I am attempting to replicate a HPLC method for the determination of water-soluble vitamins and the mobile phase consists of 0.1M Phosphate buffer (pH 7).
The paper states that they made up the buffer by "the addition of 0.1 mol/L potassium dihydrogen phosphate and 0.1 mol/L potassium hydroxide"
However, I would usually make up this buffer by adding potassium phosphate dibasic and potassium phosphate monobasic (in the correct quantities) to water.
Are these two methods the same and would the resultant buffer be the same?
Thank you!
Dear Thomas Booth
Both buffers are different. As per the paper you have mention the potassium hydroxide has different function in the mobile phase.
Further the RT of the contents you need to evaluate can be achieved from many buffer compositions but there will be some difference in the baseline and the chromatogram patterns, also there will be variation in the Tailing factor & the plate counts.
But my suggestion is to plan the analysis on the both method such that there will be clear idea of the equivalency between the two or three methods which you want to follow and then it will give you the clear idea about the impact after the comparative studies of these methods.
You may want to check this related RG query:
https://www.researchgate.net/post/Why_do_I_struggle_to_adjust_lower_pH_of_my_phosphate_buffer_at_a_certain_pH_point_even_though_I_add_too_much_acidic_solution
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