ASTM D4765-98

NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
Designation: D 4765 – 98
Standard Test Method for
Fluorides in Workplace Atmospheres
This standard is issued under the fixed designation D 4765; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope fluoride ion-selective electrode. Gaseous fluoride is determined
in an aqueous extract of the cellulose pad, also by means of the
1.1 This test method covers the simultaneous collection and
fluoride ion-selective electrode.
separate measurements of gaseous and particulate fluoride
found in certain industrial workplaces. The gaseous inorganic
5. Significance and Use
fluorides collected are reported in terms of fluoride; the
5.1 The capability of this test method to collect and quan-
procedure is not applicable to the collection or analysis of other
titate both particulate and gaseous fluorides over the ranges
fluoride-bearing gases (for example, fluorocarbon or fluorosul-
normally encountered in industrial atmospheres makes it ap-
fur compounds). This test method covers sample collection,
plicable for industrial hygiene evaluation and control purposes.
preparation, and fluoride measurement.
The recommended range of this test method is from 0.005 to 5
1.2 This standard does not purport to address all of the
− 3
mg F /m air.
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro-
6. Interferences
priate safety and health practices and determine the applica-
6.1 Because an ion-selective electrode responds to ionic
bility of regulatory limitations prior to use.
activity, insoluble and complex forms of fluoride must be
2. Referenced Documents released by appropriate combinations of fusion, adjustment of
pH, and addition of complexing agents.
2.1 ASTM Standards:
2 6.2 Acidity (pH) and ionic strengths of fluoride standard
D 1193 Specification for Reagent Water
solutions must be matched to those of samples.
D 1356 Terminology Relating to Sampling and Analysis of
6.3 Temperature of sample and standard solutions must be
Atmospheres
controlled within 6 2°C.
D 1357 Practice for Planning the Sampling of the Ambient
Atmosphere
7. Apparatus
D 5337 Practice for Flow Rate for Calibration of Personal
3 7.1 Personal Sampling Pump, Equipped with a flow-
Sampling Pumps
monitoring device (rotameter, critical orifice) or a constant-
flow device capable of drawing 2 L/min of air through the
3. Terminology
0.8-μm membrane filter and pad for a period of 8 h.
3.1 Definitions—For definitions of terms used in this test
7.2 Filter Holder—Plastic holders of the preloaded personal
method, refer to Terminology D 1356.
monitor type, that accept filters of 37-mm diameter, are
4. Summary of Test Method preferred. The holder is to be numbered for identification.
7.3 Membrane Filter, of mixed-cellulose esters, 0.8-μm
4.1 Particulate material from a measured volume of air is
pore size, and of diameter to fit the filter holder (see 7.2).
collected by means of a membrane filter. Gaseous fluoride,
7.4 Cellulose Pad, of size to fit the filter holder (see 7.2).
from the sample of air, is absorbed by an alkali-impregnated
The pad is commercially available as a plain, unpregnated pad
cellulose pad placed immediately behind the membrane filter.
or as an alkali-impregnated pad.
The membrane filter and collected solids are made alkaline,
7.5 Crucibles, 20-mL, nickel, Inconel, or platinum.
ashed, and the residue fused with additional alkali. Finally, the
7.6 Fluoride Ion-Selective Electrode.
fluoride is determined in a solution of the melt by use of a
7.7 Reference Electrode, calomel type, preferably combined
with the fluoride ion-selective electrode.
7.8 Electrometer or Expanded Scale pH Meter, with a
This test method is under the jurisdiction of ASTM Committee D-22 on
millivolt scale for measurement of potentials.
Sampling and Analysis of Atmospheres and is the direct responsibility of Subcom-
mittee D22.04 on Workplace Atmospheres.
7.9 Magnetic Stirrer.
Current edition approved May 10, 1998. Published July 1998. Originally
published as D 4765 – 88. Last previous edition D 4765 – 93.
2 4
Annual Book of ASTM Standards, Vol 11.01. Inconel is a trademark for a group of corrosion-resistant alloys of nickel and
Annual Book of ASTM Standards, Vol 11.03. chromium.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
D 4765
NOTE 1—Preparation of alkali-impregnated pads must be carried out in
7.10 Plastic Beakers, 50 and 100-mL capacities.
a low-fluoride environment with minimum exposure.
