ASTM D8230-19

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D8230 − 19
Standard Test Method for
Measurement of Volatile Silicon-Containing Compounds in a
Gaseous Fuel Sample Using Gas Chromatography with
Spectroscopic Detection
This standard is issued under the fixed designation D8230; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 3. Terminology
3.1 Definitions—For definitions of general gaseous fuel
1.1 This test method is primarily for gas-phase siloxane
terms used in this test method, refer to Terminology D4150.
compounds present in biogas and other gaseous fuel samples at
ppmv and high ppbv concentrations. It may also be applicable
3.2 Definitions of Terms Specific to This Standard:
to low ppbv concentrations under certain circumstances.
3.2.1 analytical sequence, n—describes how and the order
that field and QC samples in an analytical batch are analyzed.
1.2 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
3.2.2 calibration standard (ICAL), n—a mixture of an
responsibility of the user of this standard to establish appro-
analyte at a known concentration prepared from a primary
priate safety, health, and environmental practices and deter-
stock.
mine the applicability of regulatory limitations prior to use.
3.2.2.1 Discussion—A calibration standard is analyzed at
1.3 This international standard was developed in accor-
varying concentrations and used to calibrate the response of the
dance with internationally recognized principles on standard-
measurement system with respect to analyte concentration.
ization established in the Decision on Principles for the
3.2.3 Continuing Calibration Verification (CCV) Standard,
Development of International Standards, Guides and Recom-
n—a solution (or set of solutions) of known analyte concen-
mendations issued by the World Trade Organization Technical
tration used to verify freedom from excessive instrumental
Barriers to Trade (TBT) Committee.
drift; the concentration is to be near the mid-range of a linear
calibration curve.
2. Referenced Documents
3.2.4 gas phase sample, n—a direct-injection sample that
2.1 ASTM Standards:
has been collected in a device such as a summa canister or
D4150 Terminology Relating to Gaseous Fuels
Tedlar bag.
2.2 Government Documents: 3.2.5 Initial (or Independent) Calibration Verification (ICV)
Compendium Method TO-15 Determination of Volatile Or-
Standard, n—a solution (or set of solutions) of known analyte
ganic Compounds (VOCs) in Air Collected in Specially- concentration used to verify calibration standard levels; the
Prepared Canisters and Analyzed by Gas
concentration of analyte is to be near the mid-range of the
Chromatography/Mass Spectrometry (GC/MS) calibration curve that is made from a stock solution having a
NIOSH Manual of Analytical Methods (NMAM) - 4th different manufacturer or manufacturer lot identification than
the calibration standards.
Edition Development and Evaluation of Methods
3.2.6 integration filter, n—a mathematical operation per-
formed on an absorbance spectrum for the purpose of convert-
ing the spectrum to a single-valued response suitable for
This test method is under the jurisdiction of ASTM Committee D03 on Gaseous
Fuels and is the direct responsibility of Subcommittee D03.06.01 on Analysis of
representation in a two-dimensional chromatogram plot.
Major Constituents by Gas Chromatography.
3.2.7 internal standard, n—a non-analyte element, present
Current edition approved June 1, 2019. Published August 2019. DOI: 10.1520/
D8230-19. in all calibration, blank, and sample solutions, the signal from
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
which is used to correct for non-spectral interference or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
improve analytical precision.
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website.
3.2.8 laboratory control sample (LCS), n—a laboratory
Available from U.S. Environmental Protection Agency, 109 T.W. Alexander
control sample is an analyte-free matrix to which a known
Drive, Durham, NC 27709, https://www.epa.gov.
quantity of analyte is added.
Available from The National Institute for Occupational Safety and Health
(NIOSH), https://www.cdc.gov. 3.2.8.1 Discussion—The LCS is subjected to the same
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D8230 − 19
processing as field samples and is carried through the entire 6.1.5 Gas Sampling Bags—Less volatile siloxanes may
analytical process. The percent recovery of the analytes in the adhere to the inner surface of sampling bags resulting in low
LCS is used to assess method performance. Certain programs analytic recoveries for these components.
and projects require analysis of a duplicate laboratory control
6.2 Sorbent Tubes
sample (LCSD).
