Friday, 3 July 2015

Learning by Competition, by Falko Drijfhout

To enhance student engagement and interaction between students, I have started to make use of a small competition run during a lab session for second year Forensic Science students. In the corresponding module students need to solve a chromatographic problem, i.e. increase separation and efficiency of a method.

After students spend a lab session learning the basic principles of a gas chromatography and the importance of temperature programming, they are given a sample with seven compounds and an example chromatogram of an isothermal GC-analysis. Students are required, with a limited amount of time and trials, to improve the method from an isothermal analysis to a programmed temperature analysis with good resolution, but in the shortest possible time. The instructions given to them are shown below:


Experiment 1C: Optimisation of GC separation
(internal competition)

An example chromatogram (see Fig. 1) shows the results of an isothermal (80°C) analysis of the mixture of 7 compounds. Although all compounds are well separated, the analysis time is quite long.

Figure 1. Chromatogram of the isothermal analysis of mixture B

It is your task to develop a method through temperature programming to separate out all 7 compounds in the shortest possible analysis time. How you develop your method is all up to you as a group. The group who managed to get the best separation and the shortest analysis time will receive a prize!

Aim of this session:
In this laboratory session you will be able to
  • apply the knowledge of the lectures and lab session 1 to solve a problem 
  • develop your own method in which your aim is to separate out all 7 compounds within a mixture in the shortest possible analysis time 
  • achieve a resolution of minimal 1.5 (baseline separation) between peaks 2/3 and 4/5

Develop a programmed oven temperature program that is most suitable for the analysis of mixture B containing the 7 compounds.

1) What GC parameters can/should be varied
  • Initial oven temperature 
  • Hold 
  • Temperature ramp(s) 
  • Final oven temperature
2) Rules
  • You are only allowed to inject your sample a maximum of 3 times! 
  • Maximum final oven temperature is 270°C 
  • A good separation means that all resolutions should be at least 1.50 
  • Analysis time = retention time of the last compound
3) Remember:
  • Only inject when the GC is in ‘ready’ status 
  • Start the GC temperature programming at the same time as the data collection on LoggerPro 
  • You will need to present your method in a short presentation.

~~ Good Luck!! ~~


In developing their best method, they need to consider the theory and their discussions help them to use their newly obtained knowledge in solving the problem of inefficient chromatography. My experience with this approach in a lab session is that students are much more engaged in discussing their methods within their group. As they discuss how a new method may affect their chromatography they impart knowledge from one to the other and weaker students are helped in their understanding. It also gives me an opportunity the spot any misconceptions students may have, by listening to their discussions. I noticed an increase level of noise (due to increased and intensified discussions) during the lab sessions as they see the effect of a changed method, or as they want to win from peers.

I do this in the beginning of the module (week 2 or 3) and it does help to get students to discuss problems with each other or with me throughout the module.

Creative Commons License
Learning by Competition by Falko Drijfhout, Keele University is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.