I've extracted PHA in chloroform using soxchlet extraction method at 65 degree celsius and tried precipitating the dissoloved polymer in cold methanol (70%), but could'nt see any precipitation. I've tried this method many times but not able to see the polymer. Is there a problem with my extraction method or the produced polymer is so low in concentration that I'm not able to get the precipitation.
Look at here: https://www.researchgate.net/post/While-extracting-PHB-from-Pseudomonas-I-am-not-getting-precipitate-after-adding-chilled-ethanol-and-acetone-Please-suggest-what-should-I-do
Try without Soxhlet.
I could not extract with cold methanol at 70% either, so I ended up using pure ethanol in a 8: 2 ratio (ethanol: chloroform) and then centrifuged at 4000 rpm for 20 minutes, then remove the supernatant very carefully not to lose the PHB (a small "precipitate" is made at the bottom) and then dried for 1 day at 100°C
I think if you change the ratio of solvents, you can significantly increase the polymer yield. Ethanol is a poor solvent for PHA. Its role is to help chloroform enter the cell. If we take the ratio of chloroform: ethanol 4: 2, the result will be better.
Keep the Ice cold methanol precipitant (with PHA & chloroform) inside the freezer for 10 days. You will be able to observe visible precipitations!
FTIR and RAMAN to get data
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