shutterstock_338015993I need you to vote on this issue using the vote buttons below! A discussion has broken out amongst a group of us here at Thermo Fisher Scientific as to whether a Low-Pressure Gradient (LPG) or High-Pressure Gradient (HPG) pump in your liquid chromatography system is the better option for mass spectrometry, or does it not really matter?  In our discussion, a small majority was on the side of the HPG, however the LPG did have its advocates. But what is your opinion? Before you vote below, though, let me outline the case for both pumps.

HPG, Binary, Pump for LC-MS

The main benefit and reasoning for using an HPG pump for LC-MS is that such pumps typically have a small Gradient-Delay Volume (GDV) and hence less dispersion than an LPG pump, which allows for faster methods, reduced total analysis time and increased throughput, allowing many more samples to be run per day.

LPG, Quaternary, Pump for LC-MS

As indicated above, an LPG pump typically has a greater GDV than an HPG pump, but when dealing with longer gradients, for example above 20-30 minutes, this increased GDV becomes almost insignificant. So if you are performing longer runs, then an LPG will give as good LC-MS results as an HPG pump, but with the benefit of, on average, being cheaper to purchase and maintain than an HPG pump. However, probably the major benefit of using an LPG pump is being able to use ternary and quaternary gradients and multiple solvents; however this in not always necessary in LC-MS.

HPG or LPG – It Doesn’t Matter

Perhaps there is a third option in that for most applications it doesn’t actually matter or people don’t have a preference for either an HPG or an LPG pump. The mass spectrometer is the key element in the workflow and the HPLC instrument is there to just deliver the sample to the mass spectrometer. So as long as it does that then I don’t really concern myself whether it’s an HPG or LPG pump.

Time to Vote!

What is your preference regarding the type of HPLC/UHPLC pump for your mass spectrometry? Are you an HPG or an LPG pump advocate or do you have no preference? I’ve outlined the case for each scenario above, but now give us your opinion by clicking the appropriate button below to register your vote:

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Thanks for your vote, keep checking back in to see if the distribution changes as more votes are cast. Please also feel free to elaborate on your choice in the comments box below and indicate what your primary market is (e.g. food, safety, pharmaceutical, etc.).