Dear Colleagues,
I am are preparing a 0.15 mm -i.d. capillary column
packed with LiChrospher(Merck) RP-18 (0.012 mm), this
matrix in n-propanol (40 mg / 200 uL) was sonicated for
15 min, the capillary column was filled with 150 uL of
the prepared matrix and packed until 5000 psi. I use
human insulin as a standard, running TFA 0.1% and
acetonitrile as mobile phase at 3 uL/min but the
retention time for such protein is too high. I have
also tried Poros R2, but this matrix gave me a very
high back pressure (over 5000 PSI at 1uL/min). Since I
found a few references using this matrix, I wonder what
am I doing wrong.
Does anyone have an idea of what could be wrong?
Would Poros R1 work better than R2?
What solid phase you suggest ?
Any advice in capillary LC-MS technique will be very
helpful .
Thanks in advance.
Elvio Botelho
Brazilian Center for Protein Research and Services-CBSP
Laboratory of Protein Chemistry and Biochemistry
University of Brasilia
Brasilia - DF Brazil
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