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Sample Introduction for High Performance Mass-Spec

Martin Perkins

16th May 2013


 

Hot Injection and Trapping

If you are investing in an expensive high-performance GC/MS, it makes no sense to economise on sample introduction.

While you will take great care in selecting an MS that is a good match for your needs, it is just as important to think carefully about your sample introduction requirements. If you do go beyond a standard liquid autosampler and split/splitless inlet, with more capable sample introduction hardware, you can greatly expand the capabilities of your magnificent new instrument.

The truth is that high-performance mass-specs attract all kinds of thorny analytical problems that you will be expected to solve.

Any analyte, any concentration, any matrix.

Flexibility in sample introduction matters too; You don’t want to be venting and thermally cycling the MS every five minutes as you change from one sampling accessory to another. It’s easy to get caught out with this and end up wasting lots of time reconfiguring and then troubleshooting hardware.

Shortly we will be installing an Agilent 7200 GC/qTOF in our laboratory, and these are realities that we also will have to face. Our customers decide on the problems we have to tackle, and few are easy ones to solve.

The 7200 will be by far the most powerful MS we have ever run and while waiting for the instrument to be delivered, we have been thinking hard about the optimum sample introduction set-up to use with it.

We have settled on a GERSTEL automation and sample introduction package that uses the LN2 cooled CIS4 inlet, TDU with automated tube exchanger and a dual-head Multi-Purpose Sampler.

You can get some idea of the capabilities from this video.

This will give us the widest possible range of sampling options – including a lesser known one that we think will be be especially useful: Hot Injection and Trapping (HIT).

HIT is a way of separating the injection of the sample, from the process of focusing the analytes on the head of the column. This will do two big things for us:

  1. For both liquid and gas phase samples, we will be able to inject a much wider range of sample volumes, so it will be much easier to get the right amount of analyte into the column under all circumstances.
  2. It lets us limit the amount of high-boiling material that gets into the system from dirty or complex samples.

If you can spare five minutes or so, the video will give you a good idea of what is possible. HIT with solids and liquids, features at the 3.4 minute mark.

We have included the dual-injection head capability as this will give us the ability to auto-spike samples (better precision and less work) and good liquid handling (more complete automation of the sample prep).

Since there will be plenty of data for our lab staff to crunch – the more we can automate the sample preparation and introduction, the more work we can get done.

If you are facing sample prep limitations on your GC-MS or would like to see what is possible with the next GC-MS you plan to buy, please call us on 01223 279 210 or email enquiries@anatune.co.uk.