Paragraph 7 PROCEDURE

Weigh to the nearest 0.001 g, 2.5 g of the prepared sample and transfer to a 250 ml graduated flask (5.1). Add a little of Petermann’s solution (4) at 20°C, shake very hard in order to stop the formation of lumps and to prevent any of the sample adhering to the side of the flask. Make up to the mark with Petermann’s solution and close the flask with a rubber stopper.

• Shake for two hours on the rotary shaker (5.2). Filter immediately through a dry fluted filter into a dry container, discarding the first portion of the filtrate.

Determine the phoshorus using Method 10 on an aliquot portion of the clear filtrate.