ASTM D7363-13A(2021)e1

Standard Test Method for Determination of Parent and Alkyl Polycyclic Aromatics in Sediment Pore Water Using Solid-Phase Microextraction and Gas Chromatography/Mass Spectrometry in Selected Ion Monitoring Mode

SIGNIFICANCE AND USE
5.1 This method directly determines the concentrations of dissolved PAH concentrations in environmental sediment pore water samples. The method is important from an environmental regulatory perspective because it can achieve the analytical sensitivities to meet the goals of the USEPA narcosis model for protecting benthic organisms in PAH contaminated sediments. Regulatory methods using solvent extraction have not achieved the wide calibration ranges from nanograms to milligrams per litre and the required levels of detection in the nanogram-per-litre range. In addition, conventional solvent extraction methods require large aliquot volumes (litre or larger), use of large volumes of organic solvents, and filtration to generate the pore water. This approach entails the storage and processing of large volumes of sediment samples and loss of low molecular weight PAHs in the filtration and solvent evaporation steps.  
5.2 This method can be used to determine nanogram to milligram per litre PAH concentrations in pore water. Small volumes of pore water are required for SPME extraction, only 1.5 mL per determination and virtually no solvent extraction waste is generated.
SCOPE
1.1 The U.S. Environmental Protection Agency (USEPA) narcosis model for benthic organisms in sediments contaminated with polycyclic aromatic hydrocarbons (PAHs) is based on the concentrations of dissolved PAHs in the interstitial water or “pore water” in sediment. This test method covers the separation of pore water from PAH-impacted sediment samples, the removal of colloids, and the subsequent measurement of dissolved concentrations of the required 10 parent PAHs and 14 groups of alkylated daughter PAHs in the pore water samples. The “24 PAHs” are determined using solid-phase microextraction (SPME) followed by Gas Chromatography/Mass Spectrometry (GC/MS) analysis in selected ion monitoring (SIM) mode. Isotopically labeled analogs of the target compounds are introduced prior to the extraction, and are used as quantification references.  
1.2 Lower molecular weight PAHs are more water soluble than higher molecular weight PAHs. Therefore, USEPA-regulated PAH concentrations in pore water samples vary widely due to differing saturation water solubilities that range from 0.2 µg/L for indeno[1,2,3-cd]pyrene to 31 000 µg/L for naphthalene. This method can accommodate the measurement of microgram per litre concentrations for low molecular weight PAHs and nanogram per litre concentrations for high molecular weight PAHs.  
1.3 The USEPA narcosis model predicts toxicity to benthic organisms if the sum of the toxic units (ΣTUc) calculated for all “34 PAHs” measured in a pore water sample is greater than or equal to 1. For this reason, the performance limit required for the individual PAH measurements was defined as the concentration of an individual PAH that would yield 1/34 of a toxic unit (TU). However, the focus of this method is the 10 parent PAHs and 14 groups of alkylated PAHs (Table 1) that contribute 95 % of the toxic units based on the analysis of 120 background and impacted sediment pore water samples.3 The primary reasons for eliminating the rest of the 5-6 ring parent PAHs are: (1) these PAHs contribute insignificantly to the pore water TU, and (2) these PAHs exhibit extremely low saturation solubilities that will make the detection of these compounds difficult in pore water. This method can achieve the required detection limits, which range from approximately 0.01 µg/L, for high molecular weight PAHs, to approximately 3 µg/L for low molecular weight PAHs.  
1.4 The test method may also be applied to the determination of additional PAH compounds (for example, 5- and 6-ring PAHs as described in Hawthorne et al.).4 However, it is the responsibility of the user of this standard to establish the validity of the test method for the determination of PAHs other than those referenced in 1.1 and Table 1.  
1.5 The values stated in ...

General Information

• Status: Published
• Publication Date: 31-Oct-2021
• ICS: 13.080.10 - Chemical characteristics of soils
• Technical Committee: D19 - Water
• Drafting Committee: D19.06 - Methods for Analysis for Organic Substances in Water

Relations

• Refers: ASTM E178-16 - Standard Practice for Dealing With Outlying Observations
• Effective Date: 01-Jun-2016
• Refers: ASTM D2777-12 - Standard Practice for Determination of Precision and Bias of Applicable Test Methods of Committee D19 on Water
• Effective Date: 15-Jun-2012
• Refers: ASTM D3370-10 - Standard Practices for Sampling Water from Closed Conduits
• Effective Date: 01-Dec-2010
• Refers: ASTM E178-08 - Standard Practice for Dealing With Outlying Observations
• Effective Date: 01-Oct-2008
• Refers: ASTM D3370-08 - Standard Practices for Sampling Water from Closed Conduits
• Effective Date: 01-Oct-2008
• Refers: ASTM D2777-08 - Standard Practice for Determination of Precision and Bias of Applicable Test Methods of Committee D19 on Water
• Effective Date: 15-Jan-2008
• Refers: ASTM D3370-07 - Standard Practices for Sampling Water from Closed Conduits
• Effective Date: 01-Dec-2007
• Refers: ASTM D2777-06 - Standard Practice for Determination of Precision and Bias of Applicable Test Methods of Committee D19 on Water
• Effective Date: 15-Aug-2006
• Refers: ASTM D1193-06 - Standard Specification for Reagent Water
• Effective Date: 01-Mar-2006
• Refers: ASTM D2777-03 - Standard Practice for Determination of Precision and Bias of Applicable Methods of Committee D-19 on Water
• Effective Date: 10-Aug-2003
• Refers: ASTM E178-02 - Standard Practice for Dealing With Outlying Observations
• Effective Date: 10-May-2002
• Refers: ASTM D3370-95a(1999)e1 - Standard Practices for Sampling Water from Closed Conduits
• Effective Date: 10-Jun-1999
• Refers: ASTM D1193-99e1 - Standard Specification for Reagent Water
• Effective Date: 10-Feb-1999
• Refers: ASTM D1193-99 - Standard Specification for Reagent Water
• Effective Date: 10-Feb-1999
• Refers: ASTM D1192-98 - Standard Guide for Equipment for Sampling Water and Steam in Closed Conduits (Withdrawn 2003)
• Effective Date: 10-Jul-1998

Overview

The ASTM D7363-13A(2021)e1 standard, developed by ASTM International, provides a robust test method for the determination of parent and alkyl polycyclic aromatic hydrocarbons (PAHs) in sediment pore water. Utilizing solid-phase microextraction (SPME) and gas chromatography/mass spectrometry (GC/MS) in selected ion monitoring (SIM) mode, this method achieves the sensitivity and calibration range required for effective environmental monitoring and regulatory compliance. By directly measuring dissolved PAH concentrations, the standard plays a critical role in supporting the U.S. Environmental Protection Agency (USEPA) narcosis model for evaluating toxicity risk to benthic organisms in PAH-contaminated sediments.

