If you have the budget, the Pharmafluidics columns may be an option?
My alternative is to not use the picofrit columns.
Instead I have in the past made a blunt ended column plugged with a self-made
sol-gel frit and mate that to a stainless steel PepSep emitter and take a bit
of a hit on peak resolution. I prefer to use a Sutter laser puller, then pull
tips and pack them. It is important that the packing goes all the way to the
very tip of column with no dead space between the packed bed and the tip; and
to run a standard digest such as a HeLa, yeast or E. coli to QC each column.
If either of these steps fail then pack another one. I have found that a
column with a small gap from the end of the packed bed to the tip results in
inferior chromatographic peak shape and clogs more quickly compared to a column
with the packed bed all the way to the tip which is more robust and long lived.
At first, it may (will) take some time and a few (or a lot of) failures to pull
a good tip and also pack a good column but with concerted patient effort it
becomes fairly routine. I favor a Sutter laser program which produces a
fairly short tip that after separation has a very fine point, too fine, and
then I very very gently with almost no pressure drag it briefly across 2000
grit lapping paper to knock off the really fine part of the tip. This results
in a reproducible tip opening ~10µ which packs very nicely ... most of the time
... as long as the bed doesn't "keystone" before hitting the tip opening. I
use 80% isopropanol:20% acetonitrile as the packing solvent and use an Accela
600 pump to pack at ~500bar. I don't have any success using Helium and a
stirred cell for packing. Those I've packed with gas seem to unpack as the
pressure comes to atmosphere no matter how long I let it depressurize.
Yes, it's tedious and failure rate can be high until you get the hang of it. I
would like to find a way to fabricate a frit into a pulled tip, but so far
haven't had success with that.
Best,
Brian
Brian Hampton
Proteomics Core Lab
Center for Vascular and Inflammatory Diseases
University of Maryland School of Medicine
BioPark One, Rm 301
800 West Baltimore Street
Baltimore, MD 21201
410-706-8207
On 7/21/20, 9:57 AM, "ABRF Discussion Forum on behalf of Robert.Salzler"
<email obscured> on behalf of <email obscured>> wrote:
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HI,
Many of us who use New Objective emitters are experiencing similar supply
issues. I have used their emitters exclusively for a number of years.
My last order was this past spring. I am down to my last 20 emitters- and
have no idea what to do when I run out. We have run 1000's of patient samples
with this set up on multiple MS insturments.
After countless time of trying to reach New Objective- I finally have a
ship date of October 20th. We have not been able to shut down due to COVID,
and our MS core needs to continue to run.
So I feel Turck's pain.
Robert R. Salzler
Regeneron Pharmaceuticals, Inc.
Therapeutic Proteins
Bioanalytical & Biomarker Technologies
Building 10, Room 162
777 Old Saw Mill River Road
Tarrytown, NY 10591-06707
Office: 914-847-3075
Cell: 716-864-6787
On 7/21/20, 9:45 AM, "ABRF Discussion Forum on behalf of turck"
<email obscured> on behalf of <email obscured>> wrote:
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_________________________________________________________________
Dear MassSpecers, we have been using PicoFrit Self-Pack Column: 360
μm OD 75 (article no: PF360-75-10-N-5) that we pack ourselves. Our last
order for the columns was placed in March and we still have not received them.
Can anybody recommend a similar product from a different vendor that is
available? Thanks much! Chris
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