6.2.1 High Humidity Matrices—Sample streams at elevated
3.2.9 library reference spectrum, n—an absorbance spec-
temperatures that contain high concentrations of water vapor
trum representation of a molecular species stored in a library
may condense water at the inlet end of sorbent tubes. Con-
database and used for identification of a compound/compound
densed water may cause clogging or irregular sample flow
class or deconvolution of multiple co-eluting compounds.
through sorbent tubes.
6.2.2 Solvent Effect—Standards prepared in a solvent may
3.2.10 method blank (MB), n—an analyte-free matrix which
show chromatographic distortions and retention time variation
is processed and carried through the entire analytical process.
due to the high solvent vapor concentrations.
It is used to evaluate the process for contamination from the
6.2.3 Sample Preparation—Interferences due to contami-
laboratory.
nants in sorbents, solvents, reagents, glassware, and other
3.2.11 siloxanes, n—a functional group in organosilicon
sample processing hardware can result in artifacts or elevated
chemical family with the Si–O–Si linkage.
baselines, or both, in detector profiles. All of these materials
3.2.12 sorbent tube sample, n—a sample that contains solid
must be routinely demonstrated to be free from interferences
sorbent and requires extraction prior to analysis.
under the conditions of analysis. All glassware associated with
this method must be scrupulously cleaned to avoid contamina-
4. Summary of Test Method
tion.
4.1 This test method is used to determine the gas-phase
6.3 Instrument Interferences
concentrations of selected volatile silicon compounds in the
6.3.1 Matrix Effect—Samples with a high hydrocarbon con-
ppbv to ppmv concentration range in biogas and other gaseous
tent may attenuate the spectral signal; hence, it may be
fuel samples where gas chromatography is used to speciate the
necessary to use the lowest volume possible to meet detection
target analytes. A spectroscopic detection method is then used
limit requirements when analyzing some biogases. Each spec-
to detect and quantify the silicon compounds. Volatile silicon
tral detector should be evaluated for their optimal analyte range
compounds analyzed according to this method include trim-
and hydrocarbon interference.
ethylsilanol, hexamethyldisiloxane, hexamethylcyclotrisi-
6.3.2 Gas Chromatograph
loxane, octamethyltrisiloxane, octamethylcyclotetrasi-
6.3.2.1 Column Bleed—Films made of dimethyl polysi-
loxane, decamethyltetrasiloxane, decamethylcyclopentasilox-
loxane can break down to give column bleed, at higher
ane, dodecamethylpentasiloxane, and dodecamethylcyclohexasil-
temperatures. Using a lower bleed column such as diphenyl
oxane. Additional compounds may be analyzed provided the
dimethyl polysiloxane or 1,4-bis(dimethylsiloxy)phenylene di-
data satisfies data quality objectives specified in this standard.
methyl polysiloxane reduces column bleed.
5. Significance and Use
6.3.3 Mass Spectrometer (MS)
6.3.3.1 Tune the MS as needed in order to obtain consistent
5.1 Silica generated from the combustion of gases contain-
and acceptable performance.
ing siloxane compounds can damage internal combustion
6.3.3.2 MS source cleaning and other maintenance should
engines or microturbine blades, reduce heat transfer efficiency
be performed as needed depending on the performance of the
of landfill gas and biogas equipment, and poison catalytic
unit.
oxidizers that are used to control regulated volatile organic
6.3.4 Inductively Coupled Mass Spectrometer (ICP-MS)
compound emissions. The ability to analyze siloxanes in
6.3.4.1 Siloxanes are stable and generally do not react
biologically derived fuel gases and other gaseous fuel matrices
quickly with most sample matrices. The mass abundance ratio
is highly desirable in order to assess the initial siloxane content
of silicon is unique and easily identifiable.
and the efficacy of gas pretreatment measures.
