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620. SIMUL: A General Program for the Simulation of
Chromatograms Using the Theoretical Plate Model
by Martin Jung, Institute for Organic Chemistry, University of Tübingen, W-7400 Tübingen, Germany For all solutes, theoretical plate numbers and retention times are input as a basis for the correct simulation of peak widths and retention. The number of solutes is not limited, and they may be injected in different amounts and have different theoretical plate numbers. The solutes are "injected" into the mobile phase of the first plate, then equilibration between mobile and stationary phase takes place, the solutes are allowed to perform reactions among each other, and finally the mobile phase is shifted forward to the next plate and so on. Reactions during chromatography are allowed and treated strictly separately from the rest of the program in the subroutines REACT1 to REACT5. In the program SIMUL, these subroutines simulate the racemization of the enantiomers 1 and 2 during chromatography with different rate constants for mobile and stationary phase, but SIMUL can also be used for the simulation of "normal" chromatograms if the rate constants of racemization are entered as zero. By modifying only the subroutines REACT1 to REACT5, the program can easily be adapted to other problems concerning reactions during chromatography. This has been done in the program SIMULX which is identical with SIMUL except for these subroutines. Here, an example is presented as to how to describe a more complicated system using the Runge-Kutta method for the calculation of the reaction kinetics: The enantiomers R and S undergo dimerization so that, in addition to monomeric R and S, the (diastereomeric) dimers RS, RR and SS may be present. The chromatograms are output in a digitalized form. The program REDUCE reduces the size of the output file to a reasonable amount of data (about 20-100 Kb per chromatogram), since the original output files may be very large, depending on the theoretical plate numbers entered. At this point it is suggested that one transfer the chromatogram files to a personal computer and use commercial software for the plotting. Additional small conversion programs will be needed to adapt the files to the format of the particular program to be used. It is, however, hardly possible to use the simulation program itself on a PC, since the calculations would take much too long. The CPU time needed greatly depends on the theoretical plate numbers which determine the number of loops needed. NOTE:This program uses a feature which, while not totally uncommon, is somewhat unusual. It contains FORTRAN statements which are longer than 72 columns. This is important for two reasons: * We can only distribute it in VAX COPY (ANSI D) or TAR format. * The user has to be aware of the above feature and inform the FORTRAN compiler of the use of the extended line in order to obtain a successful compilation. Lines of Code: 2332 FORTRAN (CONVEX) |