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October 2009

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Subject:
From:
"Tsuchiya, Masakazu" <[log in to unmask]>
Reply To:
The Pharmaceutical Microbiology Forum Email List <[log in to unmask]>
Date:
Wed, 14 Oct 2009 17:31:10 -0400
Content-Type:
text/plain
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text/plain (105 lines)
Dear Mohammed Yousffi,

I just calculated the amount of possible endotoxin in your sample.
The amount of 18 ppb is 18 ng/mL of total carbon.  Assuming endotoxin is
about 10% weight of the total carbon, the concentration of endotoxin in
your sample is 1.8 ng/mL.  The potency of purified endotoxin is about
5-10 EU/ng, but in this case, endotoxin is naturally occurred endotoxin.
Assuming the potency of the endotoxin is 1 EU/ng, the endotoxin activity
in your sample can be 1.8 EU/mL.  So it was possible that you observed
0.65 EU/mL endotoxin in a water sample with 18 ppb TOC.

I know it is too much assumption, but if the sample contains mostly
endotoxin, endotoxin can be detected in a sample that shows under the
detection limit of TOC.  The LAL test detects ppt order of endotoxin.

I am sorry for not providing any useful information to solve your
problem.
It is just for your information.

Best regards,

KAZ Tsuchiya
Masakazu Tsuchiya, Ph. D.
Senior Research Scientist
Endotoxin and Microbial Detection
Charles River
TEL: 843-766-7575
FAX: 843-766-7576
E-mail: [log in to unmask]
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-----Original Message-----
From: The Pharmaceutical Microbiology Forum Email List
[mailto:[log in to unmask]] On Behalf Of Mohammad Yousffi
Sent: Thursday, October 08, 2009 10:47 AM
To: [log in to unmask]
Subject: [PMFLIST] Endotoxin In RO system but TOC is low

Can someone explain to me why you would see high Endotoxin (0.65 Eu/mL)
in a USP purified RO water system (With RO membranes and an EDI system)
when the TOC is low (~ 18 ppb)?

We installed new membranes as part of our Preventative maintenance and
initially we saw high TOC (>300 ppb) and then it dropped after draining
the storage tank. Now its in normal range but we see high Endotoxin in
the water.

Thanks in advance!
--
Mohammed Yousffi
[log in to unmask] 

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