Friday, March 30, 2018

More evidence, finally -- is it time to question the dogma of the nanoLC?

If you want to identify a protein in a gel spot on an LCQ Deca or QTrap -- you need nanoLC. You just don't get enough signal from your 100 bar Accela LC running 200 (+/-40) uL per minute into that big round ESI source that has the 11 things you have to attach to it.  If you want to identify that gel spot you need to split your flow down to nano and break out the alligator clips and get to work. (If you don't know what I'm talking about, believe me that you are fortunate. There was a time not that long ago where 1 scan per second at 800 resolution was a big deal.)

Okay -- where are we today? 40+ scans per second is possible with 8,000 resolution! We have benchtop FTICR systems that are more sensitive than triple quads when operated with sensitivity in mind.

DO WE STILL NEED NANOLC?!?  It is 2018. Can the mass spec and good chromatography at realistic flow rates be a success for proteomics?  Maybe I'm just optimistic because I've hated nanoLC from the first time I ever heard of it, but I think it really is time. For further evidence:

Check this out -- these authors use a great term in this awesome new paper in press at ACS -- is the NanoLC "dogma?"

This study is AMAZING. Well written, logical, unconventional, and someone in this group is a real chromatographer. This isn't written by a pretend protein chromatographer (like me). They think about confronting this problem from where they should -- from plates to peak dispersion -- working their way through different materials and conditions to get to -- something really really impressive.

The authors didn't reveal their final results in the abstract so out of respect for an awesome piece of work -- I'm not going to give them away here either.  Let's just say that if you are sitting there changing pump seals and dreaming of tossing that nanoLC off the roof of your parking garage -- this might just give you that final bit of motivation to up and do it. There is a reasonable chance that you aren't getting results with that headache that are as good as this team is getting without it.

I feel like I owe the authors of this paper something after reading this. This totally made my day.

1 comment:

  1. Nice paper. It is very easy to get the best of both worlds here using your nano system though. Simply run higher ID capillaries (100um) and different beads (3um Dr. M - 25cm length, or sub 2um core shell - 15cm length). These types of columns are incredibly easy to prepare, and give great performance in sub-2-hour analyses. At a flow rate of 400nL/min with heating to 45-50C, your backpressure will sit around 200 - 250 bar. If your nanoLC doesn't last for months (or years) without a repair at these pressures, you are doing something wrong!