Key Topics

• Direct Measurement of PAHs: Offers precise quantification of both parent and alkylated PAHs in small volumes (as little as 1.5 mL) of sediment pore water without extensive solvent extraction or large sample sizes.
• Solid-Phase Microextraction (SPME): Utilizes SPME coupled with GC/MS to minimize solvent waste and sample handling losses, particularly of low-molecular-weight PAHs.
• High Sensitivity and Wide Calibration Range: Achieves detection levels from nanograms to milligrams per liter, meeting the analytical needs for both low and high molecular weight PAHs.
• Regulatory Relevance: Aligns with the USEPA narcosis model's requirements, supporting environmental risk assessment and sediment remediation decision-making.
• Target Compounds: Focuses on 10 parent PAHs and 14 groups of alkylated PAHs, which account for the majority of toxicity in sediment pore water, while allowing adaptation for additional PAH analytes if needed.
• Toxic Unit Calculation: Provides data critical for calculating toxic units (ΣTUc), essential for predicting the impact of contaminated sediments on benthic organisms.

Applications

The ASTM D7363-13A(2021)e1 standard is widely applicable to:

• Environmental Compliance and Monitoring: Essential for regulatory agencies and environmental labs monitoring sediment quality and compliance with sediment toxicity guidelines.
• Ecological Risk Assessment: Facilitates reliable assessment of the potential risks PAH-contaminated sediments pose to benthic organisms in aquatic ecosystems.
• Remediation Effectiveness Evaluation: Supports before-and-after analysis of sediment remediation projects to confirm reductions in bioavailable PAHs.
• Research on Contaminated Sediments: Enables academic and industrial researchers to measure freely dissolved, bioavailable PAH concentrations using state-of-the-art SPME and GC/MS techniques.
• Regulatory Reporting: Provides standardized procedures for test reporting in support of USEPA, state, and international sediment assessment frameworks.

Related Standards

• ASTM D1193: Specification for reagent water required for analytical and laboratory use.
• ASTM D3370: Practices for sampling water from flowing process streams, pertinent for sediment and pore water sampling protocols.
• ASTM D2777: Practice for determination of precision and bias in water analysis, relevant for validating laboratory performance.
• USEPA Guidelines and Narcosis Model: The method is specifically designed to fulfill the data quality objectives outlined by the USEPA for sediment toxicity assessment.
• NIST SRM 1991: Provides certified reference materials essential for calibration and validation in PAH measurement.

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Keywords: ASTM D7363, polycyclic aromatic hydrocarbons, PAHs, sediment pore water, solid-phase microextraction, SPME, gas chromatography, mass spectrometry, GC/MS, selected ion monitoring, SIM, environmental compliance, sediment toxicity, USEPA narcosis model, alkylated PAHs, environmental risk assessment, benthic organisms, sediment remediation.

Standards Content (Sample)

