OR/14/067 Isolation of cerium phosphate precipitate

Lapworth, D J, Surridge, B, Williams, P J, Heaton, T H E, and Gooddy, D C. 2014. Method for analysing phosphate 18O/16O ratios for waters with high C:P ratios. British Geological Survey Internal Report, OR/14/067.

The cerium precipitants were transferred to 50 ml centrifuge tubes and centrifuged at 3500 rpm for 15 minutes and the supernatant discarded. 20 ml of 0.5 M potassium acetate was then added, shaken vigorously with the sample to resuspend the precipitate and centrifuged at 3500 rpm for 15 minutes and the supernatant discarded. This procedure was repeated twice more to give a total of 5 potassium acetate washes.

• 4 ml of 1 M HNO₃ was then added to each sample tube

This should dissolve all sample ‘gel’ pellets, but some required extra time and extra HNO₃ to fully dissolve.

• 18 ml of ultrapure water added to each sample