Our designs are most applicable after a trial run defines the linear G C response and the linear phase ratio to the G C − 1 region (where the PRV method is suitable) after which a practitioner can collect measurements in bulk. The designs can be easily computed using our open source software optDesignSlopeInt , an R package on CRAN . [ABSTRACT FROM AUTHOR]
ISSN:00219673
DOI:10.1016/j.chroma.2016.08.049