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Help needed/urgent

David R Gerty rgerty at draper.com
Fri Mar 4 11:26:08 EST 1994

In article <199402220409.UAA01431 at net.bio.net> GOVINDJEE at C.SCS.UIUC.EDU ("GOVINDJEE") writes:
>Subject: Help needed/urgent
>Date: 22 Feb 1994 04:09:17 -0000

>Dear colleagues:
>I would appreciate it very much if someone can provide me with a 
>reference of a simple method in which photosynthesis of a Elodea branch
>is measured by the oxygen bubbles released upon illumination.I need 
>except that the name Winkler method has stuck in my mind. I also 

You would be much better off with a dissolved oxygen electrode.  Almost any 
environmental lab would have one such as a YSI probe.  I used one in a 300 ml 
BOD bottle or an erlynmeyer flask (classroom expt. in 1973) to measure 
respiration of a crab.  You could watch changes 'real-time' with variations in 
light intensity.

The Winkler method (US EPA Methods for Chem. Analysis of Water and Wastes, (my 
copy is 1973)) in a nutshell takes some skill ), 300 ml BOD bottles, sodium 
azide MnOH, KI, sulphuric acid and a titration. Basicly, the Mn(OH)2 reacts 
with O2 to MnO(OH)2 ppt, dissolve with acid, react with KI to I2, titrate. I 
would skip the titration and use a DPD chlorine test kit for drinking water.  

>glassware used ? the Winkler apparatus? Where is it available?
Any lab supply house.
>We can either purchase it or build it with full details. This is needed
>for teaching.

>Professor of Plant Biology
>Fax: 217-244-7246
>Fax#2: 217-337-6196

>Thanks for your help.

DISCLAIMER: I'm not in this business anymore. 

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