MICHROM softwar

Torres-Lapasio, J.R. Michrom Software-, Cazes, J., Ed. Marcel Dekker, Inc. New York, 2000. 

True micellar phases (surfactant + water) can be considered mobile phases with low elution strength. If organic modifiers, mainly alcohols, are added in small proportions to the micellar phases, a significant enhancement of the efficiency as well as elution strength is observed. Chapter 7 is dedicated to this topic. When micellar solutions and/or hybrid micellar phases with alcohol additions are used as mobile phases, it is possible to accurately predict the retention of each compound in a mixture. This capability is more decisive than in conventional RPLC because the MLC peaks are broader. The elaborated equations for modeling and optimization purposes given in Chapter 8 are easily applied with the aid of the MICHROM software included with this book. Appendix I is given as an aid to run the software. 

The main effect of alcohol addition to a micellar phase is the increase of elution strength as reviewed in Chapters 7 and 8 and modeled by the MICHROM software (see Appendix I and attached CD-ROM). The decrease of the P values observed for the apolar compounds (Table 6.4) can be generalized to any solute. These effects are related to thermodynamics. The kinetics of the chromatographic process is also affected by the addition of alcohols to the micellar phases. 

The reader should not be repulsed by the somewhat complex equations developed in this chapter. They are incorporated in the MICHROM software supplied with the book. Appendix I describes the computer assisted way to model the retention behavior of a given mixture in MLC. With a few guided experiments, the software will be able to model the retention of an actual mixture components with surprising accuracy. 

IX. EASY MODELING AND OPTIMIZATION IN MLC WITH THE MICHROM SOFTWARE... 

Further optimization of mobile phase composition (SDS and 1-propanol concentration) was made using the method developed by Torres Lapasio et al. [40], assisted by ih MICHROM software (see attached CD ROM). Maximum resolution corresponded to 0.042 M SDS-4% 1-propanol. Fig. 11.8 shows the experimental chromatogram for this mobile phase of a urine sample spiked with a mixture of the diuretics, together with a similar chromatogram obtained with an aqueous solution. The retention times for both chromatograms were similar. The peaks of amiloride and xipamide, on the one hand and triamterene and spironolactone on the other, appeared mutually overlapped in the chromatograms. The peak of bendroflumethiazide was overlapped by the prominent peak of urine. 

The MICHROM software was written exclusively for this volume by Jose Ramon Torres-Lapasio, University of Pamplona, Spain. 

The enclosed CD-ROM contains everything needed to run MICHROM. This software is able to take the results obtained with a set of compounds and several compositions of hydro-alcoholic micellar phases, and calculate the affinity constants to predict the results for compositions of mobile phase (surfactant concentration, modifier concentration and pH). 

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