ASTM D4765-13(2018)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D4765 − 13 (Reapproved 2018)
Standard Test Method for
Measurement of Fluorides in Workplace Atmospheres by
Ion-Selective Electrodes
This standard is issued under the fixed designation D4765; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope D5337Practice for Flow RateAdjustment of Personal Sam-
pling Pumps
1.1 This test method covers the simultaneous collection and
E1370Guide for Air Sampling Strategies for Worker and
separate measurements of gaseous fluoride (for example,
Workplace Protection
hydrogen fluoride) and particulate fluoride found in certain
industrial workplaces. The gaseous fluorides and particulate
3. Terminology
fluorides collected are reported in terms of fluoride. The
3.1 Definitions—For definitions of terms used in this test
method covers sample collection, preparation, and fluoride
method, refer to Terminology D1356.
measurement.
1.2 The procedure is not applicable to the collection or
4. Summary of Test Method
analysis of gaseous fluoro compounds (for example, fluorocar-
4.1 Particulate material from a measured volume of air is
bon or fluorosulfur compounds).
collected by means of a membrane filter. Gaseous fluoride,
1.3 The values stated in SI units are to be regarded as
from the sample of air, is absorbed by an alkali-impregnated
standard. No other units of measurement are included in this cellulose pad placed behind the membrane filter. The mem-
standard.
brane filter and collected solids are made alkaline, ashed, and
the residue fused with additional alkali. Finally, the fluoride is
1.4 This standard does not purport to address all of the
determined in a solution of the melt by use of a fluoride
safety concerns, if any, associated with its use. It is the
ion-selective electrode. Gaseous fluoride is determined in an
responsibility of the user of this standard to establish appro-
aqueous extract of the cellulose pad, also by means of the
priate safety, health, and environmental practices and deter-
fluoride ion-selective electrode.
mine the applicability of regulatory limitations prior to use.
1.5 This international standard was developed in accor-
5. Significance and Use
dance with internationally recognized principles on standard-
5.1 The capability of this test method to collect and quan-
ization established in the Decision on Principles for the
titate both particulate and gaseous fluorides over the ranges
Development of International Standards, Guides and Recom-
normally encountered in industrial atmospheres makes it ap-
mendations issued by the World Trade Organization Technical
plicableforindustrialhygieneevaluationandcontrolpurposes.
Barriers to Trade (TBT) Committee.
The recommended range of this test method is from 0.005 to 5
− 3
2. Referenced Documents
mg F /m air.
2.1 ASTM Standards:
6. Interferences
D1193Specification for Reagent Water
6.1 Because an ion-selective electrode responds to ionic
D1356Terminology Relating to Sampling and Analysis of
activity, insoluble and complex forms of fluoride must be
Atmospheres
released by appropriate combinations of fusion, adjustment of
D4840Guide for Sample Chain-of-Custody Procedures
pH, and addition of complexing agents.
6.2 Filter Materials—Not all filter materials can be used
This test method is under the jurisdiction of ASTM Committee D22 on Air
effectively for sampling particulate fluorides in workplace air.
Qualityand is the direct responsibility of Subcommittee D22.04 on WorkplaceAir
Quality.
Cellulosicmembranefiltersarethemostsuitablefiltertypesfor
Current edition approved Dec. 1, 2018. Published December 2018. Originally
sampling of fluorides. Several manufacturers offer mixed-
approved in 1988. Last previous edition approved in 2013 as D4765–13. DOI:
cellulose ester filters commercially; nevertheless it is essential
10.1520/D4765-13R18.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or to check the quality of each filter batch used for sampling.
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
6.3 Acidity (pH) and ionic strengths of fluoride standard
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. solutions must be matched to those of samples.
Copyright ©ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA19428-2959. United States
D4765 − 13 (2018)
6.4 Temperature of sample and standard solutions must be (NH Cl)in500mLwater.Add67mLofammoniumhydroxide
controlled within 62°C. (NH OH) (sp gr=0.90) and dilute to 1 L with water.
8.5 Fluoride Solution, Standard (100 µg/mL)—Dissolve
7. Apparatus
0.2211gsodiumfluoride(NaF,driedat105°Cfor2h)inwater
7.1 Personal Sampling Pump, capable of maintaining con-
and dilute to volume in a 1-L volumetric flask.
stant air flow (65 %) in the range 1–5 L/min through a filter
8.6 Ethanol, analytical grade.
holder(7.2)containinga0.8-µmporesizecellulosicmembrane
8.7 Borate-Carbonate Fusion Mixture—Thoroughly mix a
filter(7.3)andcellulosepad(7.4)foraperiodofupto8hours.
