ASTM D5953M-96(2001)
(Test Method)Standard Test Method for Determination of Non-Methane Organic Compounds (NMOC) in Ambient Air Using Cryogenic Preconcentration and Direct Flame Ionization Detection Method (Metric)
Standard Test Method for Determination of Non-Methane Organic Compounds (NMOC) in Ambient Air Using Cryogenic Preconcentration and Direct Flame Ionization Detection Method (Metric)
SCOPE
1.1 This test method covers a procedure for sampling and determining concentrations of non-methane organic compounds (NMOC) in ambient, indoor, or workplace atmospheres.
1.2 The test method describes the collection of cumulative samples in passivated stainless steel canisters and subsequent laboratory analysis.
1.2.1 This test method describes a procedure for sampling in canisters at final pressures above atmospheric pressure (referred to as pressurized sampling).
1.3 This test method employs a cryogenic trapping procedure for concentration of the NMOC prior to analysis.
1.4 This test method describes the determination of the NMOC by the simple flame ionization detector (FID), without the gas chromatographic columns and complex procedures necessary for species separation.
1.5 The range of this test method is from 20 to 10 000 ppbC (1,2). See 13.4 for procedures for lowering the range.
1.6 The test method may yield less accurate results for some halogenated or oxygenated hydrocarbons emitted from nearby sources of industrial air pollutants. This is especially true if there are high concentrations of chlorocarbons or chlorofluorocarbons present.
1.7 The values stated in SI units are regarded as the standard.
1.8 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.
General Information
Relations
Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information.
Designation:D5953M–96 (Reapproved 2001)
Standard Test Method for
Determination of Non-Methane Organic Compounds (NMOC)
in Ambient Air Using Cryogenic Preconcentration and Direct
Flame Ionization Detection Method [Metric]
This standard is issued under the fixed designation D5953M; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope responsibility of the user of this standard to establish appro-
2 priate safety and health practices and determine the applica-
1.1 This test method covers a procedure for sampling and
bility of regulatory limitations prior to use.
determining concentrations of non-methane organic com-
pounds (NMOC) in ambient, indoor, or workplace atmo-
2. Referenced Documents
spheres.
2.1 ASTM Standards:
1.2 The test method describes the collection of cumulative
D1193 Specification for Reagent Water
samples in passivated stainless steel canisters and subsequent
D1356 Terminology Relating to Sampling and Analysis of
laboratory analysis.
Atmospheres
1.2.1 Thistestmethoddescribesaprocedureforsamplingin
D1357 Practice for Planning the Sampling of the Ambient
canisters at final pressures above atmospheric pressure (re-
Atmosphere
ferred to as pressurized sampling).
D5466 Test Method for Determination of Volatile Organic
1.3 This test method employs a cryogenic trapping proce-
Chemicals inAtmospheres (Canister Sampling Methodol-
dure for concentration of the NMOC prior to analysis.
ogy)
1.4 This test method describes the determination of the
NMOC by the simple flame ionization detector (FID), without
3. Terminology
the gas chromatographic columns and complex procedures
3.1 Definitions— For definitions of terms used in this test
necessary for species separation.
method, refer to Terminology D1356.
1.5 Therangeofthistestmethodisfrom20to10000ppbC
3.2 Definitions of Terms Specific to This Standard:
(1, 2). See 13.4 for procedures for lowering the range.
3.2.1 cryogen—a refrigerant used to obtain very low tem-
1.6 Thetestmethodmayyieldlessaccurateresultsforsome
peratures in the cryogenic traps of the analytical system.
halogenated or oxygenated hydrocarbons emitted from nearby
3.2.1.1 Discussion—Liquid argon (bp−185.7°C at stan-
sources of industrial air pollutants. This is especially true if
dard pressure) is recommended for this test method. Cryogens
there are high concentrations of chlorocarbons or chlorofluo-
with lower boiling points, such as liquid nitrogen, should not
rocarbons present.
be used because of possible trapping of oxygen from the
1.7 The values stated in SI units are regarded as the
sample air, which might lead to the possibility of an explosion
standard.
or fire. In addition, methane would be trapped.
