1、Designation: D 7295 06Standard Practice forSampling and Determination of Hydrogen Cyanide (HCN) inCombustion Effluents and Other Stationary Sources1This standard is issued under the fixed designation D 7295; the number immediately following the designation indicates the year oforiginal adoption or,
2、in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice is used to determine the concentration ofgaseous hydrogen cyanide
3、(HCN) from any combustion deviceor atmosphere where cyanide may be present. While primarilydesigned for the measurement of gas phase HCN, the samplecollection described in this practice also includes cyanide ion(CN-) absorbed particles that may be present in the samplingatmosphere.1.1.1 Samples can
4、be collected from a closed chamber suchas the NBS smoke box described in Test Method E 662provided it is equipped with sampling ports.1.1.2 Open chambers such as industrial work areas or largescale fires can be monitored for HCN with this practice.1.1.3 The HCN emissions of a flow through system can
5、 bedetermined by sampling from its discharge stack. Examples ofsuch systems include large scale manufacturing applicationsand the cone calorimeter described in Test Method E 1354.1.2 This practice can be used to monitor HCN levels in labscale fire smoke effluents in order to estimate toxicity of gas
6、esproduced from burning materials. See Guide E 800.1.3 The concentration range of hydrogen cyanide will bedependent on the volume of gas sampled, the volume ofsodium hydroxide solution placed in the impinger duringsampling, and the analytical method used to measure cyanide.For example, the lower lim
7、it of detection would be 0.002-mg/m3when 0.1-m3of combustion effluent is collected into100-mL sodium hydroxide solution based on a detection limitof 0.002 mg/L cyanide in the impinger solution when using theflow injection analysis (FIA) system described in Test MethodD 6888.1.4 This standard does no
8、t purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standard
9、s:D 1193 Specification for Reagent WaterD 1356 Terminology Relating to Sampling and Analysis ofAtmospheresD 2036 Test Methods for Cyanides in WaterD 2777 Practice for Determination of Precision and Bias ofApplicable Test Methods of Committee D19 on WaterD 3154 Test Method for Average Velocity in a D
10、uct (PitotTube Method)D 3614 Guide for Laboratories Engaged in Sampling andAnalysis of Atmospheres and EmissionsD 3685/D 3685M Test Methods for Sampling and Determi-nation of Particulate Matter in Stack GasesD 4841 Practice for Estimation of Holding Time for WaterSamples Containing Organic and Inorg
11、anic ConstituentsD 5337 Practice for Flow Rate Calibration of PersonalSampling PumpsD 6696 Guide for Understanding Cyanide SpeciesD 6888 Test Method for Available Cyanide with LigandDisplacement and Flow Injection Analysis (FIA) UtilizingGas Diffusion Separation and Amperometric DetectionE 337 Test
12、Method for Measuring Humidity with a Psy-chrometer (the Measurement of Wet- and Dry-Bulb Tem-peratures)E 662 Test Method for Specific Optical Density of SmokeGenerated by Solid MaterialsE 800 Guide for Measurement of Gases Present or Gener-ated During FiresE 1354 Test Method for Heat and Visible Smo
13、ke ReleaseRates for Materials and Products Using an Oxygen Con-sumption Calorimeter3. Terminology3.1 Refer to Terminology D 1356 for terminology related tosampling and analysis of atmospheres.1This practice is under the jurisdiction of ASTM Committee D22 on Air Qualityand is the direct responsibilit
14、y of Subcommittee D22.03 on Ambient Atmospheresand Source Emissions.Current edition approved Oct. 1, 2006. Published October 2006.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.2 For definitions of terms related to cyanide testing
15、, referto Guide D 6696 and Test Method D 6888.3.3 For definitions of terms related to the measurement ofgases present or generated during fires, refer to Guide E 800.3.4 For additional information related to sampling andanalysis of atmospheres, see Guide D 3614.4. Summary of Practice4.1 A known volu
16、me of gaseous sample is bubbled throughan impinger containing 0.1M sodium hydroxide solutionutilizing a calibrated pumping system. Particulates that maypass through the impinger are captured on a glass fiber filterthen recombined back into the impinger solution prior toanalysis. Because HCN is solub
17、le in aqueous solutions, it maybe present in water droplets formed from either a wet scrubbersystem or condensation in the stack. Because of this, samplesthat contain moist air should be sampled near isokineticconditions.4.2 During the sampling process, hydrogen cyanide (HCN)is converted to cyanide
18、ion (CN-) in the sodium hydroxidesolution. The CN-is analyzed with a flow injection analysis(FIA) system described in Test Method D 6888 or with asuitable analytical method such as ion chromatography de-scribed in Test Methods D 2036.4.2.1 Colorimetric and ion selective electrode methods, alsodescri
