[ Reagent Questions ]

Dear FLOWers,
  I am here again with some very basic questions on flow cytometry reagents. I am sure
all of you will be extending your helping hands. This is an area all of you will be
familiar.
  We have a FACS Calibur with 2 lasers and use 4-colour reagents.
  FL-1		      FITC
  FL-2		      PE
  FL-3		      PE-Cy5
  FL-4		      APC
  1.	     We buy single colour reagents from B-D and use them in the combination
needed.
  We have repeatedly observed that even if you buy all the 4 labels at the same time
having the same expiry date (the manufacturing date of course is not known), the PE and
its tandem dyes lose the fluorescent intensity and become non-functional within 6 months,
well ahead of the expiry dates. We have stored the reagents properly, at 2-8°C, in dark,
in a sterile manner etc.
  Of course, it is not known how old the stock is, when received. That is a totally
different issue. But if the property of PE losing intensity is well known, is there any
way of making its life longer?? I know that freezing should not be done!!
  2.		      Are there any other dyes which can be used in the place of PE for
FL-2 in FACS Calibur, which are cost effective and have longer shelf life?
  3.		      B-D usually supplies 2 ml of reagent, which is difficult to exhaust
during its short shelf life of ~3 months!! Is there any other company supplying smaller
lots or lyophilized product?
  4.		      Finally, can you please share your experience with reagents from
other manufacturers, if you do not mind?
  I request all the experts and gurus in this field to respond.
  A. Raja     

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