1.8 This standard does not purport to address all of the
3.2.2 dynamic calibration—calibration of an analytical sys-
safety concerns, if any, associated with its use. It is the
tem with pollutant concentrations that are generated in a
dynamic, flowing system, such as by quantitative, flow-rate
dilution of a high-concentration gas standard with zero gas.
This test method is under the jurisdiction of ASTM Committee D22 on
Sampling andAnalysis ofAtmospheres and is the direct responsibility of Subcom-
3.2.3 NMOC—non-methane organic compounds.
mittee D22.03 on Ambient Atmospheres and Source Emissions.
3.2.3.1 Discussion—Totalnon-methaneorganiccompounds
Current edition approved May 10, 1996. Published July 1996. DOI: 10.1520/
are those compounds measured by a flame ionization detector,
D5953M-96R01.
excluding methane and compounds with vapor pressure above
This test method is based on EPA Method TO-12: “Determination of Non-
−2
Methane Organic Compounds (NMOC) in Ambient Air Using Cryogenic Pre-
10 kPa, recovered from the canister.
Concentration and Direct Flame Ionization Detection (PDFID)”, Compendium of
Methods for the Determination of Toxic Organic Compounds in Ambient Air,EPA
600 4-89-017, U.S. Environmental ProtectionAgency, ResearchTriangle Park, NC, For referenced ASTM standards, visit the ASTM website, www.astm.org, or
March 1990. contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Theboldfacenumbersinparenthesesrefertothelistofreferencesattheendof Standards volume information, refer to the standard’s Document Summary page on
this standard. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D5953M–96 (2001)
3.2.4 ppm C and ppb C—concentration units of parts per because these organic compounds are primary precursors of
million and parts per billion of organic carbon as detected by atmospheric ozone and other oxidants (7, 8).
the FID. 5.2.1 The NMOC concentrations typically found at urban
3.2.4.1 Discussion—During calibration with propane, for sites may range up to 1 to 3 ppm C or higher. In order to
determinetransportofprecursorsintoanarea,measurementof
example, they are equivalent to parts per million by volume
(ppm(v))orpartsperbillionbyvolume(ppb(v)),respectively, NMOC upwind of the area may be necessary. Rural NMOC
multiplied by the number of carbon atoms in propane. concentrations originating from areas free from NMOC
sources are likely to be less than a few tenths of 1 ppm C.
5.3 Conventional test methods that depend on gas chroma-
4. Summary of Test Method (2-6)
tographyandqualitativeandquantitativespeciesevaluationare
4.1 Anairsampleisextracteddirectlyfromtheambientair,
excessively difficult and expensive to operate and maintain
collected in a precleaned sample canister and transported to a
whenspeciatedmeasurementsarenotneeded.Thetestmethod
laboratory.
described here involves a simple, cryogenic preconcentration
4.2 Afixed-volume portion of the sample air is drawn from
procedure with subsequent direct detection with the FID. The
the canister at a low flow rate through a glass-bead filled trap
testmethodissensitiveandprovidesaccuratemeasurementsof
that is cooled to approximately −186°C with liquid argon.The
ambient total NMOC concentrations where speciated data are
cryogenic trap simultaneously collects and concentrates the
not required.
NMOC using condensation, while allowing the nitrogen,
5.4 An application of the test method is the monitoring of
oxygen, methane, and other compounds with boiling points
the cleanliness of canisters.
below −186°C to pass through the trap without retention. The
5.5 Another use of the test method is the screening of
system is dynamically calibrated so that the volume of sample
canister samples prior to analysis.
passing through the trap does not have to be quantitatively
5.6 Collection of ambient air samples in pressurized canis-
measured, but must be precisely repeatable between the cali-
ters provides the following advantages:
bration and the analytical phases.
