Molecular Probes AlignFlow beads, cat # A-7305 (5 responses). I pulled out
the catalog, and sure enough there's a 6 micron bead (A-7305) and a 2.5
micron bead (A-7304) both offered "for UV excitation". No info on CV, but
they're marketed specifically for cytometer setup. There are also
"DAPI-Like flow cytometry reference beads" offered in the same sizes
(F-7310 and F-7311), but with slightly weaker and more variable signal
meant to simulate DAPI stained cells. Anyone lacking contact info, try
www.probes.com.
Next most frequent (3 responses) were Polysciences BB beads. Their Cat
#18340 was said to give good blue fluor (CV's approx 1.0) with UV
excitation. Other Polysciences suggestions included a small (0.5um) bead
with Ex(max) 365nm and Em(max) 468nm. Used as calibration for bacteria,
but said to have a good strong signal. CV's well under 2.0 on a Facstar
Plus and stable for at least a year for one user. Cat #23520. Bigger
beads, apparently with same fluor, are Cat #19102 and Cat #19103. Contacts
are: (email) polysci@tigger.jvnc.net, (www) http://www.polysciences.com.
Three respondents prefer to stick with a biological standard, i.e. chick
or trout erythrocytes or calf thymocyte nuclei, stained appropriately. One
product is BDIS DNA QC kit (try via www.bdis.com, though I couldn't get
through today, or contact tom_frey@bdis.com). Partec (via Cytomation,
their U.S. distributor, www.cytomation.com or matto@cytomation.com) offers
fixed stained (good for UV) trout cells (CV <= 1% and stable "long term"
at room temp) and unfixed unstained thymocyte nuclei. Another user just
fixes CRBC in glutaraldehyde and adds Hoechst dye for a homebrew
reference.
Two other suggestions were Coulter Immunobright beads, and multispectral
beads from Spherotech (contact via email at jwsphero@aol.com).
Thanks again for the help!
Robert L. Becker, Jr.
Col, USAF, MC
Department of Cellular Pathology
Armed Forces Institute of Pathology
Washington, DC 20306-6000
202-782-1573