pH Buffer Solution A buffer solution is an aqueous solution consisting of a mixture of a weak acid and its conjugate base, or conversely. Its pH changes little when a small amount of strong acid or base is added to it. Buffer solutions are used as a means of keeping pH at a nearly constant value in a wide variety of chemical applications. Features and Benefits • pH solution for setting up and calibration of pH probes • 500ml container • pH 4, pH 7 and pH 10 available