Chromatography Forum

Currently, my company plans to buy a LCMS. So far we have a little bit of hard time to decide to have a TOF or a QQQ. Our goal is to use a LCMS to cover confirming (quantitative) and screening (qualitative) in pesticides and drugs in water and produce/food. Typically, TOF is for screening, QQQ for confirming. My questions: 1) can TOF do quantitative analysis as good as QQQ? 2) Can QQQ do qualitative analysis? So far, money is not what we concern. But Q-TOF is too expensive to us.
Thanks a lot!

I would define the differences as follows. QQQ is for looking for known compounds, Q-TOF is for looking at unknowns. If you want to screen, identify and quantitate target compounds then a QQQ will fit your requirements best. For these applications you will only buy a Q-TOF if you need to look for unknowns as £ for £ a Q-TOF will not match a QQQ for target work. Q-TOFs are great for unknowns as you always get the equivalent of full scan data and you can always go back and target compounds you did not look for first time round without re-running the sample. Q-TOF will also give accurate Mass determination for additional conformation and better identification of unknowns.

May I suggest QQQ-trap. You can purchase it as qqq and upgrade later to trap.

It is mid way in price and identification capability from qqq to tof. Or I should say complimentary capability. And you can completely disable trap function for some runs when you don’t need it, if you wish. Brand is used by some EU authorities for residue work.

I read some vendor's introduction materials, it seems ion trap can do both quantitative and qualitative analysis. Anyone has suggestion on ion trap?

In my experience, all type of mass spec can be do both qualitative and quantitative analysis depend on your requirements.
If you need to improve analyte(s) sensitivity down to pg-fg level, QQQ and QTRAP and some 3D Ion Trap is the best for quant.
If you need to quantitate with wide dynamic range, QQQ and QTRAP is better.

For TOF and QTOF in my work, it good for wide range of substances screening (large numbers of substances can be done with TOF or QTOF better than QQQ) and also can do quantitative analysis but not good in term of linear range (4-5 order of magnitude, QQQ shown 6-7 order)