United States
Environmental Protection
Agency
Method 541: Determination of 1-Butanol, 1,4-Dioxane,
2-Methoxyethanol and 2-Propen-l-ol in Drinking Water
by Solid Phase Extraction and Gas Chromatography/Mass
Spectrometry
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Questions concerning this document should be addressed to:
Steyen_C^A/end^lkenJ_PhD
U.S. EPA, Office of Ground Water and Drinking Water, Standards and Risk Management Division,
Technical Support Center, 26 W. Martin Luther King Dr. Cincinnati, OH 45268
Phone:(513)569-7491
w§nde|ken.steye(^eQa.goy
Off ice of Water (MS-140)
EPA815-R-15-011
EPA contract EP-C-12-013
November, 2015
Don Shelly and Xiaoyan Wang, Ph.D., UCT, Inc. (Bristol, PA)
Michael S. Young, Ph.D., Mark Capparella, and Jeremy Shia, Waters Corporation (Milford, MA)
Paul Grimmett, U.S. EPA Office of Research and Development (Cincinnati, OH)
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1 Scope and application 1
1.1 AnalyteList 1
1.2 Supporting Data 1
1.3 Method Flexibility 1
2 Summary of the Method 1
3 Definitions 2
3.1 Analysis Batch 2
3.2 Calibration Standard 2
3.3 Continuing Calibration Check (CCC) 2
3.4 Extraction Batch 2
3.5 Field Duplicates (FD) 2
3.6 Internal Standard (IS) 2
3.7 Laboratory Fortified Blank (LFB) 2
3.8 Laboratory Fortified Sample Matrix (LFSM) 2
3.9 Laboratory Fortified Sample Matrix Duplicate (LFSMD) 3
3.10 Laboratory Reagent Blank (LRB) 3
3.11 Lowest Concentration Minimum Reporting Level (LCMRL) 3
3.12 Minimum Reporting Level (MRL) 3
3.13 Primary Dilution Standard (PDS) 3
3.14 Quality Control Sample (QCS) 3
3.15 Reagent Water 3
3.16 Safety Data Sheets 3
3.17 Selected Ion Monitoring (SIM) 3
3.18 Stock Standard Solution 3
3.19 Surrogate Analyte 4
4 Interferences 4
4.1 Glassware, Reagents and Equipment 4
4.2 Matrix Interferences 4
4.3 Extraction Cartridges 4
4.4 Matrix Effects in the Presence of Water 4
4.4.1 Nitrogen-drying Manifold 4
4.4.2 Optimizing the Cartridge Drying Step 5
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4.5 Analyte Extraction Efficiency 5
4.6 Extraction Flow Rate 5
4.7 QC Compounds 5
5 Safety 5
5.1 Chemicals 5
5.2 Sodium Bisulfate 5
5.3 Dichloromethane 5
6 Equipment and Supplies 5
6.1 Sample Containers 5
6.2 Vials 6
6.3 Micro Syringes 6
6.4 Volumetric Pipettes 6
6.5 Analytical Balance 6
6.6 Compressed Gas: Helium 6
6.7 Compressed Gas: Nitrogen 6
6.8 Compressed Gas: Air 6
6.9 Disposable Pasteur Pipettes 6
6.10 Volumetric Flasks 6
6.11 Solid Phase Extraction Apparatus for Cartridges 6
6.11.1 UCT EU-541 SPE Cartridge 6
6.11.2 Waters AC-2 SPE Cartridge 6
6.11.3 Vacuum Extraction Manifold 6
6.11.4 Sample Delivery System 7
6.11.5 Extract Collection Tubes 7
6.12 Laboratory Vacuum System 7
6.13 Drying Manifold for SPE Cartridges 7
6.14 Flow Meter for Drying Manifold 7
6.15 Gas Chromatograph/Mass Spectrometer (GC/MS) 7
6.15.1 Column 7
6.15.2 GC Inlet 7
6.15.3 Inlet Liner for Split/Splitless Inlet 7
6.15.4 GC/MS Interface 7
6.15.5 Mass Spectrometer (MS) 7
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6.15.6 Data System 8
7 Reagents and Standards 8
7.1 Methanol 8
7.2 Dichloromethane 8
7.3 Sodium Sulfate, Anhydrous 8
7.4 Sample Preservation Reagents 8
7.4.1 Sodium Sulfite 8
7.4.2 Sodium Bisulfate 8
7.5 Stock Standard Solutions 8
7.5.1 Internal Standard Stocks 8
7.5.2 Surrogate Analyte Stock Standards 8
7.5.3 Method Analyte Stock Standard Solutions 9
7.5.4 Preparation Instructions for Analytes Obtained as Neat Compounds 9
7.5.5 Storage of Stock Standards 9
7.6 Primary Dilution Standards (PDS) 9
7.6.1 Internal Standard Primary Dilution Standard 9
7.6.2 Surrogate Analyte Primary Dilution Standard 9
7.6.3 Method Analyte Primary Dilution Standard 9
7.7 Calibration Standards 10
7.7.1 Example Calibration Scheme 10
7.7.2 Dilution Scheme for Calibration Standards 10
7.7.3 Storage of Calibration Standards 11
7.7.4 GC/MS Tune Check Solution 11
8 Sample Collection, Preservation, and Storage 11
8.1 Sample Bottles 11
8.2 Sample Collection 11
8.3 QC Samples 11
8.4 Sample Shipment and Storage 11
8.5 Verification upon Receipt 11
8.6 Sample Holding Time 11
8.7 Storage of Extracts 11
8.8 Extract Holding Time 11
9 Quality Control 12
IV
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9.1 Optimizing SPE Cartridge Drying Parameters 12
9.1.1 Prepare for the Test 12
9.1.2 Condition SPE Test Cartridges 12
9.1.3 Dry the Cartridges 12
9.1.4 Flow Rate and Volumes used during Method Development 12
9.1.5 Elute the Test Cartridges 13
9.1.6 Estimate the Minimum Required Nitrogen Volume 13
9.1.7 Analyze and Evaluate the Extracts 13
9.1.8 Select a Volume above the Minimum 13
9.2 Initial Demonstration of Capability (IDC) 13
9.2.1 Demonstration of Low System Background 13
9.2.2 Demonstration of Precision 13
9.2.3 Demonstration of Accuracy 14
9.2.4 Minimum Reporting Level (MRL) Confirmation 14
9.2.5 Quality Control Sample (QCS) 14
9.3 Ongoing QC Requirements 15
9.3.1 Laboratory Reagent Blank (LRB) 15
9.3.2 Continuing Calibration Check (CCC) 15
9.3.3 Laboratory Fortified Blank 15
9.3.4 BFB MS Tune Check 15
9.3.5 Internal Standards (IS) 16
9.3.6 Surrogate Recovery 16
9.3.7 Laboratory Fortified Sample Matrix (LFSM) 16
9.3.8 Field Duplicate or Laboratory Fortified Sample Matrix Duplicate (FD or LFSMD) 17
9.3.9 Retention Time Shifts 18
9.3.10 Quality Control Sample (QCS) 18
9.4 Method Modification QC Requirements 18
9.4.1 Repeat the IDC 18
9.4.2 Document Performance in Representative Sample Matrixes 18
9.4.3 Monitor Performance of the Modified Method 19
10 Calibration and Standardization 19
10.1 GC/MS Optimization 19
10.1.1 MS Tune and MS Tune Check 19
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10.1.2 GC Conditions 19
10.1.3 SIM MS Conditions 20
10.1.4 Suggested Ions and Dwell Times 20
10.2 Initial Calibration 20
10.2.1 Calibration Standards 20
10.2.2 Calibration Curve 20
10.2.3 Calibration Acceptance Criteria 20
10.3 Continuing Calibration Checks (CCCs) 21
10.3.1 Internal Standard Responses 21
10.3.2 Surrogate Analytes 21
10.3.3 Method Analytes 21
10.4 Corrective Action 21
11 Procedure 21
11.1 Sample Preparation 21
11.1.1 QC Samples 22
11.1.2 Surrogate Analytes 22
11.2 Extraction Procedure Using Waters AC-2 SPE Format 22
11.2.1 Set up the Extraction Manifold 22
11.2.2 Cartridge Cleaning 22
11.2.3 Cartridge Conditioning 22
11.2.4 Sample Loading 22
11.2.5 Cartridge Drying 22
11.3 Extraction Procedure using UCT EU-541 SPE Format 23
11.3.1 Set Up the Extraction Manifold 23
11.3.2 Cartridge Cleaning 23
11.3.3 Cartridge Conditioning 23
11.3.4 Sample Loading 23
11.3.5 Cartridge Drying 23
11.4 Cartridge Elution 24
11.5 Internal Standard Addition 24
11.6 Extract Drying 24
11.7 Analysis of Sample Extracts 24
11.8 The Analysis Batch 24
VI
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11.8.1 Initial CCC 25
11.8.2 Field and QC Samples 25
11.8.3 CCC Frequency 25
11.8.4 Final CCC 25
11.8.5 Initial Calibration Frequency 25
12 Data Analysis and Calculations 25
12.1 Establish Retention Time Windows 25
12.2 Identify Analytes by Retention Time 25
12.3 Confirm Analyte Identifications 25
12.4 Compound Quantitation 26
12.5 Data Review 26
12.6 Exceeding the Calibration Range 26
13 Method Performance 26
13.1 Precision, Accuracy, and LCMRL Results 26
13.2 Analyte Stability Study 26
13.3 Extract Storage Stability 27
14 Pollution Prevention 27
15 Waste Management 27
16 References 27
17 Tables, Figures, and Method performance Data 28
Table 1. 4-Bromofluorobenzene (BFB) Mass Intensity Criteria 28
Table 2. Gas Chromatography/Mass Spectrometry (GC/MS) Conditions 28
Table 3. Retention Times, Quantitation Ions, and Internal Standard Assignments3 29
Table 4. LCMRL Results for the Waters AC-2 SPE Format 29
Table 5. Precision and Accuracy Data for Reagent Water: Waters AC-2 SPE Format 29
Table 6. Precision and Accuracy Data for Ground Water: Waters AC-2 SPE Format 30
Table 7. Precision and Accuracy Data for Surface Water: Waters AC-2 SPE Format 30
Tables. LCMRL Results for the UCT EU-541 SPE Format 30
Table 9. Precision and Accuracy Data for Reagent Water: UCT EU-541 SPE Format 31
Table 10. Precision and Accuracy Data for Ground Water: UCT EU-541 SPE Format 31
Table 11. Precision and Accuracy Data for Surface Water: UCT EU-541 SPE Format 32