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.
´1
Designation: D7363 − 13a (Reapproved 2021)
Standard Test Method for
Determination of Parent and Alkyl Polycyclic Aromatics in
Sediment Pore Water Using Solid-Phase Microextraction
and Gas Chromatography/Mass Spectrometry in Selected
1,2
Ion Monitoring Mode
This standard is issued under the fixed designation D7363; 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.
ε NOTE—Reapproved with editorial changes in November 2021.
1. Scope 1.3 The USEPA narcosis model predicts toxicity to benthic
organismsifthesumofthetoxicunits(ΣTU )calculatedforall
c
1.1 The U.S. Environmental Protection Agency (USEPA)
“34 PAHs” measured in a pore water sample is greater than or
narcosis model for benthic organisms in sediments contami-
equal to 1. For this reason, the performance limit required for
nated with polycyclic aromatic hydrocarbons (PAHs) is based
the individual PAH measurements was defined as the concen-
on the concentrations of dissolved PAHs in the interstitial
trationofanindividualPAHthatwouldyield ⁄34ofatoxicunit
water or “pore water” in sediment.This test method covers the
(TU).However,thefocusofthismethodisthe10parentPAHs
separation of pore water from PAH-impacted sediment
and14groupsofalkylatedPAHs(Table1)thatcontribute95%
samples, the removal of colloids, and the subsequent measure-
of the toxic units based on the analysis of 120 background and
ment of dissolved concentrations of the required 10 parent
impacted sediment pore water samples. The primary reasons
PAHs and 14 groups of alkylated daughter PAHs in the pore
for eliminating the rest of the 5-6 ring parent PAHs are: (1)
water samples. The “24 PAHs” are determined using solid-
thesePAHscontributeinsignificantlytotheporewaterTU,and
phase microextraction (SPME) followed by Gas
(2) these PAHs exhibit extremely low saturation solubilities
Chromatography/Mass Spectrometry (GC/MS) analysis in se-
that will make the detection of these compounds difficult in
lected ion monitoring (SIM) mode. Isotopically labeled ana-
pore water. This method can achieve the required detection
logs of the target compounds are introduced prior to the
limits, which range from approximately 0.01 µg/L, for high
extraction, and are used as quantification references.
molecular weight PAHs, to approximately 3 µg/L for low
1.2 Lower molecular weight PAHs are more water soluble
molecular weight PAHs.
than higher molecular weight PAHs. Therefore, USEPA-
1.4 The test method may also be applied to the determina-
regulated PAH concentrations in pore water samples vary
tion of additional PAH compounds (for example, 5- and 6-ring
widely due to differing saturation water solubilities that range
PAHs as described in Hawthorne et al.). However, it is the
from 0.2 µg/L for indeno[1,2,3-cd]pyrene to 31000 µg/L for
responsibility of the user of this standard to establish the
naphthalene. This method can accommodate the measurement
validityofthetestmethodforthedeterminationofPAHsother
ofmicrogramperlitreconcentrationsforlowmolecularweight
than those referenced in 1.1 and Table 1.
PAHsandnanogramperlitreconcentrationsforhighmolecular
weight PAHs. 1.5 The values stated in SI units are to be regarded as
standard. No other units of measurement are included in this
standard.
This test method is under the jurisdiction ofASTM Committee D19 on Water 1.6 This standard does not purport to address all of the
andisthedirectresponsibilityofSubcommitteeD19.06onMethodsforAnalysisfor
safety concerns, if any, associated with its use. It is the
Organic Substances in Water.
Current edition approved Nov. 1, 2021. Published December 2021. Originally
approved in 2007. Last previous edition approved in 2013 as D7363 – 13a. DOI:
10.1520/D7363-13AR21E01. Hawthorne, S. B., Grabanski, C. B., and Miller, D. J., “Measured Partitioning
Standard methods under the jurisdiction of ASTM Committee D19 may be Coefficients for Parent and Algae Polycyclic Aromatic Hydrocarbons in 114
publishedforalimitedtimepreliminarytothecompletionoffullcollaborativestudy Historically Contaminated Sediments: Part I, Koc Values,” Environmental Toxicol-
validation. Such standards are deemed to have met all other D19 qualifying ogy and Chemistry, Vol 25, 2006, pp. 2901–2911.
requirements but have not completed the required validation studies to fully Hawthorne, S. B., Grabanski, C. B., Miller, D. J., and Kreitinger, J. P., “Solid
characterize the performance of the test method across multiple laboratories and Phase Microextraction Measurement of Parent and Akyl Polycyclic Aromatic
matrices. Preliminary publication is done to make current technology accessible to Hydrocarbons in Milliliter Sediment Pore Water Samples and Determination of
users of standards, and to solicit additional input from the user community. K Values,” Environmental Science Technology, Vol 39, 2005, pp. 2795–2803.
DOC
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
´1
D7363 − 13a (2021)
A
TABLE 1 Target PAHs, Toxic Unit Factors and Performance Limits
Added d-PAH d-PAH Internal Conc. for One Basis for
Performance Limit
Analyte Internal Std. for Toxic Unit, Performance
(ng/mL)
B
Standard Calculation C , (ng/mL) Limit
tu
Naphthalene A A 193.47 5.69 B
2-Methylnaphthalene B 81.69 2.40 B
1-Methylnaphthalene B B 81.69 2.40 B
C2-Naphthalenes A 30.24 0.89 B
C3-Naphthalenes A 11.10 0.33 B
C4-Naphthalenes A 4.05 0.12 C
Acenaphthylene C 308.85 9.03 B
Acenaphthene C C 55.85 1.64 B
Fluorene D D 39.30 1.16 B
C1-Fluorenes D 13.99 0.41 B
C2-Fluorenes D 5.30 0.16 B
C3-Fluorenes D 1.92 0.06 S
Phenanthrene E E 19.13 0.56 B
Anthracene E 20.72 0.61 B
C1-Phenanthrenes/Anthracenes E 7.44 0.22 B
C2-Phenanthrenes/Anthracenes E 3.20 0.09 B
C3-Phenanthrenes/Anthracenes E 1.26 0.04 B
C4-Phenanthrenes/Anthracenes E 0.56 0.02 S
Fluoranthene F 7.11 0.21 B
Pyrene F F 10.11 0.30 B
C1-Fluoranthenes/Pyrenes F 4.89 0.14 C
Benz[a]anthracene G 2.23 0.066 B
Chrysene G G 2.04 0.060 B
C1-Chrysenes/Benz[a]anthracenes G 0.86 0.025 C
A
From Hawthorne, S. B., Grabanski, C. B., Miller, D. J., and Kreitinger, J. P., “Solid Phase Microextraction Measurement of Parent and Alkyl Polycyclic Aromatic
Hydrocarbons in Milliliter Sediment Pore Water Samples and Determination of K Values,” Environmental Science Technology, Vol 39, 2005, pp. 2795–2803.
DOC
B
Performance limits were determined as 3 times the background concentrations from the SPME fiber based on the analysis of water blanks (“B”), the lowest calibration
standard which consistently yielded a signal to noise ratio of at least 3:1 (“C”), or (for when no calibration standard was available) for the lowest concentrations consistently
found in pore water samples with a signal to noise ratio of at least 3:1 (“S”). Detection limits for alkyl PAHs are based on a single isomer.
responsibility of the user of this standard to establish appro- 3. Terminology
priate safety, health, and environmental practices and deter-
3.1 Definitions:
mine the applicability of regulatory limitations prior to use.
3.1.1 calibration standard, n—a solution prepared from a
For specific hazard statements, refer to Section 9.
secondary standard, stock solution, or both, and used to
1.7 This international standard was developed in accor-
calibrate the response of the instrument with respect to analyte
