“Can you take a quick look and tell me what’s in this?”
Posted on January 11th, 2012
How many times have you been asked that question?
Assuming the “what” is a small organic molecule, then GC-MS is the tool that you would probably turn to, but you can easily come to grief with the sample preparation and introduction, since the most appropriate choice is dictated by a combination of:
- the sample matrix
- the analyte
- its expected concentration
- other interfering compounds
There is never a shortage of different techniques that can be applied – all with there own unique attributes. The chances are that one of them will work, but you are always limited by the sample preparation instrumentation that you have in the lab.
If the aim is to cover all options, you could equip yourself with an array of dedicated sample preparation instrumentation and multiple GC-Mass Spectrometers to hang it all on, but this would be a very expensive exercise, and much of the instrumentation would be idle for most of the time.
There is another (more realistic) approach.
It uses common XYZ robotics for automation (which keeps total costs down) and can easily support a multitude of different preparation and injection technologies to be used with a single GC-MS.
Swapping between different techniques is quick and easy to do – so you can quickly identify the most appropriate sampling/injection technology for your current analytical task.
Dan Carrier, is one of our application chemists and was recently faced with exactly this situation. Dan needed to survey a number of pre-concentration techniques to see which one would provide the most information about the composition of a popular herbal liqueur. The techniques investigated were:
- Static Headspace
- Dynamic Headspace
- Twister (Stir Bar Sorptive Extraction)
All of these were run on the same GC-MS equipped with a GERSTEL Multi-Purpose Sampler and Dan was able to readily change from one sampling mode to another.
If you take a look at the application note that Dan has written, you will see how different the chromatograms look and see why it is important to have lots of different tools in your sample preparation tool-kit (to read the application note, follow the link in the email that directed you here).
When you plan to renew or upgrade your current GC-MS, you would be wise to review your current and future sample preparation requirements and think about adding a GERSTEL MPS into the budget, since this will greatly expand your sample preparation options and make it much less likely that you will get caught out.