Hello,
I am in the process of making mobile phases for my HPLC research and I had one question about buffer. The way I prepared my 0.1M acetate buffer was as follows.
For the acetic acid I used the c1v1=c2v2 formula. Our stock solution has a concentration of 17.4M and using 0.1M as C2 and 1L as V2. I calculated to find 5.74ml.
For sodium acetate,
I made a solution of 8.20g/l. I used c=n/v. to find the number of moles, I multiplied C*Mm*1L where C is 0.1M and Molar mass of anhydrous sodium acetate is 82.03.
After I made this two separate solutions, I mixed them together until I got the desired PH of 4.5. Would this be a correct way of making this particular buffer? If not please explain, the best way of making this buffer. Thank you!
Hi there,
yes adding base conjugate solution to the acid solution (or the other way around), both a the same concentration, is an easy way to obtain the right pH and the right buffer concentration. Using Henderson Hasselbach equation (pH=pKa + log(base/acid)) you may anticipate the composition of the mix for whatever pH. For instance, If you mix equal volumes of acid and base you would get pH=pKa. For acetic acid, pKa is around 4.75 so to get 4.5 final pH the ratio base/acid = 10(pH-pKa)= 10-0.25= 0.562 which means the volume of base solution has to be 56.2% of the acid solution. This is theory but it gives you an idea about the proportion between the 2 solutions.
Hi there,
yes adding base conjugate solution to the acid solution (or the other way around), both a the same concentration, is an easy way to obtain the right pH and the right buffer concentration. Using Henderson Hasselbach equation (pH=pKa + log(base/acid)) you may anticipate the composition of the mix for whatever pH. For instance, If you mix equal volumes of acid and base you would get pH=pKa. For acetic acid, pKa is around 4.75 so to get 4.5 final pH the ratio base/acid = 10(pH-pKa)= 10-0.25= 0.562 which means the volume of base solution has to be 56.2% of the acid solution. This is theory but it gives you an idea about the proportion between the 2 solutions.
I have a question please,
when i can use the acetate buffer PH 4.5 as a dissolution media for in vitro drug release testing? for which drugs?
Acetate Buffer (0.1 M, pH 5.0) recipe and preparation
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