ASTM D7295-06
(Practice)Standard Practice for Sampling and Determination of Hydrogen Cyanide (HCN) in Combustion Effluents and Other Stationary Sources
Standard Practice for Sampling and Determination of Hydrogen Cyanide (HCN) in Combustion Effluents and Other Stationary Sources
SIGNIFICANCE AND USE
Hydrogen cyanide is highly toxic. In relatively low quantities, hydrogen cyanide can cause asphyxia and death.
The National Fire Protection Association has assigned a flammability rating of 4 (severe fire hazard) to hydrogen cyanide.
SCOPE
1.1 This practice is used to determine the concentration of gaseous hydrogen cyanide (HCN) from any combustion device or atmosphere where cyanide may be present. While primarily designed for the measurement of gas phase HCN, the sample collection described in this practice also includes cyanide ion (CN-) absorbed particles that may be present in the sampling atmosphere.
1.1.1 Samples can be collected from a closed chamber such as the NBS smoke box described in Test Method E 662 provided it is equipped with sampling ports.
1.1.2 Open chambers such as industrial work areas or large scale fires can be monitored for HCN with this practice.
1.1.3 The HCN emissions of a flow through system can be determined by sampling from its discharge stack. Examples of such systems include large scale manufacturing applications and the cone calorimeter described in Test Method E 1354.
1.2 This practice can be used to monitor HCN levels in lab scale fire smoke effluents in order to estimate toxicity of gases produced from burning materials. See Guide E 800.
1.3 The concentration range of hydrogen cyanide will be dependent on the volume of gas sampled, the volume of sodium hydroxide solution placed in the impinger during sampling, and the analytical method used to measure cyanide. For example, the lower limit of detection would be 0.002-mg/m3 when 0.1-m3 of combustion effluent is collected into 100-mL sodium hydroxide solution based on a detection limit of 0.002 mg/L cyanide in the impinger solution when using the flow injection analysis (FIA) system described in Test Method D 6888.
This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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Designation:D7295–06
Standard Practice for
Sampling and Determination of Hydrogen Cyanide (HCN) in
Combustion Effluents and Other Stationary Sources
This standard is issued under the fixed designation D7295; 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 (´) indicates an editorial change since the last revision or reapproval.
1. Scope priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use.
1.1 This practice is used to determine the concentration of
gaseous hydrogen cyanide (HCN) from any combustion device
2. Referenced Documents
or atmosphere where cyanide may be present. While primarily
2.1 ASTM Standards:
designed for the measurement of gas phase HCN, the sample
D1193 Specification for Reagent Water
collection described in this practice also includes cyanide ion
- D1356 Terminology Relating to Sampling and Analysis of
(CN ) absorbed particles that may be present in the sampling
Atmospheres
atmosphere.
D2036 Test Methods for Cyanides in Water
1.1.1 Samples can be collected from a closed chamber such
D2777 Practice for Determination of Precision and Bias of
as the NBS smoke box described in Test Method E662
Applicable Test Methods of Committee D19 on Water
provided it is equipped with sampling ports.
D3154 Test Method for Average Velocity in a Duct (Pitot
1.1.2 Open chambers such as industrial work areas or large
Tube Method)
scale fires can be monitored for HCN with this practice.
D3614 Guide for Laboratories Engaged in Sampling and
1.1.3 The HCN emissions of a flow through system can be
Analysis of Atmospheres and Emissions
determined by sampling from its discharge stack. Examples of
D3685/D3685M Test Methods for Sampling and Determi-
such systems include large scale manufacturing applications
nation of Particulate Matter in Stack Gases
and the cone calorimeter described in Test Method E1354.
D4841 Practice for Estimation of Holding Time for Water
1.2 This practice can be used to monitor HCN levels in lab
Samples Containing Organic and Inorganic Constituents
scale fire smoke effluents in order to estimate toxicity of gases
D5337 Practice for Flow Rate Calibration of Personal
produced from burning materials. See Guide E800.