dance with internationally recognized principles on standard-
concentration.
ization established in the Decision on Principles for the
3.1.2 calibration verification standard (VER), n—the mid-
Development of International Standards, Guides and Recom-
pointcalibrationstandard(CS3)thatisanalyzeddailytoverify
mendations issued by the World Trade Organization Technical
the initial calibration.
Barriers to Trade (TBT) Committee.
3.1.3 CS1, CS2, CS3, CS4, n—shorthand notation for cali-
2. Referenced Documents
bration standards.
2.1 ASTM Standards:
3.1.4 data acquisition parameters, n—parameters affecting
D1192Guide for Equipment for Sampling Water and Steam
the scanning operation and conversion of the analytical signal
in Closed Conduits (Withdrawn 2003)
to digitized data files.
D1193Specification for Reagent Water
3.1.4.1 Discussion—These include the configuration of the
D2777Practice for Determination of Precision and Bias of
ADC circuitry, the ion dwell time, the MID cycle time, and
Applicable Test Methods of Committee D19 on Water
acquisition modes set up for the method. Examples of acqui-
D3370Practices for Sampling Water from Flowing Process
sition modes for the HP5973 include SIM mode, and Low
Streams
Mass Resolution Mode
E178Practice for Dealing With Outlying Observations
3.1.5 performance limit, n—performance limit for an indi-
vidual PAH is defined as the concentration of an individual
PAH that would yield ⁄34 of a toxic unit.
3.1.5.1 Discussion—For a performance limit of an indi-
vidual PAH, refer to Table 1 (see 4.6).
3.1.6 deuterated PAH (d-PAH), n—polycyclic aromatic hy-
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
drocarbons in which deuterium atoms are substituted for all
Standards volume information, refer to the standard’s Document Summary page on
hydrogens (that is, perdeuterated).
the ASTM website.
3.1.6.1 Discussion—In this method, d-PAHs are used as
The last approved version of this historical standard is referenced on
www.astm.org. internal standards.
´1
D7363 − 13a (2021)
3.1.7 GC, n—gas chromatograph or gas chromatography. each ion. This results in greater instrument sensitivity for the
selectedions.Spectralscanningandlibrarysearching,usedfor
3.1.8 HRGC, n—high resolution GC.
tentatively identified compounds, are not supported in this
3.1.9 LRMS, n—low resolution MS.
mode.
3.1.10 internal standards, n—isotopically labeled analogs
3.1.20 signal-to-noise ratio, n—the ratio of the mass spec-
(d-PAHs) of the target analytes that are added to every sample,
trometerresponseofaGCpeaktothebackgroundnoisesignal.
blank, quality control spike sample, and calibration solution.
3.1.21 NIST, n—National Institute of Standards and Tech-
3.1.10.1 Discussion—They are added to the water samples
nology.
immediately after completing the flocculation step and trans-
3.1.22 SRM, n—Standard reference material obtained from
ferring the water aliquot to the autosampler vial, and immedi-
ately after adding the calibration PAH solution to water NIST.
calibrationstandards,butbeforeSPMEextraction.Theinternal
standards are used to calculate the concentration of the target 4. Summary of Test Method
analytes or estimated detection limits.
4.1 Either the use of an autosampler, or a manual approach
3.1.11 laboratory blank, n—see method blank.
can be used to perform the SPME extraction and the subse-
quent injection of collected analytes into the GC/MS. An
3.1.12 method blank, n—an aliquot of reagent water that is
autosampler (Leap Technologies Combi-Pal or equivalent) is
extracted and analyzed along with the samples to monitor for
much preferred over the manual method because: (1) the
laboratory contamination.
autosampleryieldslowerandmorereproducibleblanks, (2)the
3.1.12.1 Discussion—Blanks should consistently meet con-
manual method requires the use of a stir bar that can cause
centrations at or less than one-third of the performance limits
sample cross-contamination, (3) the manual method is highly
Table1.Alternatively,ifthePAH
forindividualPAHsstatedin
labor-intensive and requires multiple timed manipulations per
concentrations calculated from the water blank immediately
analysisleadingtooperatorfatigueandresultanterrors,and (4)
preceding the test samples are <20% of the test sample
theautosamplerreducesthetechniciantimerequiredtoprepare
concentrations, the blank is acceptable.
samples for a 24-h run sequence to approximately 3 h, while
3.1.13 low calibration level (LCL), n—thelevelatwhichthe
the manual method requires 24-h operator attendance.
entire analytical system must give a recognizable signal and
Therefore,themethodproceduresarewrittenassumingtheuse
acceptable calibration point for the analyte.
of an autosampler, with modifications to the autosampler
3.1.13.1 Discussion—Itisequivalenttotheconcentrationof
procedures listed for the manual method.
the lowest calibration standard assuming that all method-
specified sample weights, volumes, and cleanup procedures
AUTOSAMPLER METHOD
have been employed.
4.2 Pore Water Separation and Preparation—The pore
3.1.14 high or upper calibration level (UCL), n—the con-
water is separated from wet sediment samples by centrifuga-
centration or mass of analyte in the sample that corresponds to
tion and supernatant collection. Colloids are removed from the
the highest calibration level in the initial calibration.
separated pore water samples by flocculation with aluminum
3.1.14.1 Discussion—Itisequivalenttotheconcentrationof
potassiumsulfate(alum)andsodiumhydroxideasdescribedin
the highest calibration standard, assuming that all method-
Hawthorne et al. A second flocculation and centrifugation,
specified sample weights, volumes, and cleanup procedures
followed by supernatant collection completes the colloid re-
have been employed.
moval.The prepared pore water samples are then split into the
requirednumberofreplicatealiquots(1.5mLeach)andplaced
3.1.15 MS, n—mass spectrometer or mass spectrometry.
into silanized glass autosampler vials. The 7 perdeuterated
3.1.16 PAH, n—polycyclic aromatic hydrocarbon, or
PAH internal standards (d-PAHs) are then added immediately.
alternately, polynuclear aromatic hydrocarbon.
All of the water preparation steps beginning with the centrifu-
3.1.17 percent difference (%D), n—the difference between
gation and ending with the addition of d-PAH internal stan-
the analyzed concentration and expected concentration, ex-
dards should be conducted continuously and in the minimum
pressed as a percentage of the expected concentration.
amount of time possible.
4.2.1 TheSPMEfibershouldbecleanedatthebeginningof
3.1.18 relative response factor (RRF), n—the empirically
determined ratio between the area ratio (analyte to internal each sampling set (and after very contaminated samples) for 1
h by placing in the cleaning chamber under helium flow at
standard) and the unit mass of analyte in the calibration
standard (area ratio/ng) for available alkyl PAHs in a given 320°C. This can conveniently be performed while the pore
waters are being prepared.
homolog and their parent PAH.
3.1.19 selected ion monitoring (SIM), n—a mode of opera- 4.3 Solid-Phase Microextraction—The SPME extraction of
tion for the mass spectrometer in which specific ions are
the pore water samples is performed using a commercially
monitored. available (available from Sigma-Aldrich, formerly Supleco, or
