Re: LSC Standards

[alanjack@umich.edu]

John Harvey/Radsafe at large,

I strongly suggest that you prepare the solutions yourself.  I have
found significant differences in the calibrations obtained with the
commercial sets and mine.  The reasons for the differences include:
different volume of fluid, lack of water  (or other solvents in the
solution), different LSC fluid (especially the non-tolulene based
fluids), different vials, etc.

Eliminate these uncertainties-make your own standards.  Since I enjoy
the services of a master glassblower, I prepared a sealed version of my
standards.  I used NIST standards (tritiated water and C-14 labeled
hexadecane).  The standards were filled with an argon atmosphere to
minimize chemical reactions.  These standards compared well in blind
testing.  These standards have also stored well and thereby saved me
some lab prep time.

-Alan Jackson alanjack@umich.edu
University of Michigan-Radiation Safety

>   Try C-14 labeled toluene quenched with (non-radioactive)
>   acetone.
>   
>   Wes Van Pelt
>   vanpelt@ios.com
>   
>   ----------
>   From: 	John Harvey[SMTP:harveyj@mcmail.CIS.McMaster.CA]
>   Sent: 	Tuesday, April 16, 1996 4:01 PM
>   To: 	Multiple recipients of list
>   Subject: 	LS Standards
>   
>   Once again I seek your collective advice.
>   I wish to purchase H-3 and C-14 standard solutions to
>   make up a set of  quenched standards. My experience is
>   that a sodium carbonate and  formaldehyde standard
>   solution is nothing but trouble.
>   
>   It would be greatly appreciated if you could let me know
>   of your  experiences with standard solutions from the
>   commercial companies. (I  doubt if we could afford a
>   solution from NIST.) Please send your comments  directly
>   to me--if you have strong opinions as I do, this could
>   save you  from a libel suit.
>   
>   Thanking you in advance
>   John
>   ==========================================================
>   ============= John Harvey                            |
>   McMaster University Senior Health Physicist
>   | NRB-110
>   (905) 525-9140 ext 24226               | 1280 Main St.
>   W. harveyj@mcmail.cis.mcmaster.ca         | Hamilton,
>   Ont Canada L8S 4K1