Fluoride Standard Solution (10 ppm F)

Fluoride Standard Solution (10 ppm F) Dissolve in water R sodium fluoride R previously dried at 300  °C for 12 h, equivalent to 0.442 g of NaF, and dilute to 1000.0 ml with the same solvent (1  ml  =  0.2  mg  F). Store in a polyethylene container. Immediately before use, dilute the solution to 20 times its volume with water R.