Elke Below

Theoretical treatment of first-order reversible reactions occurring in a chromatographic reactor, on the basis of consecutive reactions

SummaryAnalytical peak-shape equations were derived for first-order reversible reactions occurring in a chromatographic reactor by treating the reversible reactions as consecutive reactions with alternating products. The results of the analytical peak-shape equations were compared with those from a numerical solution of the partial differential equation system modeling the chromatographic reactor. For small to medium conversions the correspondence was found to be sufficiently close to enable substitution of the numerical solution in fitting procedures for the determination of rate constants.

Parametric Studies on the Determination of Enantiomerization Rate Constants from Liquid Chromatographic Data by Empirical Peak Shape Equations for Multi-Step Consecutive Reactions

On-column enantiomerization is a well documented and practically important special case of the occurrence of a reversible reaction in a chromatographic reactor. The present paper explains the possibility to obtain enantiomerization rate constants from liquid chromatographic data using analytical equations derived for multi-step consecutive reactions. The results are compared with results from a finite difference method, and the application to experimental data is demonstrated.

Autocatalytic reactions in a liquid chromatographic reactor

The possibility of extending the treatment of second-order on-column reactions with two different reactants by empirical peak shape equations to autocatalytic on-column reactions was investigated. An approximate analytical solution is presented, which for small to medium conversions agrees with the solution of the ideal non-equilibrium model of chromatography by a finite difference method.

Determination of rate constants of consecutive first order reactions occurring on chromatographic columns

Abstract Approximate analytical equations were developed for the products of consecutive reactions occurring on a chromatographic column. The equations were tested both by numerically evaluated chromatograms and the acid catalyzed hydrolysis of phthalic dichloride in a liquid chromatographic reactor.

Application of HPLC Equipment with Rapid Scan Detection to the Identification of Drugs in Toxicological Analysis

Abstract The paper reports on an application of HPLC equipment with rapid scan detection, in which the UV-spectra recorded by the rapid scan detector are used for drug identification. A dBase database was set up, utilizing the retention data of a drug substance in a neutral and an acidic HPLC solvent together with the related UV spectrum. The identification of an unknown drug is supported by a home made search program, comparing the retention times first and then examining the maxima of UV spectra. The data base presented here contains more than 200 entries, and data of additional substances are continuously attached. It provides a fast and low cost possibility for the assay of drugs and medicaments in biological matrices and is especially used in emergency analysis.

Determination of rate constants in a liquid chromatographic reactor by means of a fitting algorithm

Abstract Based on the exponentially modified Gaussian profile, a new equation for the evaluation of product peaks of liquid chromatographic first- order reaction chromatograms is given. It is shown that this equation is able to fit reaction chromatograms corresponding to the linear model of chromatography.

Separate Determination of Mobile‐Phase Rate Constants for Reversible Reactions

Abstract The application of a mathematical‐analytical chromatogram‐equation is demonstrated for reversible on‐column reactions with different forward and backward rate constants using simulated recycling via an empty capillary. The method was successfully tested with numerically evaluated chromatograms and experimental chromatograms from the cis–trans‐isomerization of L‐leucyl‐L‐proline (Leu‐Pro). #This work is dedicated to the 65th Birthday of Prof. Dr. Detlef Haberland.

Chromatograms of second-order reactions on chromatographic columns

Abstract The application of the EICR model to several second-order reactions in a gas chromatographic reactor is demonstrated. Reaction gas chromatograms were obtained and rate constants were evaluated. With the rigid EICR assumptions, which, however, are more realistic than the ICR assumptions, at least the estimation of second-order rate constants becomes possible in a fairly simply way, requiring only a knowledge of retention times, half-width values, pulse areas and inlet amounts of the reactants.

DETERMINATION OF ADSORPTION ISOTHERMS BY THE INVERSE METHOD WITH A FIRST ORDER REVERSIBLE REACTION OCCURRING IN BOTH PHASES OF A LIQUID CHROMATOGRAPHIC COLUMN

The determination of rate constants and isotherm parameters by the inverse method is described for a first order reversible reaction. The application of the principle of microscopic reversibility is discussed for competitive isotherms. Experimental data are obtained from the enantiomerization of oxazepam.