A Sensitive Spectrophotometric Assay for the Measurement of Soluble Silica in Water

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> Subject: * * A Sensitive Spectrophotometric Assay

> for the Measurement of Soluble Silica in Water

> Date: Wed, 16 Nov 2005 10:37:07 -0800

>

> A Sensitive Spectrophotometric Assay for the

> Measurement of Soluble Silica

> in Water

>

>

>

> Myrl

>

> Nov 16, 7:30 am

>

> Thanks to Pam Dowd for sending an abstract from 1997

> by Dr. Barbara Manno.

> Before we present the abstract, we'd like to remind

> you that it was Dr.

> Manno, who at the April 2005 FDA Panel Hearings,

> said the following with her

> " tough luck " comment:

>

>

http://www.fda.gov/ohrms/dockets/ac/05/transcripts/2005-4101t3.htm

>

>

> CHAIRMAN CHOTI: Dr. Manno?

>

> DR. MANNO: I wish I had said that. I voted yes

> much based on many of the

> things that Dr. Li commented on, and I think that

> given the testimony here,

> etcetera, from the public and what I heard from the

> public the last time, if

> the doctors and the company provide the information,

> I think we have got

> enough to approve this and that the recipients of

> the device will have a

> choice. And it isn't to have a choice, they can

> make a choice and it's

> tough luck if it doesn't work. (There was a long

> pause here as the audience

> responded audibly to this statement.) No, I don't

> mean that. I would like

> that stricken. No, I believe it will work, I think,

> based on what I have

> seen here and, please, I did not mean that the way

> it sounded.

>

> ----------

>

>

http://www.jatox.com/abstracts/1997/october/manabs.htm

>

>

> Published: Journal of Analytical Toxicology, Volume

> 21, Number 6, October

> 1997, pp. 503-505.

>

> TECHNICAL NOTE: A Sensitive Spectrophotometric Assay

> for the Measurement of

> Soluble Silica in Water Barbara R. Manno, Imad K.

> Abukhalaf, and ph E.

> Manno

>

> The National Committee for Clinical Laboratory

> Standards (NCCLS, 1)

> recommends that Type I water used in clinical

> laboratories must be virtually

> silica (SiO2) free (¾ 0.05 mg/L). The recommendation

> has been adopted by the

> College of American Pathologists (CAP) with the

> inclusion of a question

> regarding soluble silicate in water in CAP

> Laboratory Accreditation Program

> checklists (2). These requirements are based upon

> silica's direct

> interference with spectrophotometric measurements at

> specific wavelengths of

> the light spectrum. Therefore, its presence in water

> not only interferes

> with trace metal and electrolyte analyses but also

> could adversely affect

> many enzymatic determinations such as those

> procedures using alcohol

> dehydrogenase and various phosphatases (1).

>

> A commercial silica testing kit (catalog # 22550-00,

> Hach Silica Test Kit,

> Hach, Loveland, CO) was evaluated. Kit

> specifications indicated that it

> measured silica concentrations in the range of 0-1

> mg/L. Measurement of the

> color intensity of the resulting silicate-molybdate

> complex required visual

> comparison of the developed color to a color disc

> directed toward an

> artificial or natural light source and depended on

> color comparison by the

> naked eye. Hach Silica Testing Kit reagents were

> used in the development of

> a modified procedure for the detection and more

> accurate quantitation of low

> concentrations (¾ 0.05 mg/L) of soluble silica in

> water.

>

> Reproduction of editorial content of this journal is

> prohibited without

> publisher's permission.

>

> This article is available in its entirety by fax for

> $4.00 per page.

> Visa or MasterCard accepted.

> To order electronically click here or call:

> 847-647-2900 ext. 1323 or fax

> request to: 847-647-1155.

>

>

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>

>

http://www.lawyersandjudges.com/contributorinfo.cfm?ContribID=871

>

<http://www.lawyersandjudges.com/contributorinfo.cfm?ContribID=871 & PC=886>

> & PC=886

> Barbara R. Manno, Ph.D. Professor, Louisiana State

> University Health

> Sciences Center in Shreveport, Department of

> Psychiatry, Shreveport, LA.

>

>

>

>