5.6.1 Convenient integration of ambient samples over a
4.3 After the fixed-volume air sample has been drawn
specific time period,
through the trap, a helium carrier gas flow is diverted to pass
5.6.2 Capabilityofremotesamplingwithsubsequentcentral
through the trap, in the opposite direction to the sample flow,
laboratory analysis,
and into an FID.When the residual air and methane have been
5.6.3 Ability to ship and store samples, if necessary,
flushed from the trap and the FID baseline restabilizes, the
5.6.4 Unattended sample collection,
cryogen is removed and the temperature of the trap is raised to
5.6.5 Analysis of samples from multiple sites with one
80 to 90°C.
analytical system,
4.4 The organic compounds previously collected in the trap
5.6.6 Collection of replicate samples for assessment of
revolatilize due to the increase in temperature and are carried
measurement precision, and
into the FID, resulting in a response peak or peaks from the
5.6.7 Specific hydrocarbon analysis can be performed with
FID. The area of the peak or peaks is integrated, and the
the same sample system.
integrated value is translated to concentration units using a
previously obtained calibration curve relating integrated peak
6. Interferences
areas with known concentrations of propane.
6.1 In laboratory evaluations, moisture in the sample has
4.5 The cryogenic trap simultaneously concentrates the
been found to cause a positive shift in the FID baseline. The
NMOC while separating and removing the methane from air
effect of this shift is minimized by carefully selecting the
samples. The technique is thus direct reading using FID for
integration termination point and adjusting the baseline used
NMOC and, because of the concentration step, it is more
for calculating the area of the NMOC peaks.
sensitive than conventional continuous NMOC analyzers.
6.2 With helium as a carrier gas, FID response is quite
4.6 The sample is injected into the hydrogen-rich flame of
uniform for most hydrocarbon compounds, but the response
the FID, where the organic vapors burn, producing ionized
can vary considerably for other types of organic compounds.
molecular fragments. The resulting ion fragments are then
collected and detected. Because this test method employs a
7. Apparatus
helium carrier gas, the detector response is nearly identical for
many hydrocarbon compounds of interest. Thus, the historical
7.1 Sample Collection System,(Fig. 1).
short-coming of varying FID response to aromatic, olefinic, 7.1.1 Sample Canister(s), stainless steel, Summa -polished
and paraffinic hydrocarbons is minimized. The FID is much
vessel(s) of 4 to 6 Lcapacity, used for automatic collection of
lesssensitivetomostorganiccompoundscontainingfunctional integrated field air samples.
groups such as carbonyls, alcohols, halocarbons, etc.
7.1.1.1 Mark each canister with a unique identification
number stamped on its frame.
5. Significance and Use 7.1.2 Sample Pump, stainless steel, metal bellows type.
5.1 Many industrial processes require determination of
NMOC in the atmosphere.
5.2 Accurate measurements of ambient concentrations of
The Summa process is a trademark of Molectrics, Inc., 4000 E. 89th St.,
NMOC are important for the control of photochemical smog Cleveland, OH 44105.
D5953M–96 (2001)
7.2.9 Isothermal Oven, for heating canisters, not shown in
Fig. 2.
7.3 Analytical System,(Fig. 3).
7.3.1 FID System, includes flow controls for the FID fuel
andcombustionair,temperaturecontrolfortheFID,andsignal
processing electronics. Set the FID combustion air, hydrogen,
and helium carrier flow rates as defined by the manufacturer’s
instructions to obtain an adequate FID response while main-
taining a stable flame throughout all phases of the analytical
cycle.
7.3.2 Data Reduction Device, such as a computer, equipped
withdataacquisitionhardwareandsoftwareandalaserprinter,
or an electronic integrator, with chart recorder, capable of
integrating the area of one or more FID response peaks and
calculating peak area corrected for baseline drift.
7.3.2.1 If a separate integrator and chart recorder are used,
FIG. 1 Sample System for Automatic Collection of Integrated Air
exercise care to ensure that these components do not interfere
Samples
with each other electrically or electronically.