Sampling Pumps
1.3 The concentration range of hydrogen cyanide will be
D6696 Guide for Understanding Cyanide Species
dependent on the volume of gas sampled, the volume of
D6888 Test Method for Available Cyanide with Ligand
sodium hydroxide solution placed in the impinger during
Displacement and Flow InjectionAnalysis (FIA) Utilizing
sampling, and the analytical method used to measure cyanide.
Gas Diffusion Separation and Amperometric Detection
For example, the lower limit of detection would be 0.002-
3 3 E337 Test Method for Measuring Humidity with a Psy-
mg/m when 0.1-m of combustion effluent is collected into
chrometer (the Measurement of Wet- and Dry-Bulb Tem-
100-mL sodium hydroxide solution based on a detection limit
peratures)
of 0.002 mg/Lcyanide in the impinger solution when using the
E662 Test Method for Specific Optical Density of Smoke
flow injection analysis (FIA) system described in Test Method
Generated by Solid Materials
D6888.
E800 Guide for Measurement of Gases Present or Gener-
1.4 This standard does not purport to address all of the
ated During Fires
safety concerns, if any, associated with its use. It is the
E1354 Test Method for Heat and Visible Smoke Release
responsibility of the user of this standard to establish appro-
Rates for Materials and Products Using an Oxygen Con-
sumption Calorimeter
This practice is under the jurisdiction ofASTM Committee D22 onAir Quality
and is the direct responsibility of Subcommittee D22.03 on Ambient Atmospheres
3. Terminology
and Source Emissions.
3.1 Refer to Terminology D1356 for terminology related to
Current edition approved Oct. 1, 2006. Published October 2006. DOI: 10.1520/
D7295-06. sampling and analysis of atmospheres.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D7295–06
3.2 For definitions of terms related to cyanide testing, refer determine if breakthrough occurs. Test each impinger for
to Guide D6696 and Test Method D6888. cyanide as a separate sample in order to demonstrate capture
3.3 For definitions of terms related to the measurement of efficiency; mathematically combine the results by adding the
gases present or generated during fires, refer to Guide E800. observed concentrations.
3.4 For additional information related to sampling and 6.1.3 Sample Collection Tubing and Probes—Collection
analysis of atmospheres, see Guide D3614. tubing and probes should be constructed of inert material such
PTFE or PTFE-lined stainless steel. Vinyl tubing can be used
4. Summary of Practice in the sample train where flexible tubing is necessary, but the
aforementioned are preferred. The sample lines should be
4.1 Aknown volume of gaseous sample is bubbled through
heated at 120 6 5°C when sampling stack emissions in moist
an impinger containing 0.1–M sodium hydroxide solution
air in order to prevent condensate from forming in the sample
utilizing a calibrated pumping system. Particulates that may
train.
pass through the impinger are captured on a glass fiber filter
6.1.4 Glass Fiber Filters—Type A/E, 1 µm binder free
then recombined back into the impinger solution prior to
borosilicateglassfiberfilterandcassetteassemblycartridgefor
analysis. Because HCN is soluble in aqueous solutions, it may
air sampling applications. The filters are used between the
be present in water droplets formed from either a wet scrubber
impingers and pumping system to capture fine particulates that
system or condensation in the stack. Because of this, samples
may pass through the impingers and to protect the pumping
that contain moist air should be sampled near isokinetic
system. It is recommended to use 13-mm filters for mini-
conditions.
impingers and 47-mm filters for Greenberg-Smith impingers.
4.2 During the sampling process, hydrogen cyanide (HCN)
-
6.1.5 Duplicate and Matrix Spike Sample Trains—It is
is converted to cyanide ion (CN ) in the sodium hydroxide
-
recommended to setup duplicate impingers to evaluate preci-
solution. The CN is analyzed with a flow injection analysis
sion.Inaddition,asecondsetofimpingerscanbefortifiedwith
(FIA) system described in Test Method D6888 or with a
a known amount of cyanide (see 8.11) to evaluate recovery.
suitable analytical method such as ion chromatography de-
Fig. 1 shows an example of such a system.
scribed in Test Methods D2036.
