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GC/qTOF – the Best Way to Screen for Legal Highs?

Martin Perkins

12th June 2013


 

Agilent 7200 GC/q-TOF and GERSTEL Multi-Purpose Sampler
Agilent 7200 GC/q-TOF and GERSTEL Multi-Purpose Sampler

How do you analyse for something when you don’t know what it is you are looking for?

As a rule, in Clinical LC/MS, you know exactly what compounds you are looking for – you simply have to measure the amount present in the sample.

When analysing a sample from a patient suspected of taking a legal high, you don’t know for certain what substance you are looking for, you may not have a standard to compare with and on many occasions the drug will be something you haven’t previously encountered – you may have some clues to its possible identity of course, but applying traditional target analytical approaches, will result in missing as many compounds as you find.

Triple quadrupole mass-spec is generally regarded as the “gold standard” of clinical analysis. It is brilliant at selectively targeting known compounds in complex biological matrices, however, it is the wrong tool for this job.

Instead you need something different. A GC/Quadrupole–Time of Flight Mass Spectrometer (GC/q-TOF).

Why is that?

A triple quad can be compared to a microscope – great at focusing on one thing,  but useless if you don’t know where to look. Using this analogy, a q-TOF does two things and can be used in two ways, firstly, like a pair of binoculars to scan for unusual substances, secondly, as a very powerful microscope, to examine the things you do find in great detai.

In TOF mode, a GC/q-TOF acquires the whole mass spectral data set from your sample (yes, the data files are huge) and so enables you to search for things that shouldn’t be there. Once you do find something, then the GC/q-TOF’s high mass spectral resolution enables you to work out possible empirical structures for the mystery compound (or at least focus on a small number of possible candidates). If the compound doesn’t have an entry in a mass-spec library, you can still gather valuable information on its identity.

When you do have ambiguities in the identity of a compound from accurate mass TOF data, you can resort to q-TOF mode. This switches-in a qualdrupole mass filter and collision cell, ahead of the flight tube, this lets you apply accurate mass TOF to the product ions from the unknown analyte, and you can often resolve ambiguities that way.

The Agilent GC/q-TOF is a very powerful instrument that is probably the best tool currently available for coping with the analytical challenges of legal highs in biological matrices.

Here at Anatune, we have just taken delivery of an Aglilent 7200 GC/q-TOF and this will be up and running in our Cambridge laboratory shortly.

We will be selling this instrument to customers as part of an analytical solution that couples the GC/q-TOF with a GERSTEL Multi-Purpose Sampler. This combines the 7200 with the best and most flexible sample prep automation package available and will come with a full Anatune Assist support package to cover, not only the instrumentation and software, but also application and training support as well.

If legal highs represent an analytical challenge to you, we would like to learn from your experience. Please accept this invitation to visit our lab in Cambridge and we will explore what this approach has to offer you.

We expect to be ready to demonstrate our system from mid-July onwards. To arrange a date, please call us on 01223 279 210 or email enquiries@Friiscan.co.uk