1、Designation: D 7203 06e1Standard Test Method forScreening Trichloroethylene (TCE)-Contaminated MediaUsing a Heated Diode Sensor1This standard is issued under the fixed designation D 7203; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revis
2、ion, 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.e1NOTEEq 24 was corrected editorially in March 2007.1. Scope1.1 This test method describes procedures for screen
3、ingmedia known to contain the halogenated volatile organiccompound (HVOC), trichloroethylene (TCE). Procedure A isto be used for screening soil known to contain TCE andProcedure B is to be used for screening water known to containTCE.1.1.1 Both Procedures A and B involve measuring the TCEconcentrati
4、on in the headspace above a sample using a heateddiode sensor device. From this measurement, an estimatedconcentration of TCE in the sample can be determined. AnyTCE remaining in the sample is not measured. Any otherHVOC present in the sample will be reported as TCE.1.2 Procedure A can also be used
5、for screening the head-space above a soil suspected of containing HVOC contamina-tion to indicate the presence or absence of HVOC contamina-tion in the soil. Procedure B can also be used for screening theheadspace above a water suspected of containing HVOCcontamination to indicate the presence or ab
6、sence of HVOCcontamination in the water. For both procedures, any HVOCcontamination remaining in the soil or water is not detected bythis test method.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this
7、standard to establish appro-priate safety and health practices and determine the applica-tion of regulatory limitations prior to use.NOTE 1The diode sensor is heated to temperatures ranging betweenapproximately 600 and 1000 C (see 6.1.5) and as a result could be asource of ignition.2. Referenced Doc
8、uments2.1 ASTM Standards:2D 4547 Guide for Sampling Waste and Soils for VolatileOrganic CompoundsD 5681 Terminology for Waste and Waste Management3. Terminology3.1 DefinitionsFor definitions of terms used in this screen-ing test method, refer to Terminology D 5681.4. Summary of Test Method4.1 Proced
9、ure ATo estimate the concentration of TCE ina soil known to contain TCE contamination, a sample of thesoil is added to a glass jar having an open-top cap with aPTFE-bonded silicone septum. At the time of screening, thetemperature of the soil in the jar should be approximately 50 to120 F (10 to 49 C)
10、. The soil in the jar is shaken and allowedto settle for 10 min, so the TCE can partition into the headspaceabove the soil. After 10 min, the TCE concentration in theheadspace is measured using a heated diode sensor device,which gives a numerical voltage reading. The voltage readingfrom the device i
11、s converted to a mg/m3value of TCE in theheadspace in the container. Using this value, an estimatedconcentration of TCE in the soil in mg/Kg can be calculated.Any TCE remaining in the soil sample is not measured by thistest method. Any other HVOC present in the soil will bereported as TCE.4.1.1 To u
12、se Procedure A to screen a soil suspected ofcontaining HVOC contamination, a sample of the soil is addedto a glass jar having an open-top cap with a PTFE-bondedsilicone septum. At the time of screening, the temperature ofthe soil in the jar should be approximately 50 to 120 F (10 to49 C). The soil i
13、n the jar is shaken and allowed to settle for 10min, so the HVOC can partition into the headspace above thesoil. After 10 min, the heated diode sensor device is used to1This test method is under the jurisdiction of ASTM Committee D34 on WasteManagement and is the direct responsibility of Subcommitte
14、e D34.01.05 onScreening Methods.Current edition approved Oct. 1, 2006. Published November 2006. Originallyapproved in 2005. Last previous edition approved in 2005 as D 7203-05.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. Fo
15、r Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.screen the headspace in the container. The numerical voltagereading fr
16、om the device indicates the presence or absence ofHVOC contamination in the soil. Any HVOC contaminationremaining in the soil is not detected by this procedure.4.2 Procedure BTo estimate the concentration of TCE inwater known to contain TCE contamination, a sample of thewater is added to a glass jar
17、 having an open-top cap with aPTFE-bonded silicone septum. At the time of screening, thetemperature of the water in the jar should be approximately 50to 120 F (10 to 49 C). The water in the jar is shaken, allowedto settle for 1 min, shaken again, and allowed to settle for 1min, so the TCE can partit
18、ion into the headspace above thewater. After the sample is allowed to settle for the second time,the TCE concentration in the headspace is measured using aheated diode sensor device, which gives a numerical voltagereading. The voltage reading from the device is converted to amg/m3value of TCE in the