6.1.6 Thermometer—Measure the temperature of the stack
4.2.1 Colorimetric and ion selective electrode methods, also
or atmosphere with a mercury thermometer or an equivalent
described in Test Methods D2036 can be used for screening
digital thermometer capable of accurately reading within
purposes.
60.1°C.
4.3 The concentration of HCN in the atmosphere or stack is
calculated as described in 9.6.
7. Interferences
7.1 Sulfide, aldehydes, and oxidizing agents in the atmo-
5. Significance and Use
sphere are possible interferences.
5.1 Hydrogen cyanide is highly toxic. In relatively low
7.2 Prior to conducting sampling and analysis, review 9.4 in
quantities, hydrogen cyanide can cause asphyxia and death.
order to avoid cyanide degradation or inaccurate results.
5.2 The National Fire ProtectionAssociation has assigned a
flammability rating of 4 (severe fire hazard) to hydrogen
8. Reagents and Materials
cyanide.
8.1 Purity of Reagents—Reagent grade chemicals shall be
used in all tests. Unless otherwise indicated, it is intended that
6. Apparatus
all reagents shall conform to the specifications of theAmerican
6.1 Sample Collection Train
Chemical Society, where such specifications are available .
6.1.1 Constant Flow Pumping System—Pumps used to col-
Other grades may be used, provided it is first ascertained that
lectsamplesshouldbeabletoaccuratelypumpfrom0.1-L/min
the reagent is of sufficiently high purity to permit its use
to 15-L/min or at the desired flow rate. Personal industrial
without lessening the accuracy of the determination.
hygiene sampling pumps or high volume sampling pumps may
8.2 Purity of Water—Unless otherwise indicated, references
be utilized. More than one sample can be collected with a
to water shall be understood to mean reagent water conforming
single pump using a manifold with flow control valves. The
to Type I, II, or III of Specification D1193.
system should be calibrated as described in Practice D5337 or
8.3 ImpingerSolution—(0.10MNaOH)—Ina1-Lvolumet-
using a suitable commercially available calibrator.
ric flask, dissolve 4.0 g NaOH in approximately 800-mL
6.1.2 Impinger Sample Collection Vessels—Standard mini
laboratory water and dilute to 1L.
or midget impingers with standard tip. Greenberg-Smith im-
8.4 Ethylenediamine (EDA) Solution—Weigh 3.5 g EDA
pingers equipped with a standard tip with 500-mL capacity
into a 100-mL volumetric flask and dilute to volume with
may be used when larger flow rates are desired. Impinger
water.
connections should consist of leak free ground glass joints to
8.5 Cadmium Chloride—granular, powdered.
avoid the loss of HCN during sampling and should be free of
any silicone grease. The use of a single impinger has shown to
yield an average of 97 % efficiency in combustion effluents;
Reagent Chemicals, American Chemical Society Specifications,Am. Chemical
however, higher efficiencies are possible using additional
Soc., Washington, DC. For suggestions on the testing of reagents not listed by the
impingers in series. Without prior knowledge of the atmo-
American chemical Society, see Analar Standards for Laboratory Chemicals, BDH
sphere, it is recommended to use a backup impinger to Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia.
D7295–06
FIG. 1 Example of Sample Train (Closed Chamber Sampling, Non-Isokinetic)
8.6 Lead Acetate Test Strips—used to test for the presence that contain moist air should be sampled near isokinetic
of sulfide in the impinger solutions. conditions. To determine if the moisture in the stack is
8.7 Leur Lock Syringe Filter—0.45 µm filter attached to saturated, test with the wet bulb/dry bulb procedure described
syringe in Test Method E337 or estimate the moisture content by US
8.8 KI Starch Paper Test Strips—used to indicate the EPA Method 4 .
presence of oxidizing agents 9.1.3 If isokinetic sampling is required, see Test Methods
8.9 Sodium Arsenite—NaAsO is used to neutralize oxidiz- D3685/D3685M or US EPAMethod 5 to determine the probe
ing agents diameter and sampling flow rate. This flow rate will be
8.10 pH Indicator Strips—wide range pH paper. maintained during the entire sampling event.
