EPA Method 25D Determination Of The Volatile Organic Concentration Of Waste Samples
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ID： |
C33F28AE0D67493E96E9B9C80DA52B2D |
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文件大小(MB)： |
0.47 |
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页数： |
33 |
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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）：
1285,METHOD 25D - DETERMINATION OF THE VOLATILE ORGANIC,CONCENTRATION OF WASTE SAMPLES,NOTE: Performance of this method should not be,attempted by persons unfamiliar with the operation of a,flame ionization detector (FID) or an electrolytic,conductivity detector (ELCD) because knowledge beyond the,scope of this presentation is required.,1.0 Scope and Application.,1.1 Analyte. Volatile Organic Compounds. No CAS No.,assigned.,1.2 Applicability. This method is applicable for,determining the volatile organic (VO) concentration of a,waste sample.,2.0 Summary of Method.,2.1 Principle. A sample of waste is obtained at a,point which is most representative of the unexposed waste,(where the waste has had minimum opportunity to volatilize,to the atmosphere). The sample is suspended in an,organic/aqueous matrix, then heated and purged with nitrogen,for 30 min in order to separate certain organic compounds.,Part of the sample is analyzed for carbon concentration, as,methane, with an FID, and part of the sample is analyzed for,chlorine concentration, as chloride, with an ELCD. The VO,concentration is the sum of the carbon and chlorine content,of the sample.,1286,3.0 Definitions.,3.1 Well-mixed in the context of this method refers,to turbulent flow which results in multiple-phase waste in,effect behaving as single-phase waste due to good mixing.,4.0 Interferences. [Reserved],5.0 Safety.,5.1 Disclaimer. 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.,6.0 Equipment and Supplies.,NOTE: Mention of trade names or specific products does,not constitute endorsement by the Environmental Protection,Agency.,6.1 Sampling. The following equipment is required:,6.1.1 Sampling Tube. Flexible Teflon, 0.25 in. ID,(6.35 mm).,6.1.2 Sample Container. Borosilicate glass, 40-mL,and a Teflon-lined screw cap capable of forming an air tight,seal.,1287,6.1.3 Cooling Coil. Fabricated from 0.25 in (6.35,mm). ID 304 stainless steel tubing with a thermocouple at,the coil outlet.,6.2 Analysis. The following equipment is required.,6.2.1 Purging Apparatus. For separating the VO from,the waste sample. A schematic of the system is shown in,Figure 25D-1. The purging apparatus consists of the,following major components.,6.2.1.1 Purging Flask. A glass container to hold the,sample while it is heated and purged with dry nitrogen. The,cap of the purging flask is equipped with three fittings:,one for a purging lance (fitting with the #7 Ace-thread),one for the Teflon exit tubing (side fitting, also a,#7 Ace-thread), and a third (a 50-mm Ace-thread) to attach,the base of the purging flask as shown in Figure 25D-2. The,base of the purging flask is a 50-mm ID (2 in) cylindrical,glass tube. One end of the tube is open while the other end,is sealed. Exact dimensions are shown in Figure 25D-2.,6.2.1.2 Purging Lance. Glass tube, 6-mm OD (0.2 in),by 30 cm (12 in) long. The purging end of the tube is fitted,with a four-arm bubbler with each tip drawn to an opening,1 mm (0.04 in) in diameter. Details and exact dimensions,are shown in Figure 25D-2.,1288,6.2.1.3 Coalescing Filter. Porous fritted disc,incorporated into a container with the same dimensions as,the purging flask. The details of the design are shown in,Figure 25D-3.,6.2.1.4 Constant Temperature Chamber. A forced draft,oven capable of maintaining a uniform temperature around the,purging flask and coalescing filter of 75 + 2EC,(167 ± 3.6EF).,6.2.1.5 Three-way Valve. Manually operated,stainless steel. To introduce calibration gas into system.,6.2.1.6 Flow Controllers. Two, adjustable. One,capable of maintaining a purge gas flow rate of 6 + 0.06,L/min,(0.2 ± 0.002 ft3/min) The other capable of maintaining a,calibration gas flow rate of 1-100 mL/min,(0.00004-0.004 ft3/min).,6.2.1.7 Rotameter. For monitoring the air flow,through the purging system (0-10 L/min)(0-0.4 ft3/min).,6.2.1.8 Sample Splitters. Two heated flow,restrictors (placed inside oven or heated to 120 + 10EC (248,+ 18 EF) ). At a purge rate of 6 L/min (0.2 ft3/min), one,will supply a constant flow to the first detector (the rest,of the flow will be directed to the second sample splitter).,The second splitter will split the analytical flow between,1289,the second detector and the flow restrictor. The,approximate flow to the FID will be 40 mL/min (0.0014,ft3/min) and to the ELCD will be 15 mL/min (0.0005 ft3/min)……
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