Diatom Digestion - Acidity Problem on Slide


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Diatom Digestion - Acidity Problem on Slide

Post by casbiostudent » Thu Mar 10, 2011 9:55 am


at the moment I'm producing diatom slides during my work placement.
The digestion process starts with the adding of HCL (get rid of salts and iron) then a wash in the centrifuge.
Then sulphuric acid is added to get rid of organic matter, potassium permangante is added and the solution is then cleared with oxalic acid.
Now the cleared solution is washed 5 times with deionised water.
After that with asterile pipette the solution is diluted and transferred on to cover slips.
They are then drying off over night.

The cover slips often show acidic white rings, which deteriorate the quality of the slide and make it harder to count.

Does anyone have experience with those acidity problems on produced diatom slides?
Is there anything you can do to avoid them?
Less chemicals?, less saturated oxalic acid?, more washes? (trial run till 8 was done no pH change seen), longer dryion off period?, slower drying?

Thanks for replies.

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