no PharRed

From: Claude Cantin (cantinc@uhnres.utoronto.ca)
Date: Wed May 23 2001 - 17:06:55 EST


Hi All

I have been unable to detect a PharRed signal from samples I have been
given, and don't know if the problem is instrument or labeling error.

MoFlo set up is as follows:


     Hammatsu 957-08 PMT all around

     Omega Optical Filter Set XF501  (consists of 710 DRLP,
     670DF40, and 740EFLP)

     Melles Griot 35mW HeNe


Red laser alignment seems fine:  "Molecular Probes AlignPlus beads for
633" are almost off scale if no ND filter, at 399V, linear gain 1.  BD's
APC like Calibrites show excellent separation + / - ( >2 logs) 580V.
Whether I measure APC in FL5 (remove 710LP dichroic, use 670/40BP) or
FL6 (710LP plus 670BP), I obtain good APC signal.  But no PharRed with
the 710LP dichroic / 740EFLP in FL5, and no PharRed signal even if I
remove the 710LP dichroic.

BD Pharmingen Technical data sheet recommends a Hammatsu R3896 PMT for
improved red sensitivity.  Is the Hammatsu 957-08 deficient in the >740
range?

If not, what's up?

Thanks,

Claude











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