Table 12. Aqueous Sample Holding Time Data (n=4) 33
Table 13. Holding Time Data for Sample Extracts (n=4) 33
VII
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Table 14. Initial Demonstration of Capability (IDC) Quality Control Requirements 34
Table 15. Ongoing Quality Control Requirements 34
Figure 1. Drying apparatus and proper placement of rotameter in flow path 36
Figure 2. Reconstructed ion chromatogram (RIC), SIM mode, for calibration standard 37
Figure 3. Extracted ion current profiles for calibration standard; concentrations as listed 38
Figure 4. RIC, SIM mode, for unfortified drinking water from a surface water source 39
Figure 5. RIC, SIM mode, for unfortified drinking water from a ground water source 40
VIII
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1 application
Method 541 is a gas chromatography (GC) method for the determination of 1-butanol, 1,4-dioxane,
2-methoxyethanol, and 2-propen-l-ol in finished drinking water. Method 541 requires detection using
mass spectrometry (MS) in selected ion monitoring (SIM) to provide selectivity for the method analytes.
This method is intended for use by analysts skilled in the performance of solid phase extractions, the
operation of GC/MS instrumentation and in the interpretation of the associated data.
1.1 Analyte List
Analyte
1-butanol
1,4-dioxane
2-methoxyethanol
2-propen-l-ol (allyl alcohol)
Chemical Abstracts Services
Registry Number (CASRN)
71-36-3
123-91-1
109-86-4
107-18-6
1.2 Supporting Data
Precision and accuracy data have been generated for the detection of the method analytes in reagent
water and finished drinking water from both ground water and surface water sources (Sect. 17,
Tables 5-7 and Sect. 17, Tables 9-11). Single-laboratory Lowest Concentration Minimum Reporting
Levels (LCMRL) (Sect. 3.11) for the analytes in this method are presented in Section 17, Table 4 and
Table 8. Laboratories using this method are not required to determine LCMRLs, but they must
demonstrate that the Minimum Reporting Level (MRL) (Sect. 3.12) for each analyte meets the
requirements described in Section 9.2.4.
1.3 Flexibility
The laboratory is permitted to select GC columns, inlets, and GC conditions different from those utilized
to develop the method. However, the basic chromatographic elements of the method must be retained.
At a minimum, the internal standards and surrogate analytes specified in the method must be used.
Changes may not be made to sample collection and preservation (Sect. 8). the quality control (QC)
requirements (Sect. 9), or the extraction procedure (Sect. 11). Method modifications should be
considered only to improve method performance. In all cases where method modifications are
proposed, the analyst must perform the procedures outlined in the Initial Demonstration of Capability
(IDC, Sect. 9.2), verify that all QC acceptance criteria in this method (Sect. 9.3) are met, and verify
method performance in representative sample matrixes (Sect. 9.4).
2 Summary of the Method
Samples (0.05 L) are collected in amber, glass bottles containing the method preservatives, sodium
sulfite (dechlorination) and sodium bisulfate (pH adjustment). In the laboratory, two surrogate analytes
are added. The method and surrogate analytes are isolated from water using solid phase extraction
(SPE). The SPE cartridges are dried to remove adsorbed water and eluted with 2 mL of 5% methanol in
dichloromethane. Extracts are analyzed, without further concentration, by GC/MS in the SIM mode of
detection. The method analytes are identified by comparing the retention times and ion abundance
ratios to reference retention times and ion abundance ratios obtained from calibration standards
acquired under identical GC/MS conditions. The concentrations of 1-butanol, 1,4-dioxane,
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2-methoxyethanol, and 2-propen-l-ol are calculated using the integrated peak area and the internal
standard technique.
3 Definitions
3,1 Analysis Batch
A set of samples that is analyzed on the same instrument during a 24 hour period that begins and ends
with the analysis of the appropriate Continuing Calibration Check (CCC) standards. Additional CCCs may
be required depending on the length of the Analysis Batch and the number of field samples.
3,2 Calibration Standard
A solution of the method analytes, surrogate analytes, and internal standards prepared from the
Primary Dilution Standards. The calibration standards are used to calibrate the instrument response with
respect to analyte concentration.
3,3 Continuing Calibration Check (CCC)
A calibration standard that is analyzed periodically to verify the accuracy of the existing calibration.
3,4 Extraction Batch
A set of up to 20 field samples (not including QC samples) extracted together using the same lot of solid
phase extraction devices, solvents, surrogate solution, and fortifying solutions.
3,5 Field Duplicates (FD)
Separate samples collected at the same time, shipped and stored under identical conditions. Method
precision, including the contribution from sample collection procedures, is estimated from the analysis
of Field Duplicates. Field Duplicates are used to prepare Laboratory Fortified Sample Matrix and
Laboratory Fortified Sample Matrix Duplicate QC samples. For the purposes of this method, Field
Duplicates are necessary to conduct repeat analyses if the original field sample is lost, or to conduct
repeat analyses in the case of QC failures associated with the analysis of the original field sample.
3.6 Internal Standard (IS)
A pure compound that is added to all standard solutions and extracts in a known amount and used to
measure the relative response of method analytes that are components of the same solution. The IS
should respond to instrument conditions and sample matrix in a similar manner as the method analytes,
and have no potential to be present in the samples.
3,7 Laboratory Fortified (LFB)
An aliquot of reagent water, containing method preservatives, to which known quantities of the method
analytes are added. The LFB is used during the IDC to verify method performance for precision and
accuracy. The LFB is also a required QC element with each Extraction Batch. The results of the LFB verify
method performance in the absence of sample matrix.
3,8 Laboratory Fortified Sample Matrix (LFSM)
An aliquot of a field sample to which known quantities of the method analytes are added. The purpose
of the LSFM is to determine whether the sample matrix contributes bias to the analytical results. For this
method, separate field samples are required for preparing fortified matrix so that sampling error is
included in the accuracy estimate.
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3.9 Laboratory Fortified Sample Matrix Duplicate (LFSMD)
A Field Duplicate of the sample used to prepare the LFSM that is fortified and analyzed identically to the
LFSM. The LFSMD is used instead of the Field Duplicate to assess method precision when the method
analytes are rarely found at concentrations greater than the MRL
3.10 Laboratory Reagent Blank (LRB)
An aliquot of reagent water that contains the preservatives and surrogate analytes. An LRB is included in
each Extraction Batch to determine if the method analytes or other interferences are introduced from
the laboratory environment, the reagents, glassware, or extraction apparatus.
3.11 Lowest Concentration Minimum Reporting Level (LCMRL)
The single-laboratory LCMRL is the lowest spiking concentration such that the probability of spike
recovery in the 50% to 150% range is at least
3.12 Minimum Reporting Level (MRL)
The minimum concentration that can be reported by a laboratory as a quantified value for a method
analyte following analysis. For each method analyte, this concentration must meet the criteria defined in
Section 9.2.4 and must be greater than or equal to the concentration of the lowest calibration standard.
3.13 Primary Dilution Standard (PDS)
A solution that contains compounds prepared from stock standards. PDS solutions are diluted to
prepare calibration standards and sample fortification solutions, and are used to fortify QC samples.