19、bed in Test Methods D 2036 can be used for screeningpurposes.4.3 The concentration of HCN in the atmosphere or stack iscalculated as described in 9.6.5. Significance and Use5.1 Hydrogen cyanide is highly toxic. In relatively lowquantities, hydrogen cyanide can cause asphyxia and death.5.2 The Nation
20、al Fire Protection Association has assigned aflammability rating of 4 (severe fire hazard) to hydrogencyanide.6. Apparatus6.1 Sample Collection Train6.1.1 Constant Flow Pumping SystemPumps used to col-lect samples should be able to accurately pump from 0.1-L/minto 15-L/min or at the desired flow rat
21、e. Personal industrialhygiene sampling pumps or high volume sampling pumps maybe utilized. More than one sample can be collected with asingle pump using a manifold with flow control valves. Thesystem should be calibrated as described in Practice D 5337 orusing a suitable commercially available calib
22、rator.6.1.2 Impinger Sample Collection VesselsStandard minior midget impingers with standard tip. Greenberg-Smith im-pingers equipped with a standard tip with 500-mL capacitymay be used when larger flow rates are desired. Impingerconnections should consist of leak free ground glass joints toavoid th
23、e loss of HCN during sampling and should be free ofany silicone grease. The use of a single impinger has shown toyield an average of 97 % efficiency in combustion effluents;however, higher efficiencies are possible using additionalimpingers in series. Without prior knowledge of the atmo-sphere, it i
24、s recommended to use a backup impinger todetermine if breakthrough occurs. Test each impinger forcyanide as a separate sample in order to demonstrate captureefficiency; mathematically combine the results by adding theobserved concentrations.6.1.3 Sample Collection Tubing and ProbesCollectiontubing a
25、nd probes should be constructed of inert material suchPTFE or PTFE-lined stainless steel. Vinyl tubing can be usedin the sample train where flexible tubing is necessary, but theaforementioned are preferred. The sample lines should beheated at 120 6 5C when sampling stack emissions in moistair in ord
26、er to prevent condensate from forming in the sampletrain.6.1.4 Glass Fiber FiltersType A/E, 1 m binder freeborosilicate glass fiber filter and cassette assembly cartridge forair sampling applications. The filters are used between theimpingers and pumping system to capture fine particulates thatmay p
27、ass through the impingers and to protect the pumpingsystem. It is recommended to use 13-mm filters for mini-impingers and 47-mm filters for Greenberg-Smith impingers.6.1.5 Duplicate and Matrix Spike Sample TrainsIt isrecommended to setup duplicate impingers to evaluate preci-sion. In addition, a sec
28、ond set of impingers can be fortified witha known amount of cyanide (see 8.11) to evaluate recovery.Fig. 1 shows an example of such a system.6.1.6 ThermometerMeasure the temperature of the stackor atmosphere with a mercury thermometer or an equivalentdigital thermometer capable of accurately reading
29、 within60.1C.7. Interferences7.1 Sulfide, aldehydes, and oxidizing agents in the atmo-sphere are possible interferences.7.2 Prior to conducting sampling and analysis, review 9.4 inorder to avoid cyanide degradation or inaccurate results.8. Reagents and Materials8.1 Purity of ReagentsReagent grade ch
30、emicals shall beused in all tests. Unless otherwise indicated, it is intended thatall reagents shall conform to the specifications of theAmericanChemical Society, where such specifications are available2.Other grades may be used, provided it is first ascertained thatthe reagent is of sufficiently hi
31、gh purity to permit its usewithout lessening the accuracy of the determination.8.2 Purity of WaterUnless otherwise indicated, referencesto water shall be understood to mean reagent water conformingto Type I, II, or III of Specification D 1193.8.3 Impinger Solution(0.10 M NaOH)In a 1-Lvolumet-ric fla
32、sk, dissolve 4.0 g NaOH in approximately 800-mLlaboratory water and dilute to 1L.8.4 Ethylenediamine (EDA) SolutionWeigh 3.5 g EDAinto a 100-mL volumetric flask and dilute to volume withwater.8.5 Cadmium Chloridegranular, powdered.2Reagent Chemicals, American Chemical Society Specifications, Am. Che
33、micalSoc., Washington, DC. For suggestions on the testing of reagents not listed by theAmerican chemical Society, see Analar Standards for Laboratory Chemicals, BDHLtd., Poole, Dorset, U.K., and the United States Pharmacopeia.D72950628.6 Lead Acetate Test Stripsused to test for the presenceof sulfid
34、e in the impinger solutions.8.7 Leur Lock Syringe Filter0.45 m filter attached tosyringe8.8 KI Starch Paper Test Stripsused to indicate thepresence of oxidizing agents8.9 Sodium ArseniteNaAsO2is used to neutralize oxidiz-ing agents8.10 pH Indicator Stripswide range pH paper.8.11 Cyanide Matrix Spike