7.3.2.2 Range selector controls on both the integrator and
7.1.2.1 Ensure that the pump is free of leaks, and uncon-
the FID analyzer may not provide accurate range ratios, so
taminated by oil or organic compounds.
prepare individual calibration curves for each range.
7.1.2.2 Shock mount the pump to minimize vibration.
7.3.2.3 The integrator must be capable of marking the
7.1.3 Pressure Gage, 0 to 210 kPa (0 to 30 psig).
beginning and ending of peaks, constructing the appropriate
7.1.4 Solenoid Valve, controls the sample flow to the canis-
baseline between the start and end of the integration period,
ter with negligible temperature rise.
and calculating the peak area.
7.1.5 Flow Control Device, mass flowmeter, critical orifice,
7.3.3 Cryogenic Trap, constructed from a single piece of
or short capillary to maintain the sample flow over the
chromatographic-grade stainless steel tubing (3 mm outside
sampling period.
diameter, 2 mm inside diameter), as shown in Fig. 4.
7.1.6 Particulate Matter Filter, inert in-line filter, 2µ m or
7.3.3.1 Pack the central portion of the trap (70 to 100 mm)
less, or other suitable filter, used to filter the air sample.
with silanized 180 to 250 µm (60/80 mesh) glass beads, with
7.1.7 Auxiliary Vacuum Pump or Blower, draws sample air
small silanized glass wool plugs, to retain the beads.
through the sample inlet line to reduce inlet residence time to
7.3.3.2 Thearmsofthetrapmustbeofsuchlengthtopermit
no greater than 10 s.
the beaded portion of the trap to be submerged below the level
7.1.7.1 Shock mount the pump to minimize vibration.
of cryogen in the Dewar flask.
7.1.8 Timer, programmable, and electrically connected to
7.3.3.3 Connectthetrapdirectlytothesix-portvalve(7.3.4)
thesolenoidvalve(7.1.4)andpumps(7.1.2and7.1.7),capable
of controlling the pumps and the solenoid valve. to minimize the line length between the trap (7.3.3) and the
FID (7.3.1).
7.1.9 Sample Inlet Line, transports the sample air into the
samplesystem,consistingofstainlesssteeltubingcomponents.
7.3.3.4 MountthetraptoallowclearancesotheDewarflask
7.2 Sample Canister Cleaning System,(Fig. 2).
maybeappliedandwithdrawntofacilitatecoolingandheating
7.2.1 Vacuum Pump, capable of evacuating sample canis-
the trap (see 7.3.12).
ter(s) to an absolute pressure of# 2 Pa (15 µm Hg).
7.3.4 Six-Port Valve— Locate the six-port valve and as
7.2.2 Manifold, stainless steel manifold with connections
much of the interconnecting tubing as practical inside an oven
for simultaneously cleaning several canisters.
or otherwise heat it to 80 to 90°C to minimize wall losses or
7.2.3 Shut-off Valve(s), nine required.
adsorption/desorption in the connecting tubing. All lines must
7.2.4 Pressure Gage, 0 to 350 kPa (0 to 50 psig)–monitors
be as short as practical.
zero-air pressure.
7.3.5 Multistage Pressure Regulators (3required),standard
7.2.5 Cryogenic Trap (2 required), U-shaped open tubular
two-stage, stainless steel diaphragm regulators with pressure
trap cooled with liquid argon used to prevent contamination
gages, for helium, air, and hydrogen cylinders.
from back diffusion of oil from vacuum pump, and providing
7.3.6 Auxilliary Flow or Pressure Regulators (2 required),
clean, zero-air to the sample canister(s).
tomaintainconstantflowrates,within1mL/minforthehelium
7.2.6 Vacuum Gage, capable of measuring vacuum in the
carrier and the hydrogen.
manifoldtoanabsolutepressureof15Pa(0.1mmHg)orless,
7.3.7 F
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.