3.14 Quality Control Sample (QCS)
A solution containing the method analytes at a known concentration that is obtained from a source
external to the laboratory and different from the source of calibration standards. The purpose of the
QCS is to verify the accuracy of the primary calibration standards.
3.15 Reagent Water
Purified water that does not contain any measurable quantity of the method analytes or interfering
compounds at, or above, one-third of the MRL.
3.16 Safety Data Sheets
Written information provided by vendors concerning a chemical's toxicity, health hazards, physical
properties, fire and reactivity data, storage instructions, spill response procedures, and handling
precautions.
3.17 Selected ion Monitoring (SIM)
A GC/MS technique where only one or a few ions are monitored instead of scanning over a selected
mass range. When used with gas chromatography, the set of ions monitored is usually changed
periodically throughout the chromatographic run to correlate with the characteristic ions of the analyte,
surrogates, and internal standards as they elute from the chromatographic column.
3.18 Stock Standard Solution
A concentrated standard solution that is prepared in the laboratory using assayed reference materials or
that is purchased from a commercial source with a certificate of analysis.
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3.19 Surrogate Analyte
A pure compound, chemically similar to the method analytes, that is unlikely to be found in any sample.
The surrogate is added to each sample in a known amount before extraction. Surrogates are quantitated
using the same procedures as other sample components. Because surrogates are present in every
sample, they provide a means of assessing method performance for each sample extraction.
4.1 Glassware, Equipment
Method interferences may be caused by contaminants in solvents, reagents (including reagent water),
sample bottles and caps, and other sample processing hardware. All laboratory reagents and equipment
must be routinely demonstrated to be free from interferences under the conditions of the analysis. This
may be accomplished by analyzing LRBs as described in Section 9.3.1.
4.2 Matrix Interferences
Matrix interferences may be caused by contaminants that are co-extracted from the sample. The extent
of matrix interferences will vary considerably from source to source depending upon the nature of the
water. Matrix components may directly interfere by producing a signal at or near the retention time of
an analyte peak. Matrix components may also suppress or enhance the signal of the method analytes.
(Suppression and enhancement effects occur within the GC inlet when co-eluting contaminants
influence the transmission efficiency of an analyte to the column.) Humic and fulvic material in
environmental samples may be co-extracted during SPE and can cause enhancement and suppression.
Total organic carbon (TOC) is an indicator of the humic content of a sample if such information is
available. The analysis of Laboratory Fortified Sample Matrix provides evidence for the presence (or
absence) of matrix effects.
4.3 Extraction Cartridges
Solid phase extraction cartridges may be a source of interferences. The analysis of LRBs provides
important information regarding the presence or absence of such interferences. Each brand and lot of
SPE devices should be monitored to ensure that contamination does not preclude analyte identification
and quantitation. It is recommended to keep SPE cartridges sealed while in storage in order to prevent
contamination of SPE sorbent.
4.4 Matrix in the Presence of Water
During method development studies, matrix enhancement, matrix suppression, and retention time
shifts were observed when analyzing extracts containing residual water from the extraction procedure.
These effects are eliminated by drying SPE cartridges prior to solvent elution and by adding a desiccant
to the organic extract. It is important to follow all of the steps in the extraction procedure (Sect. 11)
related to water management.
4.4.1 Nitrogen-drying Manifold
A drying manifold designed for SPE cartridges is required for this method. A rotameter or other
appropriate flow measurement device must be placed in the delivery line to the nitrogen-drying
manifold to ensure that the volume of gas passing through the SPE cartridges is consistent for each
Extraction Batch.
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4.4.2 Optimizing the Cartridge Drying Step
The laboratory is required to optimize the nitrogen volume for each SPE format prior to conducting the
method (during the IDC). The gas volumes recommended in Section 9.1.4 are good starting parameters.
The authors verified these values for each extraction format across multiple lots of cartridges.
4,5 Analyte Extraction Efficiency
Overall extraction efficiency for 2-propen-l-ol is lower than the other analytes. Typical recovery for
2-propen-l-ol can be expected to fall in the 80 to 90% range. Typical recovery for 1-butanol and
2-methoxyethanol can be expected to fall in the 80 to 100% range. 1,4-Dioxane is routinely recovered
near 100%.
4.6 Extraction Flow Rate
During method development, the authors observed low analyte recovery for some extractions when the
flow rate during loading of the SPE cartridges exceeded 10 mL/min. For this reason, a loading rate of
5 mL/min is recommended for this method.
4.7 QC Compounds
Depending on the source and purity, labeled analogs used as internal standards and surrogates may
contain a small percentage of the corresponding native analyte. Such a contribution may be significant
when attempting to determine MRLs.
5
5.1 Chemicals
Each chemical should be treated as a potential health hazard and exposure to these chemicals should be
minimized. Each laboratory is responsible for maintaining an awareness of OSHA regulations regarding
safe handling of chemicals used in this method. A reference file of safety data sheets should be made
available to all personnel involved in the chemical analysis.
5,2 Sodium Bisulfate
Sodium bisulfate is used as a sample preservative to inhibit microbial growth. Sodium bisulfate is highly
acidic and should be used with appropriate caution.
5,3 Dichloromethane
The primary hazard when conducting the procedures in this method is exposure to dichloromethane.
This solvent is a possible human carcinogen, volatilizes readily with vapors heavier than air, and quickly
permeates many types of common laboratory gloves. Handle this material with appropriate protection
for the eyes, skin, and respiratory system. Always perform extractions and prepare standard solutions in
a laboratory fume hood.
t< I (jijipnitTit «-ind Supple,
References to specific brands and catalog numbers are included as examples only and do not imply
endorsement of the products. Such reference does not preclude the use of other vendors or suppliers.
6,1 Sample Containers
Amber glass bottles or vials fitted with polytetrafluoroethylene (PTFE) lined screw caps.
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6.2 Vials
Various sizes of amber glass vials with PTFE-lined screw caps for storing standard solutions. Amber or
clear glass, 2 ml autosampler vials with PTFE-faced septa.
6.3 Micro Syringes
Suggested sizes include 5, 10, 25, 50, 100, 250 and 1000 microliters.
6.4 Volumetric Pipettes
Class A.
6.5 Analytical Balance
Capable of weighing to the nearest 0.0001 gram.
6.6 Compressed Gas: Helium
Ultra-high-purity; for use as the GC carrier. Alternate carrier gases, such as hydrogen (99.999% or better)
may be used if the QC criteria in Sect. 9 are met. Instrument manufacturers should be consulted prior to
any GC carrier gas conversion.
6.7 Compressed Gas: Nitrogen
Ultra-high-purity; for drying SPE cartridges.
6.8 Compressed Gas: Air
Ultra-high-purity; for drying SPE cartridges.
6.9 Disposable Pasteur Pipettes
Five and three-fourths inch borosilicate glass, used to transfer samples to autosampler vials (Fisher Cat.
No. 13-678-20B or equivalent).
6.10 Volumetric Flasks
Class A, suggested sizes include 2, 5, and 10 ml for preparation of primary dilution standards and
calibration standards [Pyrex Brand Cat. No. 5640-2 (2 ml), 5640-5 (5 ml), and 5640-10 (10 ml)]. The
2 ml size is used to receive the sample eluate during the elution step in the extraction procedure.
6.11 Solid Phase Extraction Apparatus for Cartridges
6.11.1 UCTEU-541 SPE Cartridge
UCT, Inc., (Bristol, PA) EU-541 activated carbon (Cat. No. EU541163), 600 mg, 3 ml cartridge; requires
tube adaptor (Supelco Cat. No. 57020-U, UCT Cat. No. ADOOOOAS, or equivalent) to attach sample
reservoir to cartridge and to attach cartridge to the drying manifold.
6.11.2 Waters AC-2 SPE Cartridge
Waters Corporation (Milford, MA) AC-2 activated carbon (Cat. No. JJAN20229), 400 mg, reversible
cartridge; requires 3 ml solvent reservoir (Supelco Cat. No. 57241 or equivalent).
6.11.3 Vacuum Extraction Manifold
Equipped with flow and vacuum control [Supelco Cat. No. 57030-U, UCT Cat. No. VMF016GL (the later
requires UCT Cat. No. VMF02116 control valves), or equivalent systems]. Automated devices designed
for use with SPE cartridges may be used; however, all extraction and elution steps must be the same as
in the manual procedure. Extraction and elution steps may not be changed or omitted to accommodate
the use of an automated system.
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6.11.4 Sample Delivery System
Polypropylene sample reservoirs (60 ml Restek Cat. No. 26015, 75 ml UCT Cat. No. RFV0075P, or
equivalent) which attach to the cartridge, are recommended.
6.11.5 Extract Collection Tubes
Two ml volumetric flasks (Pyrex Brand Cat. No. 5640-2 or equivalent) suitable for collection of eluate
from the SPE cartridges.
6.12 Laboratory Vacuum System
Sufficient capacity to maintain a vacuum of approximately 20 inches of mercury.
