Page:NIOSH Manual of Analytical Methods - 7902.pdf/1

 FLUORIDES, aerosol and gas by ISE F

MW: 18.998

CAS: (HF) 7664-39-3

METHOD: 7902, Issue 2

RTECS: (HF) MW7875000

EVALUATION: PARTIAL

OSHA : 2.5 mg/m 3 (fluorides); 3 ppm (HF) NIOSH: 2.5 mg/m 3 (fluorides); 3 ppm (HF); STEL 6 ppm (HF) ACGIH: 2.5 mg/m 3 (fluorides); C 3 ppm (HF) (1 ppm HF = 0.818 mg/m 3 @ NTP)

7902

PROPERTIES:

Issue 1: 15 February 1984 Issue 2: 15 August 1994

HF: liquid; BP 19.5 °C; fluoride salts liberate HF in presence of acids

SYNONYMS: sodium fluoride (CAS #7681-49-4); hydrogen fluoride; hydrofluoric acid; cryolite; sodium hexafluoroaluminate (CAS SAMPLING SAMPLER:
 * 1) 13775-53-6).

MEASUREMENT

FILTER + TREATED PAD (0.8-µm cellulose ester membrane + Na 2CO 3-treated cellulose pad)

TECHNIQUE:

ION-SPECIFIC ELECTRODE

ANALYTE:

fluoride ion (F )

FLOW RATE:

1 to 2 L/min

FILTER (particulate F ):

VOL-MIN: -MAX:

12 L @ 2.5 mg/m 3 800 L

SHIPMENT:

routine

SAMPLE STABILITY:

stable

BLANKS:

2 to 10 field blanks per set

fuse in NaOH, dissolve in 50 mL water + TISAB

TREATED FILTER (gaseous F ):

extract in 50 mL water + TISAB

CALIBRATION:

standard F

RANGE:

0.03 to 1.2 mg F

ESTIMATED LOD:

3 µg F

PRECISION (Sr):

0.017 @ 55 to 220 µg per sample [2]

solutions in TISAB per sample

per sample [1]

ACCURACY RANGE STUDIED:

not studied

BIAS:

not determined

ˆ ): OVERALL PRECISION (S rT ACCURACY:

not determined not determined

APPLICABILITY: The working range is 0.12 to 8 mg/m 3 for a 250-L air sample. The method applies to mining samples, and samples from the aluminum reduction, ceramic, glass etching, electroplating, semi-conductor, and fluorochemical industri es. If other aerosols are present, gaseous fluoride may be underestimated owing to sorption on collected particles, with concur rent overestimation of particulate/gaseous fluoride ratio [3-8].

INTERFERENCES: In samples containing cryolite, aluminum is sufficiently concentrated to give erroneous fluoride concentrations [3]. Hydroxide ion greater than 1/10 of the fluoride level will interfere positively. Fe 3+, Si4+ , and Al 3+ give a negative interference. Concentrations >8 µg/mL of these elements cannot be suppressed [9]. The TISAB suppresses up to 500 µg/mL Fe 3+ and up to 90 µg/mL Si 4+.

OTHER METHODS: This revises method 7902 [10] which was withdrawn on 5/15/89. The method was originally based on a method by Elfers and Decker [11], and NIOSH method S176 for HF [2]. Method 7903 (Acids, Inorganic) is an alternative met hod for HF. Method 7906 (Fluorides by IC) employs the same sampling procedure, but uses ion chromatography for measurement.

NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 8/15/94