19、 headspace in the container. Usingthis value, an estimated concentration of TCE in the water inmg/L can be calculated. Any TCE remaining in the watersample is not measured by this procedure. Any other HVOCpresent in the water will be reported as TCE.4.2.1 To use Procedure B to screen water suspected
20、 ofcontaining HVOC contamination, a sample of the water isadded to a glass jar having an open-top cap with a PTFE-bonded silicone septum. At the time of screening, the tempera-ture of the water in the jar should be approximately 50 to 120F (10 to 49 C). The water in the jar is shaken, allowed tosett
21、le for 1 min, shaken again, and allowed to settle for 1 min,so the TCE can partition into the headspace above the water.After the sample is allowed to settle for the second time, theheated diode sensor device is used to screen the headspace inthe container. The numerical voltage reading from the dev
22、iceindicates the presence or absence of HVOC contamination inthe water. Any HVOC contamination remaining in the water isnot detected by this procedure.5. Significance and Use5.1 The heated diode sensor device used in this test methodis selective for HVOCs. Other electronegative compounds,such as alc
23、ohols, ketones, nitrates, and sulfides, may cause apositive interference with the performance of the heated diodesensor to detect HVOCs, but to do so, they must be present atmuch higher concentrations than the HVOCs.NOTE 2For volatile organic compound (VOC) screening purposes, aflame ionization dete
24、ctor (FID) selectively responds to flammable VOCs;a photoionization detector (PID) selectively responds to VOCs having adouble bond; and a heated diode sensor selectively responds to haloge-nated VOCs.5.2 This test method can be used for screening media knownto contain TCE to estimate the concentrat
25、ion of TCE in themedia. Procedure A is to be used for screening soil known tocontain TCE and Procedure B is to be used for screening waterknown to contain TCE. Both Procedures A and B involvemeasuring the TCE concentration in the headspace above asample. From this measurement, an estimated concentra
26、tion ofTCE in the sample can be determined. Any TCE remaining inthe sample is not measured by this test method. Any otherHVOC present in the sample will be reported as TCE.5.3 This test method can also be used for screening theheadspace above a soil or water suspected of containing HVOCcontamination
27、 to indicate the presence or absence of HVOCcontamination in the soil (Procedure A) or water (ProcedureB). Any HVOC contamination remaining in the sample is notdetected by this test method.5.4 Quantitation LimitThe quantitation limit of ProcedureA is dependent on the soil-to-headspace ratio in the s
28、amplecontainer and the HVOC in the soil. For a 25-g TCE-contaminated soil sample in a 250-mL container, the quantita-tion limit for TCE is 0.005 mg/Kg, based on a signal-to-noiseratio of 10. The quantitation limit of Procedure B is dependenton the water-to-headspace ratio in the sample container and
29、 theHVOC in the water. For a 25-g TCE-contaminated watersample in a 250-mL container, the quantitation limit for TCE is0.005 mg/L, based on a signal-to-noise ratio of 10.5.5 Detection LimitThe detection limit of the heateddiode sensor for TCE is 0.1 mg/m3in air, based on asignal-to-noise ratio of 2.
30、 For a 25-g TCE-contaminated soilsample in a 250-mL container, the detection limit of ProcedureA for TCE is 0.001 mg/Kg, assuming complete partitioning ofTCE into the headspace. For a 25-g TCE-contaminated watersample in a 250-mL container, the detection limit of ProcedureB for TCE is 0.001 mg/L, as
31、suming complete partitioning ofTCE into the headspace.5.6 This test method can be used to screen moist soilsamples and water samples. Water vapor does not interferewith the performance of the heated diode sensor.5.7 Hydrocarbon fuels, including fuels containing aromaticcompounds, such as gasoline, a
32、re not detected by the testmethod.6. Apparatus6.1 Procedure A and B:6.1.1 Glass Jars, 250-mL (8-oz), approximately 14 cm (512in.) tall, with open-top caps having PTFE-bonded siliconesepta.6.1.2 Scale, capable of weighing to 0.1 g.6.1.3 Thermometer, with temperature given in divisions of0.1 C6.1.4 Ba
33、rometer, such that pressure in atmospheres can bedetermined to 0.001 atm.6.1.5 Heated Diode Sensor Device, a device having a diodesensor that is heated between temperatures ranging fromapproximately 600 to 1000 C generating an alkali metal vaporstream that selectively reacts with halogens present in
34、 HVOCmolecules, creating ionized product species that cause a currentto flow between a cathode and an anode. The numerical outputfrom the sensor in volts is proportional to a microamp currentfrom the diode and ranges from 0.001 to 20 V with a resolutionof 0.001 V. The HVOC molecules in the headspace