6.13 Drying Manifold for SPE Cartridges
Manifold with flow control valve (Supelco Visidry™ Drying Attachment, Cat. No. 57100-U, or equivalent).
6.14 Flow Meter for Drying Manifold
Rotameter, 0-30 liters/min [Organomation Associates, Inc., (Berlin, MA) Cat. No. NA-1421 or
equivalent]. Install the rotameter between the gas supply and the drying manifold. See Section 17,
Figure 1, for additional guidance.
6.15 Gas Chromatograph/Mass Spectrometer (GC/MS)
Analytical system complete with temperature programmable GC suitable for use with capillary columns
and all required accessories including gas supply, liquid autosampler and data system. Table 3 in
Section 17 lists retention times observed for method analytes using the column and analytical conditions
described below.
6.15.1 Column
30 m x 0.25 mm i.d. polyethylene glycol (PEG; commonly called WAX), bonded-phase fused silica
column, 0.50 u.m film thickness. Helium carrier gas: 0.9 mL/min in constant flow mode. Oven
temperature program: 30 °C (5 min), 10 °C/min to 110 °C (0 min), 25 °C/min to 200 °C (6 min hold).
6.15.2 GC Inlet
Split/splitless injector operated in pulsed splitless mode (200 °C; 10-psig pulse pressure) with a
30 second split delay. The injection volume was one microliter.
6.15.3 Inlet Liner for Split/Splitless Inlet
Single-gooseneck splitless liner, 4 mm deactivated glass with deactivated glass wool.
6.15.4 GC/MS Interface
The interface should allow the capillary column or transfer line exit to be placed within a few millimeters
of the ion source. Other interfaces are acceptable as long as the system has adequate sensitivity and QC
performance criteria are met.
6.15.5 Mass Spectrometer (MS)
Any type of MS may be used that is capable of SIM or selected ion storage (SIS) mode (i.e., quadrupole
and ion trap) with electron impact ionization at 70 eV. The instrument must be operated in SIM mode
(or SIS) for enhanced sensitivity and selectivity. The minimum scan range capability of the MS must be
m/z 35 to 260, and it must produce a full scan mass spectrum that meets all criteria in Table 1 when a
solution containing one ng, or less, of bromofluorobenzene (BFB) is injected into the GC/MS.
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6.15.6 Data System
An interfaced data system is required to acquire, store and output GC/MS data. The computer software
must have the capability of processing stored data by recognizing a chromatographic peak within a given
retention time window. The software must be able to construct a linear regression or quadratic
regression calibration curve and calculate analyte concentrations using the internal standard technique.
7 Reagents and Standards
Reagent grade or better chemicals must be used. Unless otherwise indicated, all reagents must conform
to the specifications of the Committee on Analytical Reagents of the American Chemical Society (ACS),
where such specifications are available. Other grades may be used if the reagent is demonstrated to be
free of analytes and interferences and all requirements of the IDC are met when using these reagents.
7.1 Methanol
CH3OH, CASRN 67-56-1, purge-and-trap-grade (Honeywell, Burdick & Jackson brand, Cat. No. 232 or
equivalent). No other grades of methanol are permitted for this method.
7.2 Dichloromethane
DCM, CASRN 75-09-02, pesticide residue grade or equivalent. Use DCM to prepare the elution solvent:
5% methanol in DCM.
7.3 Sodium Sulfate, Anhydrous
Na2SO4, CASRN 7757-82-6, conditioned at 400 °C for at least four hours in a muffle furnace. An "ACS
grade, suitable for pesticide residue analysis" of granular, 10-60 mesh, anhydrous Na2SO4 is
recommended (Fisher Scientific Cat. No. S415 or equivalent).
7.4 Sample Preservation
These preservatives are solids and may be added to the sample bottle before shipment to the field.
7.4.1 Sodium Sulfite
Na2SO3, CASRN 7757-83-7, reduces residual chlorine at the time of sample collection.
7.4.2 Sodium Bisulfate
NaHSO4, CASRN 7681-38-1, reduces sample pH to inhibit microbial growth and prevent analyte
degradation.
7.5 Stock Standard Solutions
Vendor certified solutions of the method analytes, the internal standards, and the surrogate analytes
are recommended. Users may prepare stock standards starting with the neat liquid if not available as
certified solutions or sufficient concentration, following the guidance provided in this section. Useful
concentrations for stock standards are typically in the range of 1000-2000 u.g/mL
7.5.1 Internal Standard Stocks
This method requires two internal standards: l,4-dioxane-dg (CASRN 17647-74-4) and chlorobenzene-ds
(CASRN 3114-55-4). Obtain the internal standards as certified mixtures in methanol.
7.5.2 Surrogate Analyte Stock Standards
This method requires two surrogate standards: 1-butanol-dio (CASRN 34193-38-9) and 2-propen-l-ol-ds
(CASRN 1173018-56-8). Prepare a mixture of l-butanol-di0and 2-propen-l-ol-ds in purge-and-trap-
grade methanol. During method development, 1-butanol-dio was obtained as the neat compound from
8
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CDN Isotopes (Pointe-Claire, Quebec, Canada, Cat. No. D-1181). During method development,
2-propen-l-ol-de was obtained as the neat compound from Sigma-Aldrich (Cat. No. 614629).
7.5.3 Method Analyte Stock Standard Solutions
Obtain the analytes listed in Section 1.1 as certified mixes in methanol, or as neat standards if desired.
7.5.4 Preparation Instructions for Analytes Obtained as Neat Compounds
Prepare the stock standards individually at 2000 u.g/mL Using an analytical balance, obtain a tare weight
for a vial containing 20 ml of purge-and-trap-grade methanol. To achieve 2.0 mg/L nominal
concentrations, calculate the volume of the liquid analyte corresponding to 40 mg. Measure this volume
with a 100 u.L syringe and inject the entire quantity under the surface of the methanol. Subtract the tare
weight from the final weight to calculate the exact solution concentration. When a compound's purity is
assayed to be 96 percent or greater, the weight can be used without correction to calculate the
concentration of the stock standard.
7.5.5 Storage of Stock Standards
Experience indicates that the most likely cause of standard deterioration for this method is solvent
evaporation. After opening sealed ampoules, store commercial mixes in glass vials with Teflon closures
at -10 °C or lower temperature. Stock standard solutions prepared in-house are estimated to be stable
for at least one year if stored at -10 °C. Store these stocks in the vials in which they were prepared.
Laboratories should use appropriate QC practices to determine when stock standards need to be
replaced. Expiration dates of commercially available mixtures provided by the vendor can be used to
estimate shelf life of stock solutions if evaporation of the solvent is prevented.
7.6 Primary Dilution Standards (PDS)
Prepare Primary Dilution Standards by combining and diluting appropriate volumes of the stock
standards with purge-and-trap-grade methanol. Store the PDS solutions in glass vials with Teflon-lined
septa at -10 °C or lower temperature. During method development, PDS solutions were demonstrated
to be stable for at least one year; however, laboratories should use appropriate QC practices to
determine when PDS standards need to be replaced. The PDS concentrations appearing in this section
were used during method development, and are intended to be examples only.
7.6.1 Internal Standard Primary Dilution Standard
Prepare the internal standard PDS at 50 u.g/mL in methanol from the internal standard stock. The
authors added 10 ul to each 2 ml extract and calibration standard to achieve a concentration of 0.25
u.g/mL.
7.6.2 Surrogate Analyte Primary Dilution Standard
Prepare the surrogate standard PDS at 50 u.g/mL in methanol from the surrogate standard stock. The
authors added 10 ul to each 0.050 L sample to achieve a concentration of 10 u.g/L.
7.6.3 Method Analyte Primary Dilution Standard
The analyte PDS is used to prepare the calibration standards and to fortify LFB, LFSM and LFSMD QC
samples with the method analytes. Select nominal analyte concentrations for the PDS such that
between 5 and 25 ul of the PDS is used to fortify samples and prepare standard solutions. More than
one PDS concentration may be necessary to meet this requirement. The analyte PDS is prepared by
combining appropriate volumes of the analyte stock standard solutions in purge-and-trap-grade
methanol. During method development, three PDS solutions were used. The concentrations of these
solutions are listed in the table in Section 7.7.2.
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7.7 Calibration Standards
Prepare a series of calibration standards of at least six levels by diluting the analyte PDS into 5%
methanol in DCM. The lowest calibration standard must be at, or below, the concentration representing
the MRL in the aqueous sample for each analyte. Using the internal standard and surrogate PDS
solutions, add a constant amount of each internal standard and surrogate to each calibration standard.
The concentration of the surrogate analytes should match the concentration of the surrogates in sample
extracts, assuming 100% recovery through the extraction process. The calibration standards may also be
used as CCCs.