3.1.19.1 Discussion—This mode of operation differs from equivalent) 7 µm film thickness polydimethylsiloxane
the full scan mode, in which the MS acquires all ions within a (PDMS)-coated fused silica fiber for 30 min while the water
range. Because the spectrometer is monitoring fewer ions in sample is mixed by the precession of the autosampler mixing
the SIM mode, more acquisition (dwell) time is possible for chamber at a rate of 250 revolutions per minute. The target
´1
D7363 − 13a (2021)
A, B
TABLE 2 PAH concentrations in SRM 1991
PAHs and d-PAH internal standards adsorb to the nonpolar
Mass Fraction, µg/g
PDMS phase at equivalent rates. The use of the d-PAHs (that
Naphthalene 26.0 ± 1.1
is,isotopicdilution)toquantitatethetargetPAHscompensates
2-Methylnaphthalene 11.7 ± 0.5
for variations in equilibrium partitioning and kinetics.
1-Methylnaphthalene 8.02 ± 0.32
C2-Naphthalenes 21.3 ± 2.8
4.4 GC/MS SIM Analysis—Following the sorption period,
C3-Naphthalenes 29.5 ± 1.5
the SPME fiber is immediately desorbed in a GC/MS injection
C4-Naphthalenes 33.8 ± 4.7
C
Acenaphthylene 0.5
port in the splitless mode at 320°C for 5 min. The GC/MS
Acenaphthene 6.83 ± 0.89
system specified uses a 60 m narrow-bore (250 µm ID)
Fluorene 3.8 ± 1.0
HP5-MS or equivalent capillary column to achieve high
C1-Fluorenes 5.62 ± 0.27
C2-Fluorenes 7.20 ± 0.39
resolution for PAHs. Following the 5 min desorption period,
C3-Fluorenes 5.16 ± 0.50
the SPME fiber is inserted into the cleaning port and addition-
Phenanthrene 12.1 ± 0.6
allycleanedfor15minunderheliumflowat320°C.Attheend
Anthracene 3.33 ± 0.43
C1-Phenanthrenes/Anthracenes 10.7 ± 3.2
of the cleaning period, sorption of the next water sample is
C2-Phenanthrenes/Anthracenes 15.5 ± 1.9
begun.
C3-Phenanthrenes/Anthracenes 15.1 ± 0.2
C4-Phenanthrenes/Anthracenes 10.2 ± 1.1
4.5 The mass spectrometer is operated in the SIM mode for
Fluoranthene 3.54 ± 0.39
the molecular ions of the target PAHs and d-PAHs to achieve
Pyrene 5.91 ± 0.16
C1-Fluoranthenes/Pyrenes 6.86 ± 0.54
low limits of detection. Analyte concentrations are quantified
Benz[a]anthracene 1.79 ± 0.21
by three methods:
Chrysene 1.32 ± 0.15
4.5.1 PAHsforwhichanexactdeuteratedanalogisincluded
C1-Chrysenes/ 1.54 ± 0.46
Benz[a]anthracenes
in the internal standard mix are quantified by isotope dilution.
A
Single compound concentrations are reported for parent PAHs and the two
4.5.2 Parent PAHs (that is, unsubstituted PAHs) for which
methylnaphthalene isomers in the NIST SRM 1991 certificate. All other alkyl-PAH
an exact deuterated analog is not included in the internal
concentrations are reported as the total for each isomeric group. Concentration
values should be revised if updated values are reported by NIST. Mass fraction
standardmixarequantifiedbyreferencetoadeuteratedanalog
(µg/g) units can be converted to mass/volume units based on the SRM solution
of a PAH with the same number of rings as the analyte.
density of 1.31 reported in the NIST SRM 1991 certificate.
B
4.5.3 Alkyl PAHs are quantified using the experimentally
95 % confidence intervals are reported as described in the NIST SRM 1991
certificate.
determined relative response factors based on each lab’s
C
Acenaphthylene is reported as possibly unstable in the NIST SRM 1991
analysis of SRM 1991 and the concentration values listed in
certificate. However, this does not affect D7363 results since acenaphthylene
Table 2. Relative response factors for the alkyl PAHs are in
calibration is based on calibration solutions prepared with pure parent PAHs.
reference to their parent PAH.
4.6 Conversion of Quantified Concentration to Toxic
Units—The USEPAnarcosis model predicts toxicity to benthic
length is exposed to the water sample, but not so low that the
organisms if the sum of the toxic units calculated for all “34
fiber comes into contact with the stir bar or that the metal
PAHs” measured in a pore water sample is greater than or
needle sheath contacts the water.All time sequences should be
equal to 1. For this reason, the performance limits required for
the same as specified for the autosampler method.Aspare GC
the individual PAH measurements were defined as the concen-
split/splitless injection port at 320°C and under helium flow
tration of an individual PAH that would yield ⁄34 of a toxic
can be used for the 15-min cleaning step between samples as
unit. See Table 1.This distribution reflects the relative concen-
wellasfortheinitial1-hcleaningstepatthebeginningofeach
trations of PAHs expected to be found in pore water because
experimental day. Other procedures are the same as for the
the lower molecular weight PAHs are more soluble and have
autosampler method.
lower organic carbon partition coefficients (Koc), and reflects
the lower partitioning of lower molecular weight PAHs to the
5. Significance and Use
receptor organism since they have smaller octanol/water coef-
ficients (Kow). The performance limits are essentially bench-
5.1 This method directly determines the concentrations of
marks to ensure that the adequate sensitivity is achieved to
dissolved PAH concentrations in environmental sediment pore
predict toxicity.
water samples. The method is important from an environmen-
tal regulatory perspective because it can achieve the analytical
MANUAL METHOD
sensitivitiestomeetthegoalsoftheUSEPAnarcosismodelfor
4.7 Alternate Procedures for Manual Method—Samples are protecting benthic organisms in PAH contaminated sediments.
prepared as for the autosampler method, except that a small Regulatorymethodsusingsolventextractionhavenotachieved
polytetrafluoroethylene (PTFE)-coated stir bar is placed in the the wide calibration ranges from nanograms to milligrams per
silanizedautosamplervialpriortoaddingthewaterandd-PAH litre and the required levels of detection in the nanogram-per-
internal standard solution. A new stir bar should be used for litre range. In addition, conventional solvent extraction meth-
each sample, calibration standard, and blank to avoid cross- ods require large aliquot volumes (litre or larger), use of large
contamination caused by carryover on the stir bar. To perform volumes of organic solvents, and filtration to generate the pore
theSPMEstep,thevialissetonastirplateandthestirringrate water.Thisapproachentailsthestorageandprocessingoflarge
adjusted so that no large vortex is formed. The SPME fiber volumesofsedimentsamplesandlossoflowmolecularweight
should be inserted into the water so that the entire 1-cm active PAHs in the filtration and solvent evaporation steps.
´1
D7363 − 13a (2021)
5.2 This method can be used to determine nanogram to 7.5 Magnetic Stir Plate (for manual method only).
milligram per litre PAH concentrations in pore water. Small
7.6 SPME Holder Stand (for manual method only) or
volumes of pore water are required for SPME extraction, only
GC/MS Autosampler, capable of SPME extraction and injec-
1.5 mL per determination and virtually no solvent extraction
tion.
waste is generated.
7.7 Cleaning Port, capable of purging SPME fibers in a
6. Interferences helium-swept atmosphere at 320°C.
6.1 Non-target hydrocarbons can cause peaks on selected 7.8 GC/MS Analysis:
ion current profiles (SICPs) intended for other PAHs. Pattern
7.8.1 Gas Chromatographshallhavesplit/splitlessinjection
