we have faced a similar problem on our 420A/H not only with the test
peptide but also with other proteins like beta-lac (AB sequencing
standard), HSA (HP sequencing standard) and own proteins and peptides. The
compositional errors are acceptable but the absolute recoveries vary
between +/- 20% over 3 to 5 analysis of the same sample. So far we have
replaceed everything, the solvents and chemicals, the slides and all valve
blocks and tubings (some of them are new some others are from a retired
420). Nothing helped, compositions were always good but the variabilities
in mass recovery remained. So far, the AA standard reproducability was
good, indicating that the derivatization works fine and that the problem
may be somehow connected with the recoveries after hydrolysis.
Any other 420 A/H user with similar experience?
many regards
Peter
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Dr. Peter Hunziker | E-Mail: phunzi@bioc.unizh.ch
Universitaet Zuerich |
Biochemisches Institut | Tel: +41-1-635 55 20
Winterthurerstr. 190 | Fax: +41-1-635 68 05
CH-8057 Zuerich, Switzerland |
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Visit our department homepage: http://www.unizh.ch/biochem
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