User:Matt Hartings/Notebook/AU Biomaterials Design Lab/2014/02/10

Biomaterials Design Lab

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Objective To synthesize more Mn-doped ZnS QDs using the protocol described here and to continue purification of the QDs that I synthesized Thursday. Description Add experimental record here. Include what, how, and why... Data precipitation 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. Notes This area is for any observations or conclusions that you would like to note. Use categories like tags. Change the "Course" category to the one corresponding to your course. The "Miscellaneous" tag can be used for particular experiments, as instructed by your professor. Please be sure to change or delete this tag as required so that the categories remain well organized.