7.7.1 Example Calibration Scheme
The dilution scheme for calibration standards used to collect method performance data (Section 13) is
presented in Section 7.7.2. The right-most column gives the aqueous concentration of method analytes
achieved by fortifying the same quantity of PDS solution into a 0.050 L aqueous sample, e.g., when
preparing fortified field samples. Ten microliters of the internal standard PDS (50 u.g/mL) were added to
each calibration standard resulting in a concentration of 0.25 u.g/mL Ten microliters of the surrogate
PDS (50 u.g/mL) were added to each calibration standard resulting in a concentration of 0.25 u.g/mL in
the calibration standard (10 u.g/L aqueous sample equivalent).
7.7.2 Dilution Scheme for Calibration Standards
CALa Level
0.5 x MRL
Std. #1, MRLb
2
3
4
5
6
Analyte PDS(u.g/mL)
1,4-dioxane (0.40)
Alcohols, 2-MEa (2.0)
1,4-dioxane (4.0)
Alcohols, 2-ME (20)
1,4-dioxane (4.0)
Alcohols, 2-ME (20)
1,4-dioxane (4.0)
Alcohols, 2-ME (20)
1,4-dioxane (40)
Alcohols, 2-ME (200)
1,4-dioxane (40)
Alcohols, 2-ME (200)
1,4-dioxane (40)
PDS
Volume
(HL)
25
5.0
10
20
5.0
10
20
Final Std. Volume
5%methanol:DCM
(ml)
2.0
2.0
2.0
2.0
2.0
2.0
2.0
CAL
Std.c'd
(Hg/rnL)
0.0050
0.025
0.010
0.050
0.020
0.10
0.040
0.20
0.10
0.50
0.20
1.0
0.40
Aqueous
Equivalent
0.050 L Sample
(Mf/L)
0.20
1.0
0.40
2.0
0.80
4.0
1.6
8.0
4.0
20
8.0
40
16
a. CAL = calibration standard; alcohols = 1-butanol, 2-propen-l-ol; 2-ME = 2-methoxyethanol.
b. During method development, the MRL was confirmed at this level.
c. Ten u.L internal standard PDS (50 u.g/mL) added to each calibration standard results in a
concentration of 0.25 u.g/mL.
d. Ten ul surrogate PDS (50 u.g/mL) added to each calibration standard results in a concentration of
0.25 u.g/mL in the CAL standard (10 u.g/L aqueous sample equivalent).
10
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7.7.3 Storage of Calibration Standards
The stability of calibration standards was evaluated during method development at concentrations
within the calibration range. The calibration standards are stable for at least 6 months when stored in
autosampler vials with PTFE-faced silicone septa at -10 °C.
7.7.4 GC/MS Tune Check Solution
BFB, 1 u.g/mL, CASRN 460-00-4. Prepare in a solvent mixture identical to the extract solvent
composition.
8 Sample Collection, Preservation,
8.1 Sample Bottles
Prior to shipment to the field, add sodium sulfite and sodium bisulfate to each sample bottle: 2.5 mg of
sodium sulfite and 50 mg of sodium bisulfate. Cap the vials tightly to avoid spillage of the preservation
reagents. The final concentrations of sodium sulfite and sodium bisulfate in the sample are 50 mg/L and
1000 mg/L, respectively, for a 50 ml sample. Do not dilute these salts in water. The preservatives must
be added in the solid form.
8.2 Sample Collection
Open the tap and allow the system to flush for approximately 5 minutes. Using a graduated cylinder, fill
each bottle with exactly 50 ml of sample. Invert the bottle several times to mix the sample with the
preservatives. Rinse the graduated cylinder several times with the subsequent sample before filling the
next bottle.
8.3 QC Samples
Collect additional field samples to fulfill QC requirements for Field Duplicates, LFSMs, and LFSMDs. For
this method, all QC samples are prepared using duplicate samples collected in the field, i.e., not split
samples prepared in the laboratory.
8.4 Sample Shipment and Storage
Samples must be chilled during shipment and must not exceed 10 °C during the first 48 hours after
collection. In the laboratory, samples must be stored at, or below, 6 °C and protected from light.
8.5 Verification upon Receipt
Samples must be confirmed to be at, or below, 10 °C when they are received at the laboratory. When
samples are returned to the laboratory, use a pH meter to periodically verify that sample pH is less than
3 for each drinking water source. For each water source, analyze one sample using common assays for
residual chlorine, e.g., N,N diethyl-p-phenylenediamine (DPD)-colorimetric technique. Residual chlorine
should not be present in preserved water samples.
8.6 Sample Holding Time
Analyze samples as soon as possible. Samples must be analyzed within 28 days of collection.
8.7 Storage of Extracts
Store the 2 ml extracts obtained from the SPE procedure in a freezer at, or below, -10 °C.
8.8 Extract Holding Time
Extracts must be analyzed within 28 days after sample extraction.
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QC requirements include the IDC and ongoing QC requirements. This section describes each QC
parameter, its required frequency, and the performance criteria that must be met in order to satisfy EPA
quality objectives. The QC criteria discussed in the following sections are summarized in Section 17,
Table 14 and Table 15. These QC requirements are considered the minimum acceptable QC program.
Laboratories are encouraged to institute additional QC practices to meet their specific needs. Calibrate
the GC/MS system following the steps in Section 10 prior to optimizing the SPE cartridge drying
parameters and conducting the IDC.
9.1 Optimizing SPE Cartridge Drying Parameters
For this method, the SPE cartridge drying parameters must be optimized for each extraction format. The
goal is to produce dry extracts for GC analysis and to conserve compressed gas required by this method.
The WAX column is very sensitive to water in the extracts and retention time shifts will occur if residual
water is not completely removed. In addition, the authors observed suppression and enhancement of
analyte response when residual water was present in the extracts.
9.1.1 Prepare for the Test
Review the extraction procedure in Section 11. Pay particular attention to the steps for drying the AC-2
cartridges (Sect. 11.2.5) and the UCT EU-541 cartridges (Sect. 11.3.5) after sample loading. Proper drying
technique results in a clear, single-layer extract after elution: no cloudiness or separate water layer. In
addition, retention times observed during extract analysis should match those observed for calibration
standards. Perform the following experiment to identify the optimum volume for nitrogen drying.
Purified air (zero air) may be used in place of nitrogen; however, vacuum drying is not permitted.
9.1.2 Condition SPE Test Cartridges
Load two SPE cartridges onto the extraction manifold and condition with the following exception:
aspirate the reagent water in the final conditioning step for ~30 seconds and then close the manifold
valve. [For the Waters AC-2 format, remove the wet 3 mL reservoirs and replace them with dry
reservoirs.] Add 150 ul of methanol (Waters AC-2) or 200 ul of methanol (UCT EU-541) to each
reservoir and aspirate at full vacuum for ~30 seconds.
9.13 Dry the Cartridges
Set up the drying manifold, but do not attach it to the extraction lid. Install the rotameter between the
nitrogen regulator and the control valve on the drying manifold (Figure 1). Place the cartridges on the
drying manifold in the load direction. Start the nitrogen flow at between 2 and 5 L/min per cartridge
(total flow measured on the rotameter divided by the number of cartridges); start a timer and dry for
5 minutes. For the first one to two minutes, water is expelled from the bottom of the cartridges. With
continued flow, the sorbent visibly lightens in shade. While the cartridges are drying, dry the manifold
valves used during the conditioning step with methanol followed by vacuum aspiration (Sect. 11.2.5.3).
Do not omit this step: the valves hold a significant quantity of water.
9.1.4 Flow Rate and Volumes used during Method Development
A rotameter is sensitive to pressure drop across the device and the flow rate observed may not be
accurate. The authors recorded a true flow rate of 5.0 liters/min per cartridge as measured by a mass
flow meter when the rotameter indicated a flow rate of 2 L/min (nitrogen delivery pressure of 80 psig).
For example, when drying five cartridges, the mass flow meter read 25 liters/min while the rotameter
read 10 liters/min. As measured with a mass flow meter, the optimized nitrogen volumes were as
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follows: Waters AC-2 (5 L/min x 5 minutes = 25 liters per sample) and UCT EU-541 (5 L/min x 8 minutes =
40 liters per sample. Because the rotameter is used to repeat the total flow optimized in these steps,
accuracy is not required.
9.1.5 Elute the Test Cartridges
Replace the cartridges on the manifold in their original positions and elute with 2 ml of 5% methanol in
DCM following the procedure in Sect. 11.4. The extracts should be clear without a discernible water
layer. If the extracts are wet, repeat the experiment and incrementally increase the nitrogen flow or
time until a volume is reached that results in a clear, single-layer extract. Save these extracts for
Step 9.1.7.
9.1.6 Estimate the Minimum Required Nitrogen Volume
If the extracts contain no visible water after the first trial, repeat the experiment and incrementally
decrease the nitrogen volume. Determine the minimum volume of nitrogen that results in single-layer
extracts. Save these extracts for Step 9.1.7.