1+2 (w/w) combination of sodium tetraborate (Na B O ) and
2 4 7
7.2 Filter Holder—For sampling of inhalable fraction of
sodium carbonate (Na CO ).
2 3
aerosols, of suitable diameter for the filters (for example,
8.8 Hydrochloric Acid (1+1)—Mix one part hydrochloric
37-mm; see 7.3). The holder shall be numbered for identifica-
acid to one part water (8.2) as a homogeneous solution.
tion.
7.3 Membrane Filter, of mixed-cellulose esters (MCE),
9. Sampling
0.8-µm pore size, and of diameter to fit the filter holder (see
9.1 Cellulose Pad Impregnation—Moisten the cellulose pad
7.2).
(7.4) with a measured volume of alkaline fixative solution (see
7.4 Cellulose Pad, of size to fit the filter holder (see 7.2).
8.3); 0.8 mLis required for a pad of 37-mm diameter. Dry the
The pad is commercially available as a plain, unimpregnated
pad at 105°C for 30 to 45 min, or allow to dry overnight at
pad or impregnated with alkali (8.3).
room temperature in a dessicator.
7.5 Crucibles,20-mL,nickel,platinum,orsuitablealloysof 9.1.1 Preparation of alkali-impregnated pads must be car-
nickel and chromium. riedoutinalow-fluorideenvironmentwithminimumpotential
for contamination.
7.6 Fluoride Ion-Selective Electrode.
9.2 SamplerAssembly—Assemblethefilterholder,inserting
7.7 Reference Electrode,calomeltype,preferablycombined
an impregnated pad with membrane filter atop it, and seal the
with the fluoride ion-selective electrode.
assembly against air leakage. Close the inlet and outlet
7.8 Electrometer or Expanded Scale pH Meter, with a
openings of the filter holder.
millivolt scale for measurement of potentials.
9.3 Personal Sampling Pump—Use personal sampling
NOTE 1—Commercial potentiometers for fluoride sensitive electrodes
are equipped with internal calibration modes. pumps at their design flow rate (1–5 L/min) and calibrated in
accordance with Practice D5337.
7.9 Magnetic Stirring Bar, fluorocarbon-coated.
9.4 Sample Collection—For general information on sam-
7.10 Plastic Beakers, 50 and 100-mL capacities.
pling strategies, refer to Guide E1370.
7.11 Beakers, borosilicate glass, 250-mL capacity.
9.4.1 Equip the worker whose exposure is to be evaluated
7.12 Volumetric Flasks, 50 and 100-mL capacity. with a sampler (9.2) connected by a ca. 75-cm length of
flexible tubing to a belt-supported personal sampling pump
8. Reagents
(9.3). Attach the sampler to place it within the worker’s
personal breathing zone for sampling. Draw air through the
8.1 Purity of Reagents—Reagent grade chemicals shall be
sampler at a calibrated rate of 1–5 L/min; a sampling rate of 2
used in all tests. Unless otherwise indicated, it is intended that
L/min is common. On termination of sampling, record the
all reagents shall conform to the specifications of the Commit-
duration of sampling. Obtain a minimum air sample of 250 L.
tee onAnalytical Reagents of theAmerican Chemical Society,
where such specifications are available.
9.5 Sample Transport—Transport the samplers to the labo-
ratory so as to prevent contamination or damage. Follow
8.2 Purity of Water—Unless otherwise indicated, references
chain-of-custody procedures to document sample traceability
to water shall be understood to mean Type I Reagent Water
in accordance with Guide D4840.
conforming to Specification D1193.
8.3 Alkaline Fixative Solution—Dissolve 25 g of sodium
10. Analysis
carbonate(Na CO )inwater,add20mLglycerol,anddiluteto
2 3
10.1 Fluoride Calibration Standards:
1 L with water.
NOTE 2—These standards may be stored for several months in tightly
8.4 Buffer Solution—Dissolve 60 g of citric acid monohy-
capped polyethylene bottles, under refrigeration.
drate (C H O ·H O), 210 g of sodium citrate
2 8 7 2
10.1.1 Particulate Fluoride—Add 1.0 g borate-carbonate
(Na C H O ·2H O) and 53.5 g of ammonium chl
...