Is your reproducibility outside the normal instability of CE? Does your CE
system have column/buffer thermostating? Without some form of
thermostating the reproducibility/stability will not be real good. If you
are looking for stability/reproducibility of HPLC then you are with the
rest of the research world that uses CE. As for the peptides, are any of
them charged (Arg, Lys)?
Regards,
Damon.
At 01:21 PM 2/10/98 +0100, you wrote:
>To all ABRF's,
>
>I am trying to analyse dipeptides and tripeptides
>in low concentrations (<<10 mikrogram/ml) with CE.
>I have a problem with the stability and reproducibility.
>
>I am using an underivatized silica capillary and
>precondition it with NaOH, H2O, H3PO4, H2O and
>50 mM Phosphate buffer pH=2,3.
>Run voltage=15 kVand run temperature=10 C.
>Detection 214 nm.
>
>The peaks in the electropherogram seem to have
>different migration time from one analysis to another.
>Does anyone think that a change in voltage or
>temperature would help to stabilize the method?
>Or can any other parameter be changed to improve
>the resulted electropherograms?
>
>Thanks in andvance!
>
>Maria Thyboll
>Royal Institute of Technology
>email: k93_mtl@k.kth.se
>
>
Damon C. Barbacci
Department of Chemistry
Texas A&M University
College Station, TX 77843-3255
phone: (409) 845-0613
fax: (409) 845-9485