9.1.7 Analyze and Evaluate the Extracts
Fortify the extracts with analytes, internal standards, and surrogates and bring to volume (2 ml) with
elution solvent. Ensure that the sodium sulfate desiccant is properly conditioned. Dry the extracts with
sodium sulfate per Section 11.6. Analyze the extracts. The retention times should match those observed
for calibration standards. If retention time shifts occur, increase the nitrogen volume and repeat the
experiment until the problem is resolved.
9.1.8 Select a Volume above the Minimum
The authors determined empirically that up to six times the minimum volume necessary to eliminate
retention time shifts could be applied without adverse effects on method performance. However,
excessive drying (beyond this limit) decreased analyte recovery during the solvent elution step.
2-Propen-l-ol is the most sensitive analyte to over drying. The authors recommend adding a few
minutes to the drying time representing the optimized nitrogen volume to ensure retention time shifts
do not occur if operating conditions vary slightly, e.g., different lots of SPE media. Use the rotameter to
ensure that the optimized nitrogen volume is applied to all subsequent sample extractions.
9.2 Initial Demonstration of Capability (IDC)
The IDC must be successfully performed prior to analyzing field samples. The IDC must be repeated if
changes are made to analytical parameters not previously validated during the IDC, for example,
selection of alternate quantitation ions, extending the calibration range, or changing the internal
standard assignment of an analyte. Prior to conducting the IDC, the analyst must meet the calibration
requirements outlined in Section 10. The same calibration range used during the IDC must be used for
the analysis of field samples.
9.2.1 Demonstration of Low System Background
Analyze an LRB immediately after injecting the highest calibration standard in the selected calibration
range. Confirm that the blank is free from contamination as defined in Section 9.3.1.
9.2.2 Demonstration of Precision
Prepare, extract and analyze five replicate LFBs in a valid Extraction Batch (five replicate LFBs and an
LRB). Fortify the LFBs near the midpoint of the initial calibration curve. The method preservatives must
be added to the samples as described in Section 8.1. The percent relative standard deviation (%RSD) of
the concentrations of the replicate analyses must be less than, or equal to, 20% for all method analytes.
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Standard Deviation of Measured Concentrations
%RSD = x 100
Mean Concentration
9.2.3 Demonstration of Accuracy
Using the same set of replicate data generated for Section 9.2.2. calculate the average percent recovery.
The average percent recovery for each analyte must be within plus or minus 30% of the true value.
Average Measured Concentration
Average % Recovery = — x 100
Fortified Concentration
9.2.4 Minimum Reporting Level (MRL) Confirmation
Establish a target concentration for the MRL based on the intended use of the method. Analyze an initial
calibration following the procedures in Section 10. The lowest calibration standard used to establish the
initial calibration (as well as the low-level CCC) must be at, or below, the concentration representing the
MRL. Establishing the MRL concentration too low may cause repeated failure of ongoing QC
requirements. Confirm the MRL following the procedure outlined below.
9.2.4.1 Prepare and Analyze MRL Samples
Fortify, extract and analyze seven replicate LFBs at, or below, the proposed MRL concentration. The LFBs
must contain the method preservatives as specified in Section 8.1.
9,2,4,2 Calculate MRL Statistics
Calculate the mean and standard deviation for each analyte in these replicates. Determine the Half
Range for the Prediction Interval of Results (HRpm) using the following equation:
HRPIR = 3.963S
Where,
5 is the standard deviation and 3.963 is a constant value for seven replicates.1
Calculate the Upper and Lower Limits for the Prediction Interval of Results (PIR = Mean ± HRPiR) as shown
below.
Mean + HRPIp
Upper PIR Limit = —— — x 100
Fortified Concentration
Mean — HRPIp
Lower PIR Limit = —— — x 100
Fortified Concentration
9.2.4.3 MRL Acceptance Criteria
The MRL is confirmed if the Upper PIR Limit is less than, or equal to, 150%; and the Lower PIR Limit is
greater than, or equal to, 50%. If these criteria are not met, the MRL has been set too low and must be
confirmed again at a higher concentration.
NOTE: These equations are only valid for seven replicate samples.
9.2.5 Quality Control Sample (QCS)
Analyze a Quality Control Sample (Sect. 9.3.10) to confirm the accuracy of the primary calibration
standards.
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9.3 Ongoing OC Requirements
This section describes the ongoing QC elements that must be included when processing and analyzing
field samples.
9.3.1 Laboratory Reagent Blank (LRB)
Analyze an LRB with each Extraction Batch. The LRB must contain the method preservatives and the
surrogate analytes at the same concentration used to fortify field samples. Background from method
analytes or contaminants that interfere with the measurement of method analytes must be less than
one-third the MRL. If method analytes are detected in the LRB at concentrations equal to, or greater
than this level, then all data for the problem analyte(s) must be considered invalid for all samples that
yielded a positive result. Subtracting blank values from sample results is not permitted.
9.3.1.1 Estimating Background Concentrations
Although quantitative data below the MRL may not be accurate enough for data reporting, such data
are useful in determining the magnitude of background interference. Therefore, the analyte
concentrations in the LRB may be estimated by extrapolation when results are below the MRL.
9.3.1.2 Influence of Background on Selection of MRLs
It is important to evaluate background values of analytes that commonly occur in LRBs. The MRL should
be set at a value greater than three times the mean concentration observed in replicate LRBs. If LRB
values are highly variable, setting the MRL to a value greater than the mean LRB concentration plus
three times the standard deviation may provide a more realistic MRL.
9.3.1.3 Evaluation of Background when Analytes Exceed the Calibration Range
After analysis of a sample in which method analytes exceed the calibration range, one or more LRBs
must be analyzed (to detect potential carryover) until the system meets the LRB acceptance criteria. If
this occurs during an automated sequence, examine the results of samples analyzed following the
sample that exceeded the calibration range. If the analytes that exceeded the calibration range in the
previous sample are detected at, or above, the MRL, these samples are invalid. If the affected analytes
do not exceed the MRL, these subsequent samples may be reported.
9.3.2 Continuing Calibration Check (CCC)
Analyze CCC standards at the beginning of each Analysis Batch, after every tenth field sample, and at the
end of the Analysis Batch. See Section 10.3 for concentration requirements and acceptance criteria for
CCCs.
9.3.3 Laboratory Fortified Blank
An LFB is required with each Extraction Batch. The concentration of the LFB must be rotated between
low, medium, and high concentrations from batch to batch. The low concentration LFB must be within a
factor of two times the MRL. The high concentration LFB must be near the high end of the calibration
range established during the initial calibration. Results of the low-level LFB analyses must be within 50%
of the true value for each analyte. Results of the medium and high-level LFB analyses must be within
plus or minus 30% of the true value for each analyte. If the LFB results do not meet these criteria, then
all data for the problem analytes must be considered invalid for all samples in the Extraction Batch.
9.3.4 BFB MS Tune Check
A complete description of the MS Tune Check is found in Sect. 10.1.1. Perform the MS Tune Check in full
scan mode. The acceptance criteria for the MS Tune Check are summarized in Section 17, Table 1. The
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MS Tune Check must be performed each time a major change is made to the mass spectrometer and
prior to establishing or re-establishing an initial calibration. Daily BFB analysis is not required.
9.3.5 Internal Standards (IS)
The analyst must monitor the peak areas of the internal standards (1,4-dioxane-ds and
chlorobenzene-ds) in all injections of the Analysis Batch. The internal standard responses (as indicated
by peak areas) in any chromatographic run must not deviate by more than plus or minus 50% from the
average areas measured during the initial calibration. In addition, the peak areas must not deviate by
more than plus or minus 30% from the responses in the most recent CCC. If an IS area for a sample does
not meet these criteria, check the corresponding IS area of the most recent CCC and proceed as follows.
9.3.5.1 Corrective Action for Failed internal Standards in Samples
If the IS criterion is met in the CCC but not the sample, reanalyze the extract in a subsequent Analysis
Batch. If the IS area fails to meet the acceptance criteria in the repeat analysis, but passes in the most
recent CCC, extraction of the sample may need to be repeated provided the sample is still within the
holding time. If re-extraction is not possible, qualify the original sample results as "suspect-IS response."
Qualify only those analytes referenced to the failed internal standard.
9.3.5.2 Corrective Action for Failed Internal Standards in CCCs
If both the original field sample and the CCC fail the IS area criterion, take corrective action (e.g.,
Sect. 10.4). After servicing the instrument, re-inject the extract in a subsequent Analysis Batch. If the IS
area fails to meet the acceptance criteria in the repeat analysis, but passes in the most recent CCC,
extraction of the sample may need to be repeated provided the sample is still within the holding time. If
re-extraction is not possible, qualify the original sample results as "suspect-IS response." Qualify only
those analytes referenced to the failed internal standard.
9.3.6 Surrogate Recovery
The surrogate analytes are fortified into the aqueous portion of field samples and QC samples prior to
extraction. Calculate the percent recovery for each surrogate. Recovery must be in the range of 70 to
130%.