35、 above thesample are drawn through a probe to the heated diode sensor bya pump in the device. The heated diode sensor device shouldhave a needle attached to the probe of the device so the septumin the cap of the sample jar can be pierced and the needle canbe inserted into the headspace above the sam
36、ple. This needlemust be designed to allow make-up air to enter the sample jarfrom the top so that back pressure will not build up within theD720306e12jar. Back pressure in the jar will change the air flow rate of thedevice and in turn affect the voltage reading.6.1.6 Tedlar Bags, 1 Lin volume and ha
37、ving a stainless steelvalve with a nipple fitting that can be opened and closed.6.1.7 Gas Regulators, for use with the TCE standard gascylinders (see 7.1). Each regulator should have a short length,about 114 in., of14-in. inner diameter fluoroelastomer tubingattached to the nipple fitting.6.2 Proced
38、ure A:6.2.1 Metal or Rigid Plastic Coring Tools, designed forcollecting and transferring a 25-g soil VOC sample (see GuideD 4547 and 8.1.1).7. Reagents and Materials7.1 TCE Standard Gas CylindersThese are transportablecylinders containing certified concentrations of TCE in airpressurized to about 32
39、0 psi. If the test method is being used toscreen a TCE-contaminated media to estimate the concentra-tion of TCE in the media, two concentrations of TCE arerequired. One concentration is 220 6 10 vapor part per million(ppmv) TCE in air. This is the high concentration TCE standardgas. The other concen
40、tration is 22 6 1 ppmv TCE in air, whichis the mid concentration TCE standard gas. These concentra-tions correlate with the upper and mid range of sensor responsefor the device. A 220 ppmv TCE standard gas at 25 Ccorresponds to about 890 mg/m3TCE in air at 0.75 atm ofpressure and to about 1200 mg/m3
41、TCE in air at 1 atm ofpressure. A 22 ppmv TCE standard gas at 25 C corresponds toabout 90 mg/m3TCE in air at 0.75 atm of pressure and to about120 mg/m3TCE in air at 1 atm of pressure. See Note 3 andNote 4. If the test method is being used to screen a mediasuspected of containing HVOC contamination t
42、o indicate thepresence or absence of HVOC contamination, only the highconcentration TCE standard gas, 220 6 10 ppmv TCE in air, isrequired.NOTE 3For HVOC concentrations in air that are greater than 10mg/m3, the current that is generated by the reaction between the halogenand the alkali metal vapor w
43、hen the sensor is exposed to the HVOC is afunction of the log of the concentration of the halogen in air. The log of890 is 2.9, and the log of 1200 is 3.1, showing that the log values of theseconcentrations vary only slightly. Similarly, the log of 90 is 1.9, and thelog of 120 is 2.1. These values s
44、how that the log of the TCE concentrationin air varies only slightly at different elevations (atmosphere of pressure).NOTE 4The mg/m3concentrations of the TCE in the standard gascylinders can be calculated using the ppmv concentrations of TCE in thecylinders, the atmospheric pressure, the temperatur
45、e, and Eq 5 and Eq 6,which are given in 13.6 or Eq 20 and Eq 21, which are given in 18.6.7.1.1 Transportation of the TCE gas cylinders must complywith current Department of Transportation (DOT) regulations.8. Sample Collection and Preparation8.1 Procedure A:8.1.1 Collect a soil sample of approximate
46、ly 25 g using ametal or rigid plastic coring tool. See Guide D 4547 forrecommended devices. If the sample will be stored in thecoring tool prior to screening, it should be collected using acoring tool designed for sample storage as described in GuideD 4547 and should be stored as specified in Guide
47、D 4547.8.1.2 Preweigh a 250-mL glass jar with an open-top caphaving a PTFE-bonded silicone septum. Record the mass of thejar with the cap to 60.1 g.8.1.3 Extrude the soil sample from the coring tool into thepre-weighed 250-mL glass jar and immediately seal the jarmaking sure that there are no soil p
48、articles on the sealingsurfaces.8.1.4 Weigh the jar-plus-soil sample and record the mass ofthe jar-plus-soil sample to 60.1 g.8.1.5 Determine the mass of soil added to the jar, and recordthe mass of the soil sample to 60.1 g.8.1.6 The temperature of the soil in the sample jar should beapproximately
49、50 to 120 F (10 to 49 C) prior to screening thesample using the heated diode sensor, so that HVOC partition-ing into the headspace above the sample will occur (see Note5). The sample jar should not be opened to determine the soiltemperature. The ambient temperature where the screening isto be performed should be in the range of 50 to 120 F (10 to49 C) (see Note 6), and the soil sample should be allowed tocome to approximately that temperature prior to screening(Section 12).NOTE 5The temperature at which the screening is performed mayaffect the HVOC conce
