Things you can do with a MultiFlex (No.2) – Hot Injection and Trapping (HIT)

Martin Perkins

5th November 2013

Performing Hot Injection and Trapping (HIT)

Imagine that you are developing a GC-MS method and you find that you are having trouble achieving a sufficiently high loading of analyte in the column.

One simple way of solving the problem would be to introduce multiple aliquots of the same sample into the instrument, such that you could enrich the sample in the instrument’s inlet – in effect, trapping each successive injection and stacking the injections upon each other, before injecting them onto the column simultaneously.

The MultiFlex lets you do this.

The GERSTEL MultiFlex is a flexible sample introduction and automation system that comprises a GERSTEL Cooled Injection System (CIS4), Thermal Desorption Unit (TDU) and MultiPurpose Sampler (MPS).

With the MultiFlex, the TDU couples directly to the CIS4 inlet and has all of the capability to be used as a fully temperature and flow programmable inlet in its own right. This means that the CIS4 injector, which is mounted below the TDU, can be kept at a low temperature during the injection process, cold trapping analytes as they emerge from the TDU.

Indeed, the CIS4 can be kept cold while several injections are made into the TDU.

This family of injection techniques is called Hot Injection and Trapping (HIT) and can be best thought of as a way of separating the injection of the sample, from the process of focusing the analytes on the head of the column.

This brings us some useful additional flexibility when it comes to matching the amount of analyte we place onto the column to the dynamic range of our detector (ideally, we would like to have our top standard just below the point where our detector saturates or departs from linearity).

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.

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.

Needless to say, you just don’t get these options with a standard liquid autosampler and split/splitless inlet. It is by opening up these possibilities, that the GERSTEL MultiFlex earns its keep.

If you would like to know more what the GERSTEL MultiFlex has to offer, or to see one in our Cambridge laboratory, please call us on 01223 279210 or email