recognition must be employed for identifying interfering port for capillary column, temperature program with isother-
peaks, and peak series that should not be considered for the
mal hold.
homolog or target PAH under consideration. Analysts should
7.8.2 GC Column, 60 m × 0.25 mm ID × 0.25 µm film
beintimatelyfamiliarwithbothparentandalkylPAHanalyses
thickness HP5-MS or equivalent.
in complex environmental samples. Representative samples
7.8.3 Inlet Liner, 2 mm ID silanized glass.
having higher PAH concentrations should periodically be
7.8.4 GC Inlet, 320°C, splitless mode.
analyzed by full scan GC/MS so that pattern recognition of
7.8.5 Oven Program—Isothermal5minholdat40°C.Ramp
alkyl PAHs (and interfering species) can be verified by their
at 50°C/min to 110°C, followed by a temperature ramp of
full mass spectra. This procedure is particularly important for
12°C/min to 320°C (hold for 10 min).
newer operators.
7.8.6 Mass Spectrometer—Electron impact ionization with
6.2 Solvents, reagents, glassware and other sample process- the ionization energy optimized for best instrument sensitivity
ing hardware may yield discrete artifacts or elevated baselines (typically 70 eV), stability and signal to noise ratio. Shall be
that may cause misinterpretation of the chromatographic data. capable of repetitively selectively monitoring at least 12 m/z
All of these materials must be demonstrated to be free from during a period of approximately 1 s and shall meet all
interferences under the conditions of analysis by performing manufacturers’ specifications.
laboratory method blanks. Analysts should avoid using PVC 7.8.7 GC/MS Interface—The mass spectrometer (MS) shall
gloves, powdered gloves, or gloves with measurable levels of
be interfaced to the GC such that the end of the capillary
phthalates. column terminates within 1 cm of the ion source but does not
NOTE 1—The use of high purity reagents and solvents helps minimize
intercept the electron or ion beam.
interference problems.
7.8.8 Data System, capable of collecting, recording, and
storing MS data.
7. Apparatus
7.1 Centrifuge, capable of sustaining 1000 g with cups for
8. Reagents and Materials
securing 40 mL and 20 mL vials.
8.1 Purity of Reagents—Reagent grade chemicals must be
7.2 SPME Fiber Holder, compatible with 7-µm SPME fiber
used in all tests. Unless otherwise indicated, it is intended that
and compatible with either the autosampler or the manual
method.
7.3 SPME Fibers, 7-µm thick polydimethylsiloxane
(PDMS) coating or equivalent.
7.4 PTFE Coated Stir Bars (Stir Fleas), of a size effective
forstirring1.5mLwaterwithoutvortexing(formanualmethod
only).
TABLE 3 Primary Material Hazards
A
Material Hazards Exposure Limit Signs and Symptoms of Exposure
Alum (Aluminum Potassium Sulfate) Irritant 2 mg/M May cause skin irritation, especially under repeated or prolonged contact, or when
TWA moisture is present. May irritate or burn the eyes. Dust or mist inhalation at levels
above the TLV may cause irritation to the respiratory tract. May irritate the
gastrointestional tract.
Acetone Flammable 1000 ppm-TWA Inhalation of vapors irritates the respiratory tract. May cause coughing, dizziness,
dullness, and headache.
Dichloromethane (DCM) Carcinogen, 25 ppm-TWA, Causes irritation to respiratory tract. Has a strong narcotic effect with symptoms of
Irritant 125 ppm-STEL mental confusion, light-headedness, fatigue, nausea, vomiting and headache. Causes
irritation, redness and pain to the skin and eyes. Prolonged contact can cause burns.
Liquid degreases the skin. May be absorbed through skin.
Sodium Hydroxide Corrosive 2 mg/M Causes skin irritation, chemical burns, permanent injury or scarring, and blindness.
TWA Vinegar is a mild acid that will neutralize lye if it were to make contact with the skin.
Harmful if inhaled or ingested. Causes Sore throat, cough labored breathing,
shortness of breath, and abdominal pain. Symptoms may be delayed.
A
Exposure limit refers to the OSHA regulatory exposure limit.
´1
D7363 − 13a (2021)
all reagents shall conform to the specifications of the Commit- the MSDS for each material before using it for the first time or
tee onAnalytical Reagents of theAmerican Chemical Society, when there are major changes to the MSDS.
where such specifications are available.
10. Sampling and Sample Preservation
8.2 Purity of Water—Unless otherwise indicated, references
to water shall be understood to mean reagent water that meets
10.1 Collect the sediment sample in accordance with Prac-
the purity specifications of Type I or Type II water, presented tices D3370 and Specification D1192, as applicable.
in Specification D1193.
10.2 Prior to shipment, the samples should be mixed well.
8.3 40 mL Vials, with PTFE-lined caps.
Sieve the slurry of sediment and site water through a 2-mm
screen to remove debris. If the sieved slurry is to be stored or
8.4 20 mL Vials, with PTFE-lined caps.
shippedbeforeuse,storein250mLto1LjarswithPTFE-lined
8.5 Silanized 2.0 mL Autosampler Vials.
lids. Great care must be taken to clean the lid of the jar before
8.6 Internal Standard Stock Solution—A dichloromethane
capping with the lid to avoid leakage of the water during
solutionofd-PAHinternalstandardsusedforpreparingspiking shipment.
solutions by dilution into acetone (see 12.2).
10.3 Ship in an ice chest with adequate ice to maintain 0 to
8.7 Internal Standard Spiking Solution—A dilution of the
6°C. Store at the laboratory in the dark at 0 to 6°C.
internalstandardstocksolutioninacetoneusedtospiked-PAH
internal standards into all sample, calibration, and blank water
11. Preparation of Apparatus
vials.
11.1 Set up the GC system using the following parameters.
8.8 Calibration Stock Solution—A dichloromethane solu-
11.1.1 GC Column Agilent HP-5MS column (0.25 µm film
tion of PAHs used for preparing calibration standards (see
thickness, 0.25 mm ID) or equivalent.
12.2).
11.1.2 Inlet liner 2-mm ID silanized glass.
11.1.3 GC Inlet 320°C, splitless mode.
8.9 Calibration Spiking Solutions—A series of solutions
11.1.4 Oven Program—Isothermal 5 min hold at 40°C.
preparedbydilutingthecalibrationstocksolutionwithacetone
Ramp at 50°C/min to 110°C, followed by a temperature ramp
(see 12.2).
of 12°C/min to 320°C. (Hold for 10 min.)
8.10 Calibration Standards—Prepared by adding internal
MS Quad Temperature 150°C, maximum 200°C
standardandcalibrationspikingsolutionsinreagentwater(see
MS Source Temperature 230°C, maximum 250°C
12.2).
11.1.5 Set up SIM Groups to monitor the quantitation and
8.11 Acetone.
internal standard ions. Optimal exact masses should be deter-
8.12 Dichloromethane (DCM). mined by monitoring 0.1 mass units near the nominal molecu-
lar weight of each PAH to determine the exact mass which
8.13 Sodium Hydroxide (NaOH). Use a 1 molar solution in
gives the best signal to noise ratio. Example masses are shown
reagent grade water.
in Table 4. Optimal exact masses should be determined before
8.14 Aluminum Potassium Sulfate Dodecahydrate—Alum,
the initial use of the method, when major maintenance is
(AlK(SO ) ·12H O).
4 2 2
performed on the mass spectrometer (for example, ion source
8.15 Alum Solution—10 wt. % (wt/vol) of alum in reagent cleaning), and if the laboratory is having trouble meeting
grade water. detectionlimitrequirements.Eachiondwelltimeshouldbeset