-
8.11 Cyanide Matrix Spike Solution (1000 µg/mL CN )— 9.2 Open and Closed Chamber Systems (Non-Flow Through
Dissolve 2.51 g of KCN and 2.0 g of NaOH in 1 L of water. Systems)
Standardize with silver nitrate solution as described in Test 9.2.1 When samples are collected from workplace monitor-
Methods D2036, paragraph 16.2. Store the solution under ing areas or closed chamber combustion devices, the sampling
refrigeration and check concentration approximately every six rate (which will determine the volume of sample collected)
months and correct if necessary. Commercially prepared solu- should be selected based on the expected concentration of
tions are also available and can be used for spiking purposes. HCN or the required detection limit.
(Warning—Becauseofthetoxicityofcyanide,greatcaremust 9.2.2 Since open and closed chamber systems are not flow
be exercised in its handling.Acidification of cyanide solutions dependent (that is, there is no measurable flow) isokinetic
produces toxic hydrocyanic acid (HCN). All manipulations sampling is not possible. Adequate sampling rates and sam-
must be done in the hood so that any HCN gas that might pling times should be used to collect a representative sample.
escape is safely vented.) When comparing combustion emissions from various materi-
als, it is recommended to keep the sampling rate constant for
9. Procedure
each test burn.
9.1 Stack Evaluation (Flow Through Systems) 9.3 Sampling
9.1.1 Determine the velocity of the stack as described in
9.3.1 Assemble the sample train with an impinger that
Test Method D3154 or US EPA Method 2 . contains a known volume of the impinger solution (0.1 M
9.1.2 Because HCN is soluble in aqueous solutions, it may
NaOH). The volume of impinger solution will depend on the
be present in water droplets formed from either a wet scrubber size of impinger. It is recommended to use 100 mL of the
system or condensation in the stack. Because of this, samples
Method 4, Moisture Content, U. S. Environmental Protection Agency
3 5
Method 2, Velocity - S-type Pitot, U. S. Environmental Protection Agency Method 5, Particulate Matter, U. S. Environmental Protection Agency
D7295–06
impinger solution when using Greenberg-Smith impingers or 9.4.1 Some materials may liberate aldehydes during com-
20 mL of impinger solution when using mini-impingers. bustion. Cyanides can react with aldehydes in aqueous solu-
Connect a glass fiber filter (see 6.1.4) between each impinger tions to form cyanohydrins. If the sampled atmospheres are
and the pumping system. The filter will capture any fine known or suspected to contain formaldehyde, acetaldehyde, or
particulatethatpassesthroughtheimpingerandwillprotectthe other water soluble aldehydes, then add 20-mL of EDA
pumping system and valves. solution(see8.4)to1-Loftheimpingersolution(see8.3)prior
to collecting samples. The addition of EDA will inhibit the
NOTE 1—This practice is primarily used to determine the concentration
reaction of cyanide with aldehydes, which will prevent the loss
of HCN and any particulate cyanides that are easily dissociated into free
of cyanide due to the formation of cyanohydrins.
cyanide. To specifically determine the particulate cyanides, a prefilter can
be placed prior to the impinger(s). After sampling, this filter and the
9.4.2 The sulfide abatement reagent used in the flow injec-
captured solids are extracted with 0.1M NaOH then analyzed per the test
tion analysis of Test Method D6888 will effectively remove up
2-
methods described in 9.5. If the particles contain strong-acid dissociable
to 50-mg/L S . If larger concentrations of sulfide are sus-
metal cyanide complexes such as potassium ferricyanide or potassium
pected, then the samples will require additional sulfide abate-
ferrocyanide, it wi
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