EPA Method 7A Determination Of Nitrogen Oxide Emissions From Stationary Sources (Ion Chromatographic Method)
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ID： |
432A0FBB7A5C46DC8DBA035365002C26 |
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文件大小(MB)： |
0.03 |
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页数： |
12 |
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文件格式： |
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日期： |
2000-2-12 |
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文本摘录（文本识别可能有误，但文件阅览显示及打印正常，pdf文件可进行文字搜索定位）：
671,METHOD 7A - DETERMINATION OF NITROGEN OXIDE EMISSIONS,FROM STATIONARY SOURCES,(ION CHROMATOGRAPHIC METHOD),NOTE: This method does not include all of the,specifications (e.g., equipment and supplies) and procedures,(e.g., sampling and analytical) essential to its,performance. Some material is incorporated by reference,from other methods in this part. Therefore, to obtain,reliable results, persons using this method should have a,thorough knowledge of at least the following additional test,methods: Method 1, Method 3, Method 5, and Method 7.,1.0 Scope and Application.,1.1 Analytes.,Analyte CAS No. Sensitivity,Nitrogen oxides (NOx),as NO2, including:,Nitric oxide (NO),Nitrogen dioxide (NO2),10102-43-9,10102-44-0,65-655 ppmv,1.2 Applicability. This method is applicable for the,determination of NOx emissions from stationary sources.,1.3 Data Quality Objectives. Adherence to the,requirements of this method will enhance the quality of the,data obtained from air pollutant sampling methods.,2.0 Summary of Method.,672,A grab sample is collected in an evacuated flask,containing a dilute sulfuric acid-hydrogen peroxide,absorbing solution. The nitrogen oxides, excluding nitrous,oxide (N2O), are oxidized to nitrate and measured by ion,chromatography.,3.0 Definitions. [Reserved],4.0 Interferences.,Biased results have been observed when sampling under,conditions of high sulfur dioxide concentrations (above 2000,ppm).,5.0 Safety.,5.1 This method may involve hazardous materials,operations, and equipment. This test method may not address,all of the safety problems associated with its use. It is,the responsibility of the user of this test method to,establish appropriate safety and health practices and to,determine the applicability of regulatory limitations prior,to performing this test method.,5.2 Corrosive reagents. The following reagents are,hazardous. Personal protective equipment and safe,procedures are useful in preventing chemical splashes. If,contact occurs, immediately flush with copious amounts of,water at least 15 minutes. Remove clothing under shower and,673,decontaminate. Treat residual chemical burns as thermal,burns.,5.2.1 Hydrogen Peroxide (H2O2). Irritating to eyes,skin, nose, and lungs.,5.2.2 Sulfuric Acid (H2SO4). Rapidly destructive to,body tissue. Will cause third degree burns. Eye damage may,result in blindness. Inhalation may be fatal from spasm of,the larynx, usually within 30 minutes. May cause lung,tissue damage with edema. 3 mg/m3 will cause lung damage in,uninitiated. 1 mg/m3 for 8 hours will cause lung damage or,in higher concentrations, death. Provide ventilation to,limit inhalation. Reacts violently with metals and,organics.,6.0 Equipment and Supplies.,6.1 Sample Collection. Same as in Method 7, Section,6.1.,6.2 Sample Recovery. Same as in Method 7, Section,6.2, except the stirring rod and pH paper are not needed.,6.3 Analysis. For the analysis, the following,equipment and supplies are required. Alternative,instrumentation and procedures will be allowed provided the,calibration precision requirement in Section 10.1.2 and,audit accuracy requirement in Section 11.3 can be met.,674,6.3.1 Volumetric Pipets. Class A; 1-, 2-, 4-, 5-ml,(two for the set of standards and one per sample), 6-, 10-,and graduated 5-ml sizes.,6.3.2 Volumetric Flasks. 50-ml (two per sample and,one per standard), 200-ml, and 1-liter sizes.,6.3.3 Analytical Balance. To measure to within 0.1,mg.,6.3.4 Ion Chromatograph. The ion chromatograph,should have at least the following components:,6.3.4.1 Columns. An anion separation or other column,capable of resolving the nitrate ion from sulfate and other,species present and a standard anion suppressor column,(optional). Suppressor columns are produced as proprietary,items; however, one can be produced in the laboratory using,the resin available from BioRad Company, 32nd and Griffin,Streets, Richmond, California. Peak resolution can be,optimized by varying the eluent strength or column flow,rate, or by experimenting with alternative columns that may,offer more efficient separation. When using guard columns,with the stronger reagent to protect the separation column,the analyst should allow rest periods between injection,intervals to purge possible sulfate buildup in the guard,column.,6.3.4.2 Pump. Capable of maintaining a steady flow,as required by the system.,675,6.3.4.3 Flow Gauges. Capable of measuring the,specified system flow rate.,6.3.4.4 Conductivity Detector.,6.3.4.5 Recorder. Compatible with the output voltage,range of the detector.,7.0 Reagents and Standards.,Unless otherwise indicated, it is intended that all,reagents conform to the specific……
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