APPLICABILITY: The working range is ca. 0.01 to 5 mg/m 3 for a 50-L air sample (see EVALUATION OF METHOD). This
method measures the total concentration of six airborne anions. The corresponding acids may be collected on a single sam pler
and determined simultaneously. Formic acid has been determined by this method [3].
INTERFERENCES: Particulate salts of all the acids will give a positive interference. Chlorine or hypochlorite ion interfere with
chloride determination and bromine interferes with bromide. Silica gel will collect ca. 30% of the free Cl 2 and Br2 in an atmosphere
[4]. Acetate, formate and propionate have elution times similar to F - and Cl-. If these anions are present, use a weak eluent (e.g.,
5 mM Na2B4O7) for greater resolution.
OTHER METHODS: This is P&CAM 339 in a revised format [5]. Alternate methods are 7902 for fluoride and P&CAM 268 for
sulfate [6].
NIOSH Manual