Simulations and Virtual Laboratories in Chemistry Education

1
Simulations and Virtual Laboratories in
Chemistry Education Jetse Reijenga Eindhoven
University of Technology, the Netherlands

• Summary
• Chemistry education is particularly expensive
  because of the need for advanced laboratories
  with complicated equipment, chemicals and safety
  precautions. Naturally, these facilities are
  often shared with research staff, but that
  doesnt make it any easier accommodating tens of
  students or more, performing identical
  experiments in a limited time frame. Experiments
  in education however are essential. During the
  past decades, we have been able to show 1 that
  experiment simulations and even virtual
  laboratories can provide a valuable addition to
  the experimental part of the study. Several
  examples in the field of analytical
  instrumentation (chromatography and
  electrophoresis) will be illustrated.
• Introduction
• When embedding simulations in a curriculum, we
  suggest following approach
• Theoretical basics are taught in lectures and
  self-study format. Most simulators can generate
  useful illustration material and demos.
• Students then perform a few simple introductory
  experiments on preset equipment, largely to
  illustrate the order of magnitude of samples
  handled, of the time needed to carry out the
  experiment, and to appreciate the complexity of
  expensive equipment.
• Finally, students are given simulation
  assignments, e.g. systematically changing one or
  more parameters, and drawing conclusions from the
  results. An advanced assignment might involve
  optimizing a difficult separation, using several
  parameters.
• Results and Discussion
• The default screen layout of simulators for
  analytical separation instruments consist most
  often of a menu and a chromatogram (detector
  signal vs. time) as depicted in the figures
  below.

Simulation programs for capillary electrophoresis
are also available. HPCESIM was published in 1994
6. Options for illustrating chiral separation
were added in 1997. The program plots of
selectivity vs pH for easy method development and
offers possibility to study the effects of
temperature on efficiency.
More recently, a sophisticated windows version
(Peakmaster) was published by Bohuslav Gas of
Prague University 7. This one is very
user-friendly and has a huge easily editable
sample data base. Complications such as ghost
peaks, occurring when using certain background
electrolytes, are also featured.
Whereas all of the aforementioned simulators
generated detector signals after separation,
dynamic simulators such as SIMUL 7 generate
concentration profiles in the separation chamber
at small time intervals. We can thus monitor on a
micrometer scale how separations develop locally.
Valuable insights for advanced users!
On the left, the output of a gas chromatography
simulator 2, n-alkanes in a linear gradient on
a non-polar capillary column. The simulator has 2
stationary phases, 2 detectors and 5 carrier
gasses, enabling in finite number of hypothetical
separations. The program features many other
output screens, e.g. van Deemter plots and
detailed plate height info.

• Virtual Laboratory
• Obvious synergy can be achieved by combining
  simulators of different instruments in solving a
  hypothetical analysis problem. A very
  sophisticated integration of numerous techniques
  is ProteinLab 8 by A.G. Booth of Leeds
  University. It is a simulator dedicated to
  isolate and identify a protein from a mixture of
  20, and features the following techniques
• Heat treatment
• Ammonium sulphate precipitation
• Gel filtration
• Ion-exchange chromatography
• Hydrophobic interaction chromatography
• Isoelectric focusing
• Affinity chromatography
• HPLC
• SDS-PAGE
• Two-dimensional electrophoresis

On the right, the output of a HPLC simulator
3, a mixture in a reversed phase water-methanol
gradient also shown are curved solvent viscosity
and pressure drop traces (maximum for
water/methanol). This simulator has 2 solvent
modifiers, 2 detectors (including diode array)
and 6 column types (among which a
state-of-the-art monolith column).
This is a simulator for Permeation Chromatography
simulator 4 for SEC of polymers. It includes 21
different polymers, 12 types of columns and 5
detectors, including novel Charged Aerosol. The
example on the screen illustrates the need for
using universal calibration with K and a values
from the Kuhn-Mark-Houwink-Sakurada viscosity law.

• Conclusions
• Prior basic knowledge of techniques still
  required as the programs are not self-contained
  tutorials, but the programs can also be used in
  classroom demonstrations, and to generate example
  illustrations for textbooks. I even used
  ProteinLabs once in an exam setting. Valuable
  insight into theory and an enormous time-gain can
  be obtained in organizing dry-lab practicals.
• Powerful instrument simulators are available for
  all analytical separation techniques. All
  examples mentioned are available as free
  download, or can be obtained from the author on
  request. Why not give it a try?!
• References
• http//edu.chem.tue.nl/ce
• J.C. Reijenga, J. Chromatogr., 1991, 588, 217-224
  
• J.C. Reijenga, J. Chromatogr. A, 2000, 903, 47-54
• J.C. Reijenga, W.J. Kingma, D. Berek, M. Hutta,
  Acta Chim. Slov. 2007, 54, 79-87
• J.C. Reijenga and M. Hutta, J. Chromatogr. A,
  1995, 709, 21-29
• J.C. Reijenga and E. Kenndler, J. Chromatogr. A,
  1994, 659, 403-415 and 417-426.
• http//www.natur.cuni.cz/gas/
• http//home.btconnect.com/agbooth/archive/

Another technique, combining chromatographic and
electrophoretic principles, is called micellar
electro-kinetic capillary chromatography 5. The
(un)charged sample components migrate within a
time window (between t0 and tm), in increased
order of hydrophobicity (in sequence reversed
from RP-HPLC). In the example given, the whole
range of retention factors from zero to infinity
is shown.
j.c.reijenga_at_tue.nl - 20th ICCE Mauritius 2008