Calculated Surrogate Concentration
% Recovery = ( ) x 100
Fortified Concentration of Surrogate
9.3.8.1 Corrective Action for Failed Surrogates
If a surrogate fails to meet the recovery criterion, evaluate the recovery of the surrogate in the CCCs, the
integrity of the calibration solutions, and take corrective action such as recalibration and servicing the
GC/MS system. Analyze the failed extract in a subsequent Analysis Batch. If the repeat analysis meets
the surrogate recovery criterion, report only data for the reanalyzed extract. If the repeat analysis fails
the 70 to 130% recovery criterion after corrective action, extraction of the sample must be repeated
provided a sample is available and still within the holding time. If the re-extracted sample also fails the
recovery criterion, or if a duplicate field sample is not available, qualify all data for that sample as
"suspect-surrogate recovery."
9.3.7 Laboratory Fortified Sample Matrix (LFSM)
Within each Extraction Batch, analyze a minimum of one LFSM. The background concentrations of the
analytes in the sample matrix must be determined in a separate field sample and subtracted from the
measured values in the LFSM. If various sample matrixes are analyzed regularly, for example, drinking
16
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water processed from ground water and surface water sources; collect performance data for each
source.
93,, 7.1 Prepare the LFSM
Prepare the LFSM by fortifying a Field Duplicate with an appropriate amount of the analyte PDS
(Sect. 7.6.3) and surrogate PDS (Sect. 7.6.2). Generally, select a spiking concentration that is greater than
or equal to the native concentration for most analytes. Selecting a duplicate aliquot of a sample that has
already been analyzed aids in the selection of an appropriate spiking level. If this is not possible, use
historical data when selecting a fortifying concentration.
3.3. 7.2 Calculate the Percent Recovery
Calculate the percent recovery (%R) using the equation:
04 -B)
%R = X 100
(j
Where,
A = measured concentration in the fortified sample,
B = measured concentration in the unfortified sample, and
C = fortification concentration.
In order to obtain meaningful percent recovery results, correct the measured values in the LFSM and
LFSMD for the native levels in the unfortified samples, even if the native values are less than the MRL.
3.3. 7.3 Evaluate Analyte Recovery
Recoveries for analytes fortified at concentrations near or at the MRL (within a factor of two times the
MRL concentration) must be within plus or minus 50% of the true value. Recoveries for analytes fortified
at all other concentrations must be within plus or minus 30% of the true value. If the accuracy for any
analyte falls outside the designated range, and the laboratory performance for that analyte is shown to
be in control in the CCCs and in the LFB, the recovery is judged matrix biased. Report the result for the
corresponding analyte in the unfortified sample as "suspect-matrix."
9.3.8 Field Duplicate or Laboratory Fortified Sample Matrix Duplicate (FD or LFSMD)
Within each Extraction Batch, analyze a minimum of one Field Duplicate or one Laboratory Fortified
Sample Matrix Duplicate. If the method analytes are not routinely observed in field samples, analyze an
LFSMD rather than an FD.
9.3.8.1 Calculate the RPDfor Field Duplicates
Calculate the relative percent difference (RPD) for duplicate measurements (FD1 and FD2) using the
equation:
|FD1-FD2|
9.3,3.2 Acceptance Criterion for Field Duplicates
RPDs for Field Duplicates must be plus or minus 30% for each analyte. Greater variability may be
observed when Field Duplicates have analyte concentrations that are near or at the MRL (within a factor
of two times the MRL concentration). At these concentrations, Field Duplicates must have RPDs that are
plus or minus 50%. If the RPD of an analyte falls outside the designated range, and the laboratory
performance for the analyte is shown to be in control in the CCC and in the LFB, the precision is judged
17
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matrix influenced. Report the result for the corresponding analyte in the unfortified sample as "suspect-
matrix."
9.3.8.3 Calculate the RPDfor the LFSM and LFSMD
If an LFSMD is analyzed instead of a Field Duplicate, calculate the RPD using the equation:
\LFSMD-LFSM\
RPD = (LFSMD + LF5M)/2X10°
9.3.3.4 Acceptance Criterion for Fortified Matrix
RPDs for duplicate LFSMs must be plus or minus 30% for each analyte. Greater variability may be
observed when the matrix is fortified at analyte concentrations near or at the MRL (within a factor of
two times the MRL concentration). LFSMs at these concentrations must have RPDs that are plus or
minus 50%. If the RPD of an analyte falls outside the designated range, and the laboratory performance
for the analyte is shown to be in control in the CCC and in the LFB, the precision is judged matrix
influenced. Report the result for the corresponding analyte in the unfortified sample as "suspect-
matrix."
9.3.9 Retention Time Shifts
If QC failures are associated with retention time shifts in a sample, residual water in the extract may be
the cause of the failed QC. In this case, re-extract the sample and increase the time devoted to drying
the SPE cartridge with nitrogen.
9.3.10 Quality Control Sample (QCS)
A QCS (as defined in Sect. 3.14) must be analyzed during the IDC, and then at least quarterly thereafter.
Prepare the QCS in the elution solvent near the midpoint of the calibration range. The acceptance
criterion for the QCS is plus or minus 20% of the true value. If the accuracy for any analyte fails the
recovery criterion, prepare fresh standard dilutions and repeat the QCS evaluation.
9.4 Method Modification QC Requirements
The analyst is permitted to modify the GC injection technique, GC column and conditions, and MS
conditions. Any proposed method modifications must retain the basic chromatographic elements of this
method (Sect. 2). Examples of method modifications include alternate GC column phases, MS
conditions, quantitation ions, and additional QC analytes proposed for use with the method. The
following are required after a method modification.
9.4.1 Repeat the IDC
Establish an acceptable initial calibration (Sect. 10.2) using the modified conditions. Repeat the
procedures of the IDC (Sect. 9.2).
9.4.2 Document Performance in Representative Sample Matrixes
The analyst is also required to evaluate and document method performance for the proposed
modifications in real matrixes that span the range of waters that the laboratory analyzes. This additional
step is required because modifications that perform acceptably in the IDC, which is conducted in reagent
water, could fail ongoing method QC requirements in real matrixes. This is particularly important for
methods subject to matrix effects, such as GC/MS-based methods. For example, a laboratory may
routinely analyze drinking water from municipal treatment plants that process ground water, surface
water, or a blend of surface and ground water. In this case, the method modification requirement could
be accomplished by assessing precision (Sect. 9.2.2) and accuracy (Sect. 9.2.3) in a surface water with
18
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moderate to high total organic carbon (e.g., 2 mg/L or greater) and a hard ground water (e.g., 250 mg/L
as calcium carbonate (CaCO3) equivalent, or greater).
9.4.3 Monitor Performance of the Modified Method
The results of Section 9.4.1 and Section 9.4.2 must be appropriately documented by the analyst and
independently assessed by the laboratory's QA officer prior to analyzing field samples. When
implementing method modifications, it is the responsibility of the laboratory to review the results of
ongoing QC, and in particular, the results associated with LFSM, duplicate samples, CCCs, and the
internal standard area counts. If repeated failures are noted, the modification must be abandoned.
Demonstration and documentation of acceptable mass spectrometer tune and initial calibration is
required before performing the IDC and prior to analyzing field samples. The MS Tune Check and initial
calibration must be repeated each time a major instrument modification is made, or maintenance is
performed.
10.1 GC/MS Optimization
Any type of MS may be used as described in Sect. 6.15.5. Data presented in Section 17 were obtained in
the SIM mode using a quadrupole mass analyzer. Operation of the MS in selected ion monitoring mode
enhances sensitivity; however, less qualitative data are obtained for the method analytes and any
potential interferences. Because of this, and because the selected ions for the compounds of interest
are low masses that are likely to occur more frequently in interferences than most higher mass ions, the
analyst should also rely on chromatographic resolution to reduce the possibility of false positives. It is
recommended to use a GC column that is at least 30 m in length, with sufficient capacity to separate the
least retained analytes from the extraction solvent, and that provides adequate separation of the
compounds of interest from possible interferences.
10.1.1 MS Tune and MS Tune Check
Calibrate the mass and abundance scales of the MS using calibration compounds and procedures
recommended by the manufacturer with any modifications necessary to meet tuning requirements.
Introduce BFB (Sect. 7.7.4) into the GC/MS system. Acquire a mass spectrum using a scan range of
m/z 35-260. Use a single spectrum at the apex of the BFB peak, an average spectrum of the three
highest points of the peak, or an average spectrum across the entire peak to evaluate the performance
of the system. Appropriate background subtraction is allowed; however, the background scans must be
chosen from the baseline prior to, or after, elution of the BFB peak. If the BFB mass spectrum does not
meet all criteria in Section 17, Table 1. the MS must be re-tuned to meet these criteria before
proceeding with the initial calibration.
