Paragraph 3 REAGENTS

Formaldehyde, 25-35% solution, filtered if necessary before use.

Potassium chloride.

Sodium hydroxide, 10 M solution. Care should be taken to ensure that the sodium hydroxide is free from potassium.

Indicator solution: dissolve 0.5 g phenolphthalein in 100 ml 90% ethanol.

EDTA solution: 4 g of the dihydrated disodium salt of ethylenediaminetetraacetic acid (EDTA) per 100 ml. Store this reagent in a plastic container.

STPB solution: dissolve 32.5 g sodium tetraphenylborate in 480 ml of water, add 2 ml of sodium hydroxide solution (3.3) and 20 ml of a magnesium chloride solution (100 g of MgCl₂.6H₂O per litre). Stir for fifteen minutes and filter through a fine, ashless filter. Store this reagent in a plastic container.

Liquid for washing: dilute 20 ml of the STPB solution (3.6) to 1 litre with water.

Hydrochloric acid (ρ = 1.18 g/ml).