35、 Solution (1000 g/mL CN-)Dissolve 2.51 g of KCN and 2.0 g of NaOH in 1 L of water.Standardize with silver nitrate solution as described in TestMethods D 2036, paragraph 16.2. Store the solution underrefrigeration and check concentration approximately every sixmonths and correct if necessary. Commerc
36、ially prepared solu-tions are also available and can be used for spiking purposes.(WarningBecause of the toxicity of cyanide, great care mustbe exercised in its handling. Acidification of cyanide solutionsproduces toxic hydrocyanic acid (HCN). All manipulationsmust be done in the hood so that any HC
37、N gas that mightescape is safely vented.)9. Procedure9.1 Stack Evaluation (Flow Through Systems)9.1.1 Determine the velocity of the stack as described inTest Method D 3154 or US EPA Method 23.9.1.2 Because HCN is soluble in aqueous solutions, it maybe present in water droplets formed from either a w
38、et scrubbersystem or condensation in the stack. Because of this, samplesthat contain moist air should be sampled near isokineticconditions. To determine if the moisture in the stack issaturated, test with the wet bulb/dry bulb procedure describedin Test Method E 337 or estimate the moisture content
39、by USEPA Method 44.9.1.3 If isokinetic sampling is required, see Test MethodsD 3685/D 3685M or US EPAMethod 55to determine the probediameter and sampling flow rate. This flow rate will bemaintained during the entire sampling event.9.2 Open and Closed Chamber Systems (Non-Flow ThroughSystems)9.2.1 Wh
40、en samples are collected from workplace monitor-ing areas or closed chamber combustion devices, the samplingrate (which will determine the volume of sample collected)should be selected based on the expected concentration ofHCN or the required detection limit.9.2.2 Since open and closed chamber syste
41、ms are not flowdependent (that is, there is no measurable flow) isokineticsampling is not possible. Adequate sampling rates and sam-pling times should be used to collect a representative sample.When comparing combustion emissions from various materi-als, it is recommended to keep the sampling rate c
42、onstant foreach test burn.9.3 Sampling9.3.1 Assemble the sample train with an impinger thatcontains a known volume of the impinger solution (0.1 MNaOH). The volume of impinger solution will depend on thesize of impinger. It is recommended to use 100 mL of the3Method 2, Velocity - S-type Pitot, U. S.
43、 Environmental Protection Agency4Method 4, Moisture Content, U. S. Environmental Protection Agency5Method 5, Particulate Matter, U. S. Environmental Protection AgencyFIG. 1 Example of Sample Train (Closed Chamber Sampling, Non-Isokinetic)D7295063impinger solution when using Greenberg-Smith impingers
44、 or20 mL of impinger solution when using mini-impingers.Connect a glass fiber filter (see 6.1.4) between each impingerand the pumping system. The filter will capture any fineparticulate that passes through the impinger and will protect thepumping system and valves.NOTE 1This practice is primarily us
45、ed to determine the concentrationof HCN and any particulate cyanides that are easily dissociated into freecyanide. To specifically determine the particulate cyanides, a prefilter canbe placed prior to the impinger(s). After sampling, this filter and thecaptured solids are extracted with 0.1M NaOH th
46、en analyzed per the testmethods described in 9.5. If the particles contain strong-acid dissociablemetal cyanide complexes such as potassium ferricyanide or potassiumferrocyanide, it will be necessary to digest the extract and particles withthe total cyanide procedure described in Test Methods D 2036
47、, TestMethod A prior to analysis.9.3.2 If necessary, heat the sample probe and transfer line to120C during sampling in order to prevent condensation in thesample probe and transfer line.9.3.3 Check the sample train system for leaks prior tosampling. Start the pumps and collect sample for a knownamou
48、nt of time. The sampling time will vary depending on theamount of cyanide emissions that are expected. Stack samplesare typically sampled for 30 to 60 minutes; however, firesmoke effluents may require substantially shorter samplingtimes depending on the combusted material. Workplace envi-ronments ma
49、y need sampled for longer periods of time in orderto achieve the required detection limits.9.3.4 If any of the impinger solution is lost from volatiliza-tion during sampling, adjust to the original volume withreagent water upon completion of sampling, or measure theremaining volume with a graduated cylinder. Transfer theimpinger solutions into labeled polyethylene bottles.9.3.5 When sampling acidic atmospheres, verify that the pHof each impinger solution is greater than pH 12 with indicatingtest strips, pH meter, or with an indicating solution such asAlizarin Y
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