at 25 ms. Twelve ions are monitored in each group.
8.16 SRM 1991—Obtained from NIST, Gaithersburg, MD,
USA.
NOTE 2—Some ions (for example, m/z 184.1 for C4 naphthalenes) are
included in two ion groups to ensure that the target peaks are adequately
monitored. Table 4 should be used with the chromatograms in Appendix
9. Hazards
X1 to aid the analyst in setting proper retention time windows and
9.1 The effluents of sample splitters for the gas chromato-
recognition of target and contaminant peaks, especially for the alkyl
clusters.
graph and roughing pumps on the mass spectrometer must be
vented to the laboratory hood exhaust system or must pass
12. Calibration
through an activated charcoal filter.
9.2 Primary Materials Used—Table 3 contains a summary 12.1 Determine the absolute and relative retention times of
the first and last characteristic peak in each homolog with the
of the primary hazards listed in the MSDS. A complete list of
materials used in the method can be found in the reagents and aid of the examples in Appendix X1.
12.1.1 Set up a SIM program with the necessary ions to
materials section. Practitioners must review the information in
acquire all the alkyl-PAH homologs using the ion groups
shown in Table 4 and 25 ms dwell time per ion.
12.1.2 Update the expected retention times in the method
ACS Reagent Chemicals, Specifications and Procedures for Reagents and
Standard-Grade Reference Materials, American Chemical Society, Washington,
section of the quantitation software using the d-PAH internal
DC. For suggestions on the testing of reagents not listed by theAmerican Chemical
standards of previous runs as relative retention time markers
Society, see Analar Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset,
andtherepresentativechromatogramsinAppendixX1.Assure
U.K., and the United States Pharmacopeia and National Formulary, U.S. Pharma-
copeial Convention, Inc. (USPC), Rockville, MD. that the SIM windows for the homologs are set to at least 8 s
´1
D7363 − 13a (2021)
TABLE 4 SIM Ion Groups and Typical Retention Time Windows
before the first, and 30 s after the last characteristic peaks to
assure coverage of the elution range.
NOTE 1—Retention times must be verified by the user.
SIM Target
12.2 Analyze Initial Calibration:
Retention Time (min)
Analyte Ion m/z
A 12.2.1 Prepare stock solutions of PAHs and internal stan-
Start Stop
Group (typically)
dard stock solutions of d-PAHs at approximately the concen-
Naphthalene 1 128.1 7 17
2-Methylnaphthalene 1 142.1 7 17 trations shown in Table 5.These concentrations were based on
1-Methylnaphthalene 1 142.1 7 17
the PAH distributions previously determined in 120 sediment
C2-Naphthalenes 1 156.1 7 17
pore water samples. Stocks are prepared in DCM. Spiking
C3-Naphthalenes 1 170.1 7 17
C4-Naphthalenes 1,2 184.1 7 21 solutions are prepared by dilution of intermediate stocks in
Acenaphthylene 1 152.2 7 17
acetone. For calibration solutions, spiking solutions are added
Acenaphthene 1 154.2 7 17
to reagent water.
Fluorene 1 166.2 7 17
C1-Fluorenes 2 180.2 17 21
12.2.1.1 Prepare calibration standard spiking solutions.
C2-Fluorenes 2 194.2 17 21
These are prepared by diluting the stock in acetone to give the
C3-Fluorenes 2,3 208.2 17 25
calibration solution concentrations (CS1–CS4), as described
Phenanthrene 2 178.2 17 21
Anthracene 2 178.2 17 21
below:
C1-Phenanthrenes/ 2 192.2 17 21
(1)For CS1, take 5 µL stock to 100 mL in acetone.
Anthracenes
(2)For CS2 take 50 µL to 100 mL in acetone.
C2-Phenanthrenes/ 2,3 206.2 17 30
Anthracenes
(3)For CS3, take 25 µL to 10 mL in acetone.
C3-Phenanthrenes/ 2,3 220.2 17 30
(4)For CS4, take 100 µL to 10 mL in acetone.
Anthracenes
C4-Phenanthrenes/ 3 234.2 21 30 12.2.1.2 Spike4µLofeachcalibrationsolutioninto1.5mL
Anthracenes
of reagent water to give a calibration series with the low
Fluoranthene 2,3 202.2 17 30
calibration limits (LCLs) and upper calibration limits (UCLs)
Pyrene 2,3 202.2 17 30
C1-Fluoranthenes/ 3 216.2 21 30
shown in Table 5. Spike 10 µL of internal standard spiking
pyrenes
solution at the concentrations shown in Table 5 into each vial.
Benz[a]anthracene 3 228.2 21 30
12.2.1.3 Extract and analyze the calibration series.
Chrysene 3 228.2 21 30
C1-Chrysenes 3 242.2 21 30
(1)Extract and analyze two water blank solutions.
d-PAH Internal Standards
(2)Extract and analyze the water calibration solutions, as
Naphthalene-d8 1 136.1 7 17
describedin13.4and13.5.BeginwiththeCS1-spikedsample,
1-Methylnaphthalene-d10 1 152.1 7 17
Acenaphthene-d10 1 164.2 7 17
followed by sequentially more concentrated calibration stan-
Fluorene-d10 1 176.2 7 17
dards. Follow by two water blanks.
Phenanthrene-d10 2 188.2 17 21
Fluoranthene-d10 2,3 212.2 17 30
12.2.1.4 Calculate the performance parameters for the cali-
Pyrene-d10 2,3 212.2 17 30
bration.
Chrysene-d12 3 240.2 21 30
(1)Generate ion chromatograms for the optimal exact
A
Exact masses (to the 0.1 amu) should be optimized for each GC/MS instrument
masses (examples are listed in Table 4) that encompass the
as described in Section 11.1.5.
expectedretentionwindowsofthetargetanalytes.Integratethe
selected ion current profiles of the quantitation ions shown in
TABLE 5 Initial Calibration Standard Series
LCL UCL
DCM
Analyte Stock Conc. CS1 CS2 CS3 CS4
mg/mL
ng/1.5 mL ng/1.5 mL ng/1.5 mL ng/1.5 mL
Naphthalene 41.5 8.3 83 415 1660
1-Methylnaphthalene 23.9 4.78 47.8 239 956
2-Methylnaphthalene 20.4 4.08 40.8 204. 817
Acenaphthylene 9.02 1.80 18.0 90.2 361
Acenaphthene 11.0 2.20 22.0 110 440
Fluorene 7.55 1.51 15.1 75.5 302
Anthracene 0.60 0.120 1.20 6.0 24.0
Phenanthrene 5.5 1.1 11 55 220
Fluoranthene 2.11 0.422 4.22 21.1 84.4
Pyrene 1.8 0.36 3.60 18.0 72.0
Benz[a]anthracene 0.08 0.016 0.16 0.8 3.2
Chrysene 0.03 0.006 0.06 0.3 1.2
Deuterated Analogs of Stock Solution CS1 CS2 ng CS3 CS4
Mix A Compounds µg/mL ng/1.5 mL ng/1.5 mL ng/1.5 mL ng/1.5 mL
Naphthalene-d8 5 50.0 50.0 50.0 50.0
1-Methylnaphthalene-d10 6 60.0 60.0 60.0 60.0
Acenaphthene-d10 1.23 12.3 12.3 12.3 12.3
Fluorene-d10 1.2 12.0 12.0 12.0 12.0
Phenanthrene-d10 0.96 9.6 9.6 9.6 9.6
Pyrene-d10 0.84 8.4 8.4 8.4 8.4
Chrysene-d12 0.033 0.33 0.33 0.33 0.33
´1
D7363 − 13a (2021)
the table. Integration of alkyl clusters should be as the total calibration. If the root cause can be traced to an abnormal
area of the cluster integrated from the baseline before the first disruption of an individual acquisition (for example, injector
malfunction) repeat the individual analysis and recalculate the
peak in the cluster to the baseline after the last peak in the
cluster peaks. Cluster peaks should never be integrated using percent relative standard deviation. If the calibration is
acceptable, document the problem and proceed; otherwise
the valley-to-valley method. The peak areas of non-target
repeat the initial calibration.
peaks (see Appendix X1) must be removed from the alkyl
cluster peak area before any calculation. 12.3.1 Because of the large range of calibration concentra-
tions required, the wide range of water solubilities of the
(2)Calculate the area ratio (analyte peak area divided by
individual PAHs, and the desire to require only one stock
internal standard peak area) per unit mass of analyte, using the
calibration solution, some PAHs may only have a three point
area of the appropriate internal standard listed in Table 1.