7.11 Beakers, 250-mL capacity.
7.12 Volumetric Flasks, 100-mL capacity.
10.2 Reassemble the filter monitor, inserting an impreg-
nated pad and membrane filter, and closing with the filter
8. Reagents
retaining ring and front cover. Seal the assembly against air
8.1 Purity of Reagents—Reagent grade chemicals shall be
leakage by a wrap of masking tape or cellulose shrink bands,
used in all tests. Unless otherwise indicated, it is intended that
covering the crevice between the retaining ring and back cover.
all reagents shall conform to the specifications of the Commit-
Close the inlet and outlet openings of the monitor with plastic
tee on Analytical Reagents of the American Chemical Society,
plugs.
where such specifications are available.
8.2 Purity of Water—Unless otherwise indicated, references
11. Calibration of the Personal Monitoring Pump
to water shall be understood to mean Type I Reagent Water
11.1 Refer to Practice 5337.
conforming to Specification D 1193.
11.2 Select several of the prepared monitors at random for
8.3 Alkaline Fixative Solution—Dissolve 25 g of sodium
calibration of air flow rate with the personal sampling pump
carbonate (Na CO ) in water, add 20 mL glycerol, and dilute to
2 3
(see 7.1). Connect the monitor exit to the sampling pump by
1L.
means of a 75-cm length of hose. Connect the flowmeter
8.4 Buffer Solution (ALCOA)—Dissolve 60 g of citric acid
(preferably a bubble flowmeter, magnehelic flowmeter, or wet
monohydrate (C H O ·H O), 210 g of sodium citrate
2 8 7 2
test meter) to the inlet port of the monitor. Start the pump and
(Na C H O ·2H O) and 53.5 g of ammonium chloride
3 6 5 7 2
adjust its rate, noting the position of the rotameter ball when a
(NH Cl) in 500 mL water. Add 67 mL of ammonium hydroxide
sampling rate of about 2.0 L/min is indicated by use of the
(NH OH) (sp gr = 0.90) and dilute to 1 L with water.
calibration flowmeter and a timer.
8.5 Fluoride Solution, Standard (100 μg/mL)—Dissolve
0.2211 g sodium fluoride (NaF, dried at 105°C for 2 h) in water
NOTE 2—Calibration of pumps with monitors in both in-line and
open-face modes showed no significant difference.
and dilute to volume in a 1-L volumetric flask.
8.6 Ethanol, Denatured—Formula 30 denatured alcohol is
12. Calibration
satisfactory.
8.7 Borate-Carbonate Fusion Mixture—Intimately mix a 12.1 Fluoride Standards, Particulate—Add 1.0 g borate-
carbonate fusion mixture to each of four 250-mL beakers
1+2 (w/w) combination of sodium tetraborate (Na B O ) and
2 4 7
sodium carbonate (Na CO ). containing 10 mL of water and 50 mL of buffer solution (8.4).
2 3
Add a few drops of (1 + 1) hydrochloric acid (see 8.8) and add
8.8 Hydrochloric Acid (1+1)—Mix one part hydrochloric
various size aliquots (1, 5, 10, and 25 mL) of 100 μg/mL
acid to one part distilled water as a solution.
standard fluoride solution (see 8.5) to produce a series of
9. Sampling
−
working standards (1, 5, 10, and 25 μg/F /mL). Transfer to a
9.1 For general information on sampling, refer to Practice
100-mL volumetric flask, and dilute to volume with water.
D 1357.
NOTE 3—These standards may be stored for several months in tightly
9.2 Equip the worker whose exposure is to be evaluated
capped polyethylene bottles, under refrigeration.
with a personal monitor connected by a 75-cm length of hose
to a belt-supported sampling pump. Attach the monitor to the 12.2 For calibration of the electrode, pour about 20 mL of
worker’s collar and remove the plug for closed-face sampling. the working standard solution into a plastic beaker containing
Air is drawn through the filter at the calibrated rate of a TFE-fluorocarbon-coated stirring bar. Adjust solution to
approximately 2.0 L/min and maintained at that rate by within 6 2°C of an arbitrarily selected standard temperature.
occasional checking and adjustment. On termination of sam- Insert the fluoride and reference electrodes into the constantly
pling, note the duration of sampling, reseal the monitor and stirred solution and measure the potential after 2 min. Repeat
return the monitor to the laborator
...