Re:

["Charles Meyer" <CMEYER@brc1.tdh.state.tx.us>]

From:          "Webb, Jim" <jwebb@health.ohio.gov>
   
     Fellow Radsafers
     
     We were reviewing environmental water sample data that was analyzed 
     for Iso U and Iso Pu. It was learned that the sample contained no 
     preservatives and the samples had sat in the laboratory for 15 days 
     before being analyzed.  
     
     We would like to know if you would reject or accept the data. A brief 
     explanation for your answers would be appreciated. 
     
     JWEBB@HEALTH.OHIO.GOV

We too have been wrestling with concern about a " wall effect" -- 
ions in solution plating out on the inner surface of a container.  
Our lab has usually insisted on acidification of the sample with 
nitric acid to a pH of 2.  When pressed the lab indicated that the 
sample could be acidified when brought back to the office, as long as 
it sat for around 48 hours before being tested.   I contacted the EPA 
labs and inquired how samples were handled there, pointing out that 
samples which were acidified with nitric acid could not legally be 
transported by commercial aircraft.  They indicated that they did not 
acidify samples which they took to their lab.  Several questions 
which have arisen out of our experiences are as follows:

1. Does a sample which is to be analyzed for certain metals have to 
be acidified as soon as possible after being taken?

2.  If you can wait until you return to your main office, but still 
have to acidify the sample, how long must it sit before you can rely 
on the ions being returned to solution?

3.  Does the materials of construction of the container, have any 
effect on whether or not ions will plate out?  We use polyethylene 
cubitainers nowadays.

4.  Will insoluble oxides behave like soluble salts and exhibit the " 
wall effect " phenomenon?  Or more to the point does the " wall 
effect" truly exist, and should we be concerned with sample 
acidification for that purpose?

5.  Is there literature on sampling procedures, which give guidance 
on sample prep in the field specifically for radionuclides which take 
chemical reactions into account?  I remember back in the '50's some 
discussion in the literature regarding the " wall effect"  but can 
find nothing about it now. Could I be using the wrong terminology?

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               Russ Meyer                            
               Internet: cmeyer@brc1.tdh.state.tx.us 
               tel: 512/834-6688                                                    
               fax: 512/834-6654
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