Usually reproducibility is a huge problem in nanoLC MS
using an conventional 2-column setup utilizing sub-2µm solid core particles.
Due to the high pressure that is applied to achieve
best efficiency, mechanical parts have reduced life time, undergo faster
service intervals and obtain performance variation (pressure fluctuation).These
phenomena led to an fluctuation of retention times and resolution from run to
run.
Although nanoSpray displays better sensitivity
researchers have been going back to microflow application because it offers a
good comprise because sensitivity and reproducibility.
The new Evosep one nanoLC introduced a few concepts, which
are going to overcome these limitations. The system has 4 low pressure pumps and a single high pressure pump linked by the sample loop.
The Evosep one pre-forms a gradient
at low pressure and high flow and stores it within an sample loop. While
sitting together with sample no mixing occurs.
Before loading into the sample loop the sample is
cleaned up with an zip-tip like tip, also at low pressure. Since the loop is
directly located behind the tip hydrophilic peptides won’t get lost and will be
transferred entirely to the analytical column.
Since the gradient is pre-mixed only a single pump is
required for eluent delivery. This is way better for reproducibility than two
separately working pumps for each of the mobile phases.
Further, this unique system provides less carry over
and an optimized duty cycle with less overhead time (-35% time saving compared
to EASY1200 nano).
All in all this system provides great features and I
am pretty sure it will become the method of choice for short gradient clinical proteomics.
Source: https://www.biorxiv.org/content/biorxiv/early/2018/05/15/323048.full.pdf
The company evosep has got a pretty cool homepage and a youtube channel, which definitely should be checked out.
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