AW: [Histonet] Formaldehyde concentration measurement

[Rene J Buesa]

Gudrun:
Please check the posting by Tony Henwood using PAS reagent. Fisher sells Schiff reagent specific for formaldehyde detection (Cat. No.23-245687).
The posted method by Tony Henwood will give you an idea but is not quantitative. If you want to quantify you will have to test different known concentrations.
You could start with "pure" methanal (the  "famous" 37% solution, making sure of the concentration as stated in the label.
That will be your solution "A"; dilute it with deionized water in half = solution "B", and so on until you get to a dilution of ca. 0.6% after 6 consecutive dilutions.
Try all of them with the method posted by Tony Henwood and prepare an absorption curve in a photocolorimeter with a "red" filter (lambda 620-720 nm) using the lambda that gives you maximum absorption.
Construct an absorption curve (% absorption in the "Y axis" and "% formaldehyde" in the "X axis" (since the % in Y will depend on the % concentration in X).
Any other sample could be treated with the procedure, read at the same lambda and you can find the % concentration in the graph. This value will be as inaccurate as the variation in the initial concentration.
Rene J. 

Gudrun Lang <gu.lang <@t> gmx.at> wrote:
We use 8% Formaldehyd. 
What would be the right amounts of reagents to test this concentration?
Can you help?

Gudrun Lang



-----Ursprüngliche Nachricht-----
Von: histonet-bounces <@t> lists.utsouthwestern.edu
[mailto:histonet-bounces <@t> lists.utsouthwestern.edu] Im Auftrag von Tony
Henwood
Gesendet: Freitag, 21. Oktober 2005 00:14
An: Maray Weirauch; histonet <@t> lists.utsouthwestern.edu
Betreff: RE: [Histonet] Formaldehyde concentration measurement

The following might be of use:

Test for validity of formalin concentrations


Principle:

The Schiff's reagent (PAS stain) is used to detect aldehydes and In this
technique it is used to titrate a solution of formalin The concentration of
which is unknown.


Solutions:

1. 1 ml of formalin fixative to be tested.
2. 5 ml of 2.4% aqueous sodium bisulphite - prepare fresh.
3. Schiffs reagent.


Procedure:

1. Add 1 ml of formalin to 5 ml of sodium bisulphite.
2. Mix and allow to react for 15 minutes at room temperature stirring
from time to time.
3. Add 100µl of Schiff reagent.


Results:

If solution turns a deep violet than initial concentration of formalin is in
excess of 4% (i.e. 1.6% formaldehyde).


Reference:

Jaspers, B., J. Histotechnol (1987) 10 (4): 263-265.



Regards

Tony Henwood JP, MSc, BAppSc, GradDipSysAnalys, CT(ASC)
Laboratory Manager & Senior Scientist
The Children's Hospital at Westmead,
Locked Bag 4001, Westmead, 2145, AUSTRALIA.
Tel: 612 9845 3306
Fax: 612 9845 3318




-----Original Message-----
From: histonet-bounces <@t> lists.utsouthwestern.edu
[mailto:histonet-bounces <@t> lists.utsouthwestern.edu] On Behalf Of Maray
Weirauch
Sent: Friday, 21 October 2005 5:17 AM
To: histonet <@t> lists.utsouthwestern.edu
Subject: [Histonet] Formaldehyde concentration measurement


Hi Histonetters,
Does anyone know of a simple, inexpensive way to measure the formaldehyde
concentration in a prepared, buffered formalin fixative? Thanks! Maray

_______________________________________________
Histonet mailing list
Histonet <@t> lists.utsouthwestern.edu
http://lists.utsouthwestern.edu/mailman/listinfo/histonet

**********************************************************************
This email and any files transmitted with it are confidential and intended
solely for the use of the individual or entity to whom they are addressed.
If you are not the intended recipient, please delete it and notify the
sender.

Views expressed in this message and any attachments are those of the
individual sender, and are not necessarily the views of The Children's
Hospital at Westmead

This note also confirms that this email message has been
virus scanned and although no computer viruses were detected, the Childrens
Hospital at Westmead accepts no liability for any consequential damage
resulting from email containing computer viruses.
**********************************************************************


_______________________________________________
Histonet mailing list
Histonet <@t> lists.utsouthwestern.edu
http://lists.utsouthwestern.edu/mailman/listinfo/histonet


_______________________________________________
Histonet mailing list
Histonet <@t> lists.utsouthwestern.edu
http://lists.utsouthwestern.edu/mailman/listinfo/histonet



		
---------------------------------
 Yahoo! FareChase - Search multiple travel sites in one click.