6.3.4.2 Spectroscopic Interferences—Polyatomic interfer-
6. General Interferences
ences are caused by polyatomic ions that are formed from ions
6.1 Gas Phase Samples that originate in the sample matrix, reagents used for
6.1.1 Highly Reactive Matrices—Certain highly reactive preparation, and plasma gases. Interfering ions carry a mass to
matrices have the capability to damage the passivated surface charge ratio that is identical to that of the analyte ion.
Polyatomic interferences are minimized with the use of
of a sample canister.
6.1.2 High Humidity Matrices—Sample streams at elevated collision/reaction gas in a collision/reaction cell. Silicon has
isotopes with masses 28, 29, and 30. Table 1 shows possible
temperatures that contain high concentrations of water vapor
may condense water in a sample canister. Condensed water interferences with these masses. The isotopes in bold face
indicate that it is the most abundant isotope for that element.
may absorb or react, or both, with some target analytes.
6.1.3 Valve Lubrication—Any equipment utilizing a valve 6.3.5 Atomic Emissions Detector (AED)
may have lubrication that contributes unknown quantities of 6.3.5.1 Silicon emissions are measured at a wavelength of
siloxanes depending on brand and construction materials. 251.6 nm or 221.7 nm. High concentrations of carbon from
6.1.4 Stainless Steel Canisters—Less volatile siloxanes may co-eluting hydrocarbons can result in a false positive interfer-
adhere to stainless steel or nickel surfaces. ence for siloxane at its measured wavelength. Typically the
D8230 − 19
TABLE 1 Polyatomic Interferences with Silicon in ICP-MS
7.2.3 Detectors—Many different types of detectors may be
Silicon Interference used for identification and detection of siloxanes and other
Isotope
volatile compounds; this includes but is not limited to: mass
28 14 +, 12 16 +
Si N2 C O
spectrometer (MS), inductively coupled plasma-mass spec-
29 14 1 +, 14 15 +, 12 16 1 +, 12 17 +, 13 16 + , 28 1 + trometer (ICP-MS), or atomic emissions detector (AED). As
Si N2 H N N C O H C O C O Si H
long as the detector meets the performance criteria in this
30 14 1 +, 14 15 1 +, 15 +, 14 16 +, 12 18 +, 13 17 +,
Si N2 H2 N N H N2 N O C O C O
method for each compound of interest it may be utilized.
13 16 1 +, 12 17 1 +, 12 16 1 +, 29 1 +
C O H C O H C O H2 Si H
8. Reagents and Materials
selectivity of silicon to carbon is near 30 000:1. Carbon
8.1 Reagents for Sample Preparation
concentration can be monitored simultaneously with silicon by
8.1.1 Samples collected in canisters may be pressurized
measuring the carbon wavelength at 247.9 nm (for 251.6 nm
with dry UHP nitrogen. Most biogas samples are humid; in the
Si) or 193.1 nm (for 221.7 nm Si). This data, along with
case of dry samples, humidity may be added to improve
viewing the raw spectral data in the 251.6 nm range, can be
recoveries of siloxanes from canisters.
used to identify carbon interference. Silicon emits as a ‘triplet’
8.2 Instrumentation Gases—Gas requirements depend on
with minor emission bands at 250.7 nm and 252.9 nm in
instrumentation being used, but use of UHP grade gases is
addition to the measured emission band at 251.6 nm. If using
suggested.
221.7 nm, a similar ‘triplet’ is observed with additional bands
8.3 Internal Standards—The internal standard mixture used
at 220.8 nm and 221.2 nm. These ‘triplets’ form a unique
‘fingerprint’ signal for silicon. When a high concentration of for siloxanes analysis depends on the instrumentation being
used. For example, GC-MS instruments will use a VOC
carbon is present, a series of minor emission bands will appear
analysis internal standard mixture, such that it does not
in addition to the strong emission at 247.9 nm or 193.1 nm.
One of these minor emission bands can overlap with the interfere with the target analytes and is not routinely prevalent
in the matrix. Such examples include bromofluorbenzene,
measured silicon emission and result in a false positive.
