The sodium bicarbonate coated tube filter method provides a means of separating and collecting atmospheric gaseous fluoride and particulate fluoride samples.

Since the samples are collected on the dry tube and filter, the fluoride may be eluted with a small volume of eluant (see Section 10 for specific instructions on fluoride elution). Elution into a small volume and the sensitivity of the analytical methods employed allow the analysis of the collected fluoride to fractional parts of a microgram per cubic metre on samples taken for a 12-h period.

1.1 The sodium bicarbonate-coated glass tube and membrane filter method provides a means for the separation and collection of gaseous atmospheric forms of fluoride reactive with sodium bicarbonate and particulate forms of fluoride which are collected by a filter. The test method is applicable to 12-h sampling periods, collecting 1 to 500 g of gaseous fluoride at a 15 L/min [0.5 ft³/min] sampling rate or about 0.1 to 50 g/m ³. The length of the sampling period can therefore be adjusted so that the amount of fluoride collected will fall within this range. The actual lower limit of the test method will depend upon the sensitivity of the analytical method employed and the quality of reagents used in tube preparation and analysis. It is recommended that the lower limit of detection should be considered as two times the standard deviation of the monthly arithmetic mean blank value. Any values greater than the blank by less than this amount should be reported as "blank value."

1.2 The values stated in SI units are to be regarded as standard. The inch-pound units in brackets may be approximate.

This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.