I am designing a growth medium at pH 3,5 for a Lactic acid bacteria. But I don't know what buffer to use.
*I tried to use sodium.acetate/acetic.acid but my microorganism is inhibited by this compound at very low concentration.
*I understand that DIPSO buffer has pKa=4.0-5.5 but don't know why: It's only used to buffer between pH 7.0-8.2.
Thanks Fadhil. But the microorganism that I'm cultivating, presents inhibitions at very low concentrations of some of that compounds. I'll try to look for more buffers in your recomended ref.
Mark: It depends in whether you want to study the effects of lactate or pH.
You may possibly consider saturated aqueous solution of potassium bitartrate (KHC4H4O6), which is a NIST's primary pH buffer standard with pH 3.557 at 25 °C, thus seemingly close enough to required value (3.5). In aqueous solution, potassium bitartrate dissociates to acid tartrate, tartrate, and potassium cation. Potassium bitartrate is also named potassium hydrogen tartrate.
An alternative pH buffer for pH 3.5 is the phosphate buffer that can be obtained by dissolving 68.0 g of potassium dihydrogen phosphate with water to obtain 1000.0 ml of aqueous solution. The pH is adjusted to 3.5 with phosphoric acid (cf. European Pharmacopeia, section 4.1.3: ‘Buffer Solutions’, 2005, p. 430).
Just to add this information: cf. also RG-Thread:
Does anyone know a buffer solution with pH range ( 1 to 5 ) ? (2015-03-06)
https://www.researchgate.net/post/Does_anyone_know_a_buffer_solution_with_pH_range_1_to_5
Regards, W. M.
- Badges
- Science method