Therefore a positive signal without the silicon triplet diethylene glycol dimethyl ether. If using a GC-ICP-MS, a
mixture of brominated compounds is preferable for use as
‘fingerprint,’ in addition to a strong carbon emission at
247.9 nm or 193.1 nm, suggests carbon interference. internal standards.
8.4 Siloxanes Standards
7. Apparatus
8.4.1 It is desirable that two sources of siloxanes standards
7.1 Sample Collection Apparatus
are utilized for calibration and QA purposes. The standards
7.1.1 Passivated Stainless Steel Canisters—Clean, evacu-
may be purchased in cylinders or neat form, or prepared in the
ated stainless steel containers whose surfaces have been
laboratory.
passivated with a fused-silica lining. May be used to collect
8.4.2 Liquid Phase Neat Standards—Laboratory-prepared
grab samples, or attached to flow regulator for collection of
standards will require the purchase of neat standards. Purities
composite samples.
range from 97.0 % to 99.5 %.
7.1.2 Gas Sampling Bags—Clean sample bags made of
8.4.3 Liquid phase standards are prepared and stored in a
non-reactive and non-absorbing material, such as Tedlar, which
refrigerator at or below 4 °C, and protected from light.
includes a sampling valve with septum. Note that for some
8.4.4 Purchased standards are replaced after 5 years or as
detectors, the valve must be free of silicone grease. High
recommended by the manufacturer.
molecular weight siloxanes may have adsorption issues with
8.4.5 Stock standards may be prepared in either n-Hexane
these type sample containers. These sample containers may be
(99.5 % or equivalent), or methylene chloride (gas chromatog-
used to collect grab samples, or attached to flow regulator and
raphy grade, or equivalent).
pump, if necessary, for collection of composite samples.
8.4.6 Gas Phase Static Dilution
7.1.3 Sorbent Tubes—Hydrophobic carbon-based sorbents
8.4.6.1 n-Hexane, (99.5 %), or equivalent. “Hexane” con-
such as Anasorb 747 sorbent have been successfully interfaced
taining a mixture of hexane isomers should not be used as some
in a 500 mg ⁄250 mg dual bed, packed into an SPE reservoir,
isomers may co-elute with target analytes and interfere with the
outfitted with two frits (NMAM - 4th Edition). Alternative
analyte quantitation masses.
sorbents may be used provided they meet the desorption
8.4.6.2 Inject an aliquot of the liquid stock standard into a
efficiency study criteria specified in Appendix X1.
canister while pressurizing with nitrogen. The injection point
7.2 Instrumentation
must be heated to avoid condensation and adsorption loss of
7.2.1 Preconcentration System—Preconcentration may be
siloxanes at the injection site. Continue to dilute with nitrogen
used to remove water vapor and matrix gases from the gas
until the desired concentration has been achieved.
sample. Method parameters are optimized to separate sample
matrices and for maximum analyte recoveries.
9. Hazards
7.2.2 Gas Chromatograph—A gas chromatograph with or
without cryogenic focus will be interfaced to a spectral 9.1 Standard procedures for the safe handling of
detection system. A low to mid-polarity column will give flammables, compressed gases, and cryogenic fluids should be
separation of siloxanes and other volatile silicon compounds. followed.
D8230 − 19
9.2 Safety considerations specific to apparatus or instrumen- 11.2 Column Conditioning—Initial conditioning of the
tation fluids should be followed. chromatographic column is required prior to use. The column
should be conditioned with a continuous flow of helium
10. Sampling and Sample Preparation (UHP/ZERO 99.999 % purity or better) and GC temperature
ramp programmed from 40 °C to 250 °C at a rate of five
10.1 Section A: Gas Phase Sample Collection
degrees per minute. The column should then be held at 250 °C
10.1.1 Tedlar Bags—If sampling from a positive pressure
for 2 h.
source, the bag can be filled to 60 to 75 % of capacity. If
sampling from ambient or sub ambient sources, a lung sampler
11.3 Instrument Performance Check—Performance checks
or related type of vacuum chamber can be used to fill the bag.
should be completed before initial startup and after every 24 h
10.1.2 Sample Handling and Preservation
period of operation.
