National Institute for Occupational Safety and Health

“ Acids, particularly HF, are extremely corrosive to skin, eyes, and mucous membranes. HF will attack glass. Plastic labware is recommended. Wear gloves, lab coat, and safety glasses while handling acids. All work should be performed with adequate ventilation for personnel and equipment. It is imperative that acid be added to water in order to avoid a violent exothermic reaction [11,12] . SAMPLING, SAMPLE TRANSPORT AND STORAGE: 1.
Prior to sampling, load each clean sampler, first with a sampling (impregnated) filter, then with a prefilter, separating the filters with a spacer. ”

“ Place a 10 mL aliquot of fluoride standard solution into a 100 mL volumetric flask, dilute to the mark and mix thoroughly. The solution is stable for at least 4 weeks at room temperature. 9.
To prepare the impregnated filter, evenly distribute 120 μL 0.75 M Na2CO3 over the surface of the filter and allow to dry at room temperature for several hours.
See Special Precautions 1.
Sampler: 37-mm diameter cellulose nitrate pre-filter, 0.8 μm pore size, 37-mm impregnated cellulose nitrate filter. The untreated filter collects particulate fluorides, while the impregnated filter collects HF vapor. ”

“ Recovery of gaseous HF is reduced at high humidity.
NIOSH Manual of Analytical Methods (NMAM) , Fifth Edition PARTICULATE FLUORIDES and HYDROFLUORIC ACID: METHOD 7906, Issue 2, dated 20 May 2014 - Page 2 of 6
OTHER METHODS: This method updates NIOSH 7906 [7] by providing full method accuracy information, and specifies the use of an impregnated filter instead of a treated cellulose pad. The procedure, which is consistent with ISO 21438-3 [6] , replaces NIOSH 7903 [8] for the determination of particulate fluorides and gaseous HF in workplace air samples. ”