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We have gravimetrically checked both of our Multi Q-Preps for accurate reagent
delivery, tried new lots of Q-Prep reagent, Dulbecco's PBS, paraformaldehyde
and, spedimen collection tubes. We have tested our water, tried bottled water
and, added 2% and 5% fetal bovine serum to the wash. All to no avail.
We are presently using ACD anticoagulated samples. We have tried using EDTA
as well as heparin. The heparinized samples show less of the problem and the
EDTA samples show no problem. However, we are reluctant to switch to EDTA
since sample stability would be cut short.
In Samples resuspended in PBS (i.e. no paraformaldehyde) particles are visible
but the samples do not turn brown. If samples are washed and fixed substituting
sheath for PBS there is no discoloration but particles are present. Upon
completion of Q-Prep the samples are not particulate and if they are not
washed or fixed they remain a cherry red. Samples lysed with Immuno-Lyse do
not exhibit this problem even though the same PBS and paraformaldehyde are
used.
This appears to be an anticoagulant/reagent interaction. However, we have not
been able to isolate a single reagent.
Any suggestions, comments or just plain condolences would be appreciated.
TIA, klcombs@upj.com
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