10.1.2.1 Summa Canisters—If necessary, pressurize the can-
11.3.1 GC-MS—The GC-MS system must meet the mass
ister to the desired pressure (maximum 40 psig, or 2828 Torr).
spectra ion abundance criteria for bromofluorobenzene. Refer
10.1.2.2 Tedlar Bags—Studies have shown siloxane recov-
to instrument manufacturer tuning criteria.
5,6,7
eries to quickly degrade in Tedlar Bags. It is recommended
11.3.2 GC-ICP-MS—The system is optimized manually
that samples are analyzed within 72 h of sampling (Compen-
based on the instrument response to 10-ppm xenon in helium.
dium Method TO-15). The valve of the bag should be inspected
Torch position and lens voltages are adjusted to give the
for possible leaks, and it is recommended that bags are stored
maximum signal for Xe-128 and Xe-132. The pulse/analog
in a dark, cool environment.
(P/A) factor must be tuned after the sensitivity tune. The
10.2 Section B: Sorbent Tube Sample Collection
quadropole and electromultiplier detector are tuned if there has
10.2.1 The recommended sampling rate is 0.2 L ⁄min to
been an obvious change in sensitivity or when a new calibra-
1.0 L ⁄min for a total sample volume of 30 L. Different
tion will be prepared. This is accomplished by performing the
sampling volumes may be used depending on sampling appli-
E/M tuning and Resolution/Axis tuning. The P/A factor is set
cation. If samples are taken from a positive pressure source,
to 1 during E/M tuning, so the P/A factor must be tuned
tubes can be connected to a rotameter or dry test meter on the
directly after the E/M tuning is performed.
outlet end to measure flow. If the samples are taken at ambient
11.3.3 GC-AED—Alignment of the AED is automated by
or negative pressure, a sample pump may be used.
the instrument upon startup. Realignment should be performed
10.3 Sample Handling and Preservation
after every 24 h period of operation.
10.3.1 Thermal preservation is not required for the SPE
11.4 Initial Calibration Curve
cartridges prior to shipment to the field, after field sampling, in
11.4.1 Percent Relative Standard Deviation of the Relative
transit to the laboratory or once received in the laboratory. The
Response Factor (%RSD RRF)—The %RSD RRF for each
samples, extracts, media, and standards must all be stored
siloxane component in the initial calibration must be less than
separately to minimize contamination. The hold time should
30 % for the calibration to be considered valid for that
not exceed 14 days. The hold time from extraction to analysis
component. The %RSD RRF is calculated for each siloxane
should not exceed 30 days.
component in the calibration according to Eq 13.
10.3.2 Sample Extraction Prior to Analysis—In a hood,
11.4.2 Correlation Coeffıcient—Alternatively, if the RRF
remove the end caps. Decant the two sections of sorbent into
two separate clean vials. Add 3 mL of methylene chloride to cannot meet the 30 % criteria, the absolute value of the
correlation coefficient must be calculated for each compound.
each vial and agitate vials. Allow the vials to sit for a minimum
of 30 min with periodic agitation. Take an aliquot of the This value must be at least 0.990 to be valid.
extract, transfer it to a 2 mL autosampler vial (or equivalent),
11.4.3 To determine the validity of the continuing calibra-
and add internal standard.
tion curve, a mid-level CCV is analyzed with each batch of 10
samples, or daily. If the calibration check-standard fails to meet
11. Equipment Preparation
QA requirements, another CCV is run to verify the failure. If
the CCV fails QA on the second run, then a new multi-point
11.1 Place all equipment in service and in accordance with
calibration curve must be prepared or other corrective action
the manufacturer’s instructions. Since there are many options,
taken and documented, or both.
as long as the equipment utilized meets the quality control
performance criteria as listed in this m
...