I tried making stock solution of 100 mg/ml of Ampicillin from anhydrous Ampicillin from Alfa Aesar. I mixed Nuclease free water to 5 g of anhydrous Amp to make it 50 ml. However, it wasn't dissolved properly. I tried stirring with magnetic beads and water bath warming but it didn't work. I couldn't pass it through the 0.2 ul or 0.8 ul syringe filter. I was suggested to add few drops of 1M NaOH or 1M NH4OH. But, i had to add quite a lot to make it a bit better. I am worried about the final concentration of Ampicillin now after adding so much 1M NaOH. Am i missing something here?
Sodium ampicillin is fairly soluble in water and should be fine at that concentration. However ampicillin trihydrate or ampicillin anhydrous is much much less soluble, I think the limits are around 5-10 mg /ml. I'm guessing you are not using the sodium salt so yes if you want that concentrated of a stock solution you need to add NaOH. You could make a less concentrated stock solution or you could just get some sodium salt.
Ampicillin is (slightly) soluble in water, you should be able to achieve 100 mg/ml, thats what our lab used for stocks, however Sigma here: https://www.sigmaaldrich.com/content/dam/sigma-aldrich/docs/Sigma/Product_Information_Sheet/a9393pis.pdf is recommending a 50 mg/ml solution in water, so try that. If that doesn't work, I would source a new ampicillin supply.
Best of luck!
Sodium ampicillin is fairly soluble in water and should be fine at that concentration. However ampicillin trihydrate or ampicillin anhydrous is much much less soluble, I think the limits are around 5-10 mg /ml. I'm guessing you are not using the sodium salt so yes if you want that concentrated of a stock solution you need to add NaOH. You could make a less concentrated stock solution or you could just get some sodium salt.
To get past 100mM of anhydrous ampicillin dissolved you would need to lower the pH to ~3.44 in 70:30 EtOH:H2O. You could also reach approximately 76 mM using a 50:50 EtOH:H2O at pH ~7.5.
As Michael said, Ampicillin sodium salt is quite soluble in water, yet Ampicillin Anhydrous is not. I would recommend using the sodium salt version if you can, as it will make your life quite a bit easier. I have made an Ampicillin Anhydrous Stock Solution, and it required adding a fair bit of 1 M HCl acid to dissolve. In addition to being more difficult to prepare, I also found that the Anhydrous version tended to not be as stable as the sodium salt version.
Hi, Sulav Shrestha
In response to your question, If you check the webpage of your product you will find at the first page of it (https://www.alfa.com/pt/catalog/J60977/) that your product is soluble to the amount they recommend in an 1M NH4OH solution (then you can solubilize it to 50mg/mL). I don't thing it will disturb your culture because it will be well diluted when applied.
Other option is to get in touch with its technical support (https://www.alfa.com/pt/catalog/tech-inquire/J60977/) and ask them about your question because they need to have responsibility for what they sell. Don't you think?
Hope it helps.
Thank you everyone for your suggestions. I got it worked with Ampicillin Na, its reasonably soluble in water. Before i was using anhydrous Ampicillin, therefore, i guess i was having trouble.
- Badges
- Science topic
- Similar topics
- Biological Science
- Molecular Biology
- Biomolecules
- Nucleic Acids
- DNA