User:Matt Hartings/Notebook/AU Biomaterials Design Lab/2014/02/10
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There was a ppt formed after storing the ethanol/ZnS QD solution at -20 over the weekend. I centrifuged this mixture at 4000rpm for 15 minutes. I resuspended the mixture in 5 ml of water (per tube) and added 40mL of ethanol and placed the solution back into the freezer. It seemed that the precipitate took 2-3 hours to fully form. I centrifuged these samples. I suspended all of the samples in 10mL of water and collected all of them in a single vial. I added 40mL of ethanol and placed at -20C for 2 hours. I centrifuged the sample, placed the supernatant in the waste and put the sample on the lyophilizer to dry over night.
synthesis I followed the previous procedure. Again, it took about 1.5mL of the NaOH to get to a pH of 11 (as measured by pH strips). This time, though, I noticed the formation of a black ppt as I walked the sample over to put it on the schlenk line. This persisted until I added the Na2S at which point the solution was a clear/pale orange color. After the synthesis was completed, I removed the stir bar and added 150mL of ethanol and let a ppt form at -20 overnight.
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