Question

Pyridine is basic and can be used as a buffer. Why is pyridine rarely used as an HPLC buffer?

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Answer 1

Buffer solution:

Buffer solution is made by the addition of acid and base solution. A buffer must consist of a weak conjugate acid-base pair, meaning either a. a weak acid and its conjugate base, or b. a weak base and its conjugate acid.The of this solution is remain unchanged by adding acid or base.   In general the of this solution is constant.

The Pyridine which is a weak base ; C₅H₅N) and with the pyridinium cation (C₅H₅NH⁺), such as Pyridinium Chloride its conjugate acid, form buffer.

For best buffer which can be used as an HPLC buffer , is that which has a pH at least 2 units away from the pKa but the pH range for pyridine buffer is 4.9 to 5.9 while the value of Pka for pyridine is 5.,23.

Hence the pyridine rarely used as an HPLC buffer