linear calibration curve that meets the above criteria. This is
Quantitativecalculationsarebasedonacomparisonofthearea
most likely to occur for the higher molecular weight PAHs,
ratio per ng from the calibration and sample waters. The area
because the dilution of lowest calibration standard is likely to
ratio per ng is calculated for calibration runs by dividing the
be below detection limits for many labs (and is also below the
calibration peak area by the peak area of its most closely
required detection limits needed for the method, so it does not
associate d-PAH internal standard (the deuterated parent PAH,
negatively impact the analyses). In such cases, the lowest
in most cases), and dividing this result by the ng of the
calibration standard is ignored, and the “J” level adjusted
calibration PAH present in the vial (that is, its mass in the vial,
appropriately.Lessfrequently,thehighestconcentrationsofthe
not its concentration). Calibration standards are given in Table
lowest molecular weight PAHs may exceed the linear dynamic
5.
range of the GC/MS response. In such cases the laboratory
@~peak area cal std!/~peak area d 2 PAHint std!#
should investigate lowering the MS multiplier voltage to
ar rat/ng 5 (1)
mass of std in cal vial
~ !
autotune voltage or slightly below and rerun the calibration
curve. If the highest calibration standard still exceeds the
where:
detector linearity, it is acceptable to reject the highest concen-
ar rat/ng = area ratio per ng,
tration for those specific PAHs (and adjust the “E” value
(3) Calculate the mean ar rat/ng. The mean relative
accordingly), as long as a minimum of a three-point standard
response factor for these duplicate daily calibration standards
curve is generated for each PAH.
should agree with those from the 4-point (or 3-point) standard
12.3.1.1 Itisrecommendedthata4-point(or3-point)initial
curvewithin20%forthetwoandthree-ringPAHs,andwithin
calibration be established every two weeks, when continuing
25% for the four-ring PAHs. No sample data will be reported
calibration criteria are not met, or when service is performed
ifthesecalibrationcriteriaarenotmet.Calculatethemeanarea
on the GC/MS instrument system.
ratio/ng and the standard deviation of the relative response
12.3.2 The signal to noise ratio (S/N) for the GC signals
factors for each calibration standard solution using the follow-
present in every selected ion current profile (SICP) must be
ing equations:
≥10:1 for the labeled internal standards and unlabeled calibra-
n
tion compounds.
¯
ar rat/ng 5 arrat/ng (2)
~ !
(
i
n
i51
12.4 Calibration Verification—Continuing calibration is
where:
performed daily at the beginning of a 24-h period. The
injection of the first continuing calibration begins the 24-h
ar rat/ng = ar rat/ng calculated for calibration solution “i”
~ !
i
window,withinwhichallporewatersamplesmustbeinjected.
using Eq 1, and
Duplicate daily standards are analyzed.
n = number of calibration points in the curve.
12.4.1 Into 1.5 mL of reagent water, add 4 µL of the CS3
(4) Calculate the percent relative standard deviation:
spiking solution and 10 µL of the d-PAH internal standards.
SD
12.4.2 Analyze duplicate vials of the Calibration Standard
%RSD 5 3100 (3)
¯
ar rat/ng
Solution CS3. Use the same data acquisition parameters as
those used during the initial calibration. Check for GC resolu-
where:
tion and peak shape. If peak shape or retention times are
¯
= mean ar rat/ng calculated above, and
ar□rat/ng
unacceptable,performcolumnandinjectormaintenance.Ifthis
SD = sample standard deviation of the replicate area
fails to correct the problem, the column must be replaced and
rat/ngvaluesusedtocalculatethemeanarrat/ng.
the calibration repeated.
12.3 Criteria for Acceptable Initial Calibration—Prior to
12.4.3 Criteria for Acceptable Daily Calibration Check—
analyzing any samples, the standard curves are prepared using
Thecriterialistedbelowforacceptablecalibrationmustbemet
the identical analysis procedures as used for sample waters.To atthebeginningofeach24-hperiodthatsamplesareanalyzed.
be acceptable, the linearity of each PAH standard curve should
The mean relative response factor for these duplicate daily
be r >0.99, and the area ratio per ng for each concentration calibration standards should agree with those from the 4-point
should show a relative standard deviation of <25% for two- to
(or 3-point) standard curve within 20% for the two- and
three-ring PAHs, and <30% for four-ring PAHs. See Section three-ring PAHs, and within 25% for the four-ring PAHs. No
16. If acceptable initial calibration is not achieved, identify the sample data will be reported if these calibration criteria are not
root cause, perform corrective action, and repeat the initial met. If the continuing calibration criteria are not met, identify
´1
D7363 − 13a (2021)
the root cause, perform corrective action and repeat the sample (not including replicates). Significant carryover can
continuing calibration. If the second consecutive continuing occur if the previous sample was highly contaminated. Should
calibration does not meet acceptance criteria, additional cor-
the blank prior to the subsequent pore water sample have
rective action must be performed.
detectable background concentrations more than ⁄3 of the
targetdetectionlimit,theanalysesshouldnotcontinueuntilthe
12.5 Method Blanks—Method blanks are prepared and ana-
fiber is sufficiently cleaned as demonstrated by a clean water
lyzed daily in duplicate following the continuing calibration
and between analysis of replicate sets of the same pore water blank. Alternatively, if the concentrations determined in the
sample. See 12.5.2.2. blanks are less than 20% of those found in the related sample,
12.5.1 For each method blank, add 10 µL of the d-PAH
the data can be accepted.
internal standards solution into 1.5 mL of reagent water.
12.6 Determining Relative Response Factors (RRFs)—All
12.5.2 Two types of sources of background PAHs must be
parent PAHs on the target compound list (and the 1- and 2-
considered. For the higher molecular weight PAHs, typical
methylnaphthalene isomers) are included in the calibration
GC/MS criteria for signal to noise are appropriate, since their
standard, so RRFs are not relevant to the parent PAH since
detection limits are normally controlled by GC/MS sensitivity.
each parent PAH is quantitated based on the same parent PAH
However, for lower molecular weight PAHs, atmospheric
in the calibration standard. RRFs for alkyl PAH isomeric
contaminants can cause significant background peaks, espe-
clusters are determined by each laboratory by comparing the
cially for low MW alkyl PAHs. This problem is most likely to
be significant in urban areas impacted by atmospheric PAHs alkyl cluster ar rat/ng to the ar rat/ng of the related parent PAH
(forexample,fromdieselexhaust),andwithlaboratoriesusing
as determined by the analysis of a spiked pore water sample
manual techniques, rather than the SPME autosampler.
preparedfromSRM1991.TheRRFsforthealkylPAHsshould
12.5.2.1 Background PAHs from Ambient Air—
be determined every time the 4-point (or 3-point) calibration
Concentrations of each PAH in the water blanks should be
curve is determined (12.3.1.1). Duplicate 1.5 mL water
calculated in the same manner as a sample. Should the
...