Dear all,
We want to purchase a LC-MS for our lab of bioanalytics, where the main application is the determination of drugs and some metabolites in plasma samples for pharmacokinetic-biavailability-bioequivalency studies.
I'm currently using GC-MS and LC (Agilent) with UV, FLD and ECD detectors but honestly, I'm a complete beginner in LC-MS.
I'd like to get some input of information from real users and not only from vendors.
We need high sensitivity and selectivity and I'd really appreciate any help.
Thanks in advance

Marcelo

Marcelo,

If you wish to do only quantitative measurements you will need triple quadrupoles instruments which provides the highest sensitivities and dynamic ranges. In my opinion the two best are the API-4000 (applied biosystems) and Ultima II (Micromass).

If you want to identify your metabites then you should buy a hybrid quadrupole-time of flight instrument which will help you due to their high resolution (accurate mass) capabilities. For the moment the problem with the TOF instruments is their limited dynamic range (2-2.5 orders of magnitude) so if you want to do both I would recommend that you purchase one Triple quadrupole and one quadrupole time of flight. Applied biosystems and micromass have some very nice instruments as well.

I hope that others will reply and propose more LC-MS instruments that may be adequate for your work.

Kostas

Kostas
Thank you for you reply. Yes, most of our routine is drug quantitation in a large number of samples (I'd say 99% of the work).
Any opinion about single quad or ion trap instruments (that some vendors are offering) ?

Regards

Marcelo

There are some issues about the ion traps and quantitative measurements so I wouldn't recommend an ion-trap for that.
Single quadrupoles can do the job, but then again you limit your specificity (and I can garantee you that you need all the specificity that you can if you work with plasma/biological fluids).
Furthermore, a single quadrupole analysis is 10 to 100 times less sensitive than a triple quadrupole analysis (depending on the fragmentation of your compound of interest).

Kostas

Marcelo,

For quantitation purposes, I think that triple quadrople MS are the best option. You should consider the Thermo Finnigan TSQ Quantum. From our experience the Quantum can achieve sensitivity comparable to the 4000 or ultima. But the Quantum has also high resolution capabilities which maybe useful if you have some specificity problems.

Good Luck!

Thank you for your help, Anonymus and Kostas.
Best regards.

Marcelo