Division 4.1 Solution A

Barium borate hydroxide buffer: pH 10,6 ± 0,1 at 20 ^o C.

Dissolve: 25,0 g of barium hydroxide (Ba(OH)2.8H2O) in water and dilute to 500 ml.

Dissolve: 11,0 g of boric acid (H3BO3) in water and dilute to 500 ml.

Warm the two solutions to 50 ^o C and mix.

Shake and cool the mixture to room temperature.

Adjust the pH to 10,6 ± 0,1 with the barium hydroxide solution and filter.

Store the solution in a tightly stoppered container.

Before use, dilute the buffer with an equal quantity of water.