19 January 2018 (Friday) - Stain Comparison



I was asked to help with the evaluation of the new departmental automated slidemaker-stainer. I was to compare slides made on the old device with those made on the new one. Ideally there shouldn’t have been much difference.

There was. The new device gave much paler stain. I wondered why.

My first thought was the buffer. I got out the pH meter. Despite having followed the instructions in preparing the buffer, the stuff had a pH of 7.10. I made up fresh using measured amounts of buffer and water and got some with a pH of 6.83. that was better.
However the stain was still pale.
I looked at the stain times programmed into the devices. 

 
The new one had shorter staining times. That’s why it gives a paler result.

I can’t help but wonder why the two machines have different staining times though?

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