10.1.2 GC Conditions
Establish GC operating conditions appropriate for the GC column dimensions by optimizing the inlet
conditions and temperature program. GC conditions used during method development are summarized
in Section 17, Table 2. Tailing peak profiles are expected for 1-butanol, 2-propen-l-ol and, especially,
2-methoxyethanol. However, the column and inlet conditions chosen should not cause peaks to split or
broaden. The authors obtained acceptable results for this method as illustrated by the profiles in the
reconstructed ion chromatogram (Sect. 17, Figure 2) and in the extracted ion current profiles (EICPs)
(Sect. 17, Figure 3). Optimize chromatographic resolution such that a unique quantitation ion is available
19
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for each analyte that is free from interference due to an identical fragment ion in any co-eluting (or
overlapping) peaks.
10.1.3 SIM MS Conditions
Choose one primary quantitation ion and at least one confirmation ion. If possible, select a second
confirmation ion. Additional ions may be monitored that demonstrate a unique fragment in the mass
spectrum. Verify that the primary ion is free from interference due to an identical fragment ion in any
overlapping peaks. If the chromatogram is divided into SIM windows (also termed segments or periods),
the laboratory must ensure that each method analyte elutes entirely within the assigned window during
each Analysis Batch. Make this observation by viewing the mass chromatogram of the quantitation ion
for each analyte in the CCCs analyzed during an Analysis Batch. The entire Analysis Batch is invalid if one
or more analyte peaks drift outside of designated SIM windows in any CCC.
10.1.4 Suggested Ions and Dwell Times
Section 17, Table 3 lists ions used for quantitation and confirmation during method development. Set
the dwell time for each ion to acquire at least seven to 10 scans across each chromatographic peak. SIM
windows and dwell times used to collect method performance data are included in Table 3.
10,2 Initial Calibration
An initial calibration requires optimizing GC/MS conditions and confirming that the instrument meets
the BFB tune check criteria (Section 10.1.1). Calibration must be performed using peak areas and the
internal standard technique. Calibration using peak heights and external standard calibration are not
permitted.
10.2.1 Calibration Standards
Prepare a set of at least six calibration standards as described in Section 7.7. The lowest concentration
of the calibration standards must be at, or below, the MRL The MRL must be confirmed using the
procedure outlined in Section 9.2.4 after establishing the initial calibration. Additionally, field samples
must be quantified using a calibration curve that spans the same concentration range used to collect the
IDC data, e.g., analysts are not permitted to use a restricted calibration range to meet the IDC criteria
and then use a larger dynamic range during analysis of field samples.
10.2.2 Calibration Curve
Calibrate the GC/MS system using peak areas and the internal standard technique. Fit the calibration
points with either a linear or a quadratic regression (response vs. concentration). Weighting may be
used. The GC/MS instrument used during method development was calibrated using quadratic curves
with no weighting. Because the surrogate analytes are added at a single concentration level to the
calibration standards, calibrate for each surrogate using an average response factor. Suggested internal
standard assignments and quantitation ions for each method analyte are presented in Section 17,
Table3.
10.2.3 Calibration Acceptance Criteria
Evaluate the initial calibration by calculating the concentration of each analyte as an unknown against its
regression equation. For calibration levels that are less than or equal to the MRL, the result for each
analyte should be within plus or minus 50% of the true value. All other calibration points should
calculate to be within plus or minus 30% of their true value. If these criteria cannot be met, the analyst
could have difficulty meeting ongoing QC criteria. In this case, corrective action is recommended such as
reanalyzing the calibration standards, restricting the range of calibration, or performing instrument
20
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maintenance. If the cause for failure to meet the criteria is due to contamination or standard
degradation, prepare fresh calibration standards and repeat the initial calibration.
10,3 Continuing Calibration Checks (CCCs)
Analyze a CCC to verify the initial calibration at the beginning of each Analysis Batch, after every tenth
field sample, and at the end of each Analysis Batch. The beginning CCC for each Analysis Batch must be
at, or below, the MRL. This CCC verifies instrument sensitivity prior to the analysis of samples. Alternate
subsequent CCCs between the remaining calibration levels. Verify that the CCC meets the following
criteria.
10.3.1 Internal Standard Responses
The absolute area of the quantitation ion for each internal standard (l,4-dioxane-dg and chlorobenzene-
d5) must be within plus or minus 50% from the average area measured during the initial calibration. If
these limits are exceeded, corrective action is necessary (Sect. 10.4).
10.3.2 Surrogate Analytes
The calculated concentration of the surrogate analytes must be within plus or minus 30% of the true
value. If the surrogate analytes fail this criterion, corrective action is necessary (Sect. 10.4).
10.3.3 Method Analytes
Calculate the concentration of each method analyte in the CCC. Each analyte fortified at a level less than
or equal to the MRL must calculate to be within plus or minus 50% of the true value. The calculated
concentration of the method analytes in CCCs fortified at all other levels must be within plus or minus
30%. If these limits are exceeded, then all data for the failed analytes must be considered invalid. Any
field samples analyzed since the last acceptable CCC that are still within holding time must be reanalyzed
after an acceptable calibration has been restored.
10.4 Corrective Action
Failure to meet calibration performance criteria requires corrective action. Acceptable method
performance may be restored simply by servicing the GC injection port and clipping the column.
Following this and other minor corrective action, check the calibration with a mid-level CCC and a CCC at
the MRL, or recalibrate according to Section 10.2. If internal standard and calibration failures persist,
maintenance may be required, such as servicing the MS system and replacing the GC column. These
latter measures constitute major maintenance, and the analyst must return to the initial calibration step
(Sect. 10.2) and verify sensitivity by analyzing a CCC at, or below, the MRL.
11 Prcceduie
This section describes the procedures for sample preparation and analysis. Important aspects of this
analytical procedure include proper sample collection and storage (Sect. 8), ensuring that the
instrument is properly calibrated (Sect. 10). and that all required QC elements are included (Sect. 9.3).
For this method, the volume of nitrogen required to dry SPE cartridges must be determined prior to
conducting this procedure. Refer to Section 9.1 for guidance on determining this volume.
11.1 Sample Preparation
All field and QC samples must contain the preservatives listed in Section 8.1. including the LRB and LFB.
21
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11.1.1 QC Samples
With each Extraction Batch (Sect. 3.4). include one LRB, one LFB, and one LFSM. One FD, or one LFSMD,
is required. Refer to Section 9.3 for the frequency of QC elements. Fortify the LFB, LFSM, and LFSMD,
with an appropriate volume of analyte PDS (Sect. 7.6.3).
11.1.2 Surrogate Analytes
Add an aliquot of the surrogate PDS (Sect. 7.6.2) to each sample. Cap and mix the samples. For method
development work, a 10 ul aliquot of the 50 u.g/mL surrogate PDS was added to 0.050 L in the original
sample bottle for a final concentration of 10 u.g/L.
11.2 Extraction Procedure Using Waters AG-2 SPE Format
11.2.1 Set up the Extraction Manifold
Place extraction cartridges on the SPE vacuum manifold and attach 3 mL polypropylene reservoirs.
Establish a vacuum between -8 and -5 psig.
11.2.2 Cartridge Cleaning
Add 3 mL of 5% methanol in DCM to each reservoir and draw enough solvent through the cartridge to
soak the sorbent. Allow the sorbent to soak for approximately one minute. Draw the remaining solvent
to waste until the cartridge is dry. Repeat this step with 2 mL of purge-and-trap-grade methanol.
11.2.3 Cartridge Conditioning
11.2.3.1 Condition with Methanol
Add approximately 2 mL of methanol to the reservoir and draw enough solvent through the cartridge to
soak the sorbent. Allow the sorbent to soak for approximately one minute. Draw the solvent through
the cartridge; aspirate, but do not allow the sorbent to dry completely. It is not necessary to leave a
solvent layer above the sorbent bed.
11.2.3.2 Condition with Water
Fill the 3 mL reservoir completely with reagent water. Draw the water through the cartridge, but do not
allow the sorbent to dry completely. It is not necessary to leave a water layer above the sorbent bed.
Remove the 3 mL reservoir. The AC-2 cartridges are now ready for sample loading.
11.2.4 Sample Loading
Attach 60 mL reservoirs to the SPE cartridges. Load samples at a flow rate of 5 mL/min or less using a
vacuum between -8 and -5 psig. Approximate this rate by ensuring that individual drops are observed
exiting the delivery tubes and by timing this step. Rinse the empty sample bottles with 5 mL of reagent
water and add the rinse to the reservoir. After the sample passes completely through the cartridge,
aspirate for approximately 30 seconds; close the manifold valve. After all samples are loaded, remove
the 60 mL reservoirs and increase the vacuum to approximately 20 psig in preparation for the drying
steps.
11.2.5 Cartridge Drying
The drying steps are very important. Precisely repeat the procedure optimized during the IDC.
11.2.5.1 Methanol Rinse Step
Attach a clean, dry 3 mL reservoir to each cartridge. Add 150 ul of methanol to each reservoir. Aspirate
at full vacuum for approximately 30 seconds. Remove the reservoirs and set aside for later use