I need to prepare some phosphate buffer solutions (pH 5, 6, and 7) for ion exchange chromatography. However, its working pH range is 5.8-8.
Can I possibly prepare phosphate buffer solution at pH below its range(
A simple phosphate buffer is used ubiquitously in biological experiments, as it can be adapted to a variety of pH levels, including isotonic. This wide range is due to phosphoric acid having 3 dissociation constants, (known in chemistry as a tricrotic acid) allowing for the formulation of buffers near each of the pH levels of 2.15, 6.86, or 12.32. Phosphate buffer is highly water-soluble and has a high buffering capacity, but will inhibit enzymatic activity and precipitates in ethanol. The buffer is one of the most popular currently used and is commonly employed in molecular and cell biology, chemistry, and material science, among many others.
Dear Neva
you can certainly change the pH of phospate buffer by adding and acid. I think that phosphoric acid or MES is preferable respect HCL that contain cl- ions and may affect your results in case you are performing anionic exchange.
However the buffering capability of phosphate outside the ph range 6-7.8 is very low therefore i suggest to you to use Trisma-base at pH=8 (you can use MES to reduce the pH instead phospate) and MES buffer at pH5.
ciao
Manuele
A simple phosphate buffer is used ubiquitously in biological experiments, as it can be adapted to a variety of pH levels, including isotonic. This wide range is due to phosphoric acid having 3 dissociation constants, (known in chemistry as a tricrotic acid) allowing for the formulation of buffers near each of the pH levels of 2.15, 6.86, or 12.32. Phosphate buffer is highly water-soluble and has a high buffering capacity, but will inhibit enzymatic activity and precipitates in ethanol. The buffer is one of the most popular currently used and is commonly employed in molecular and cell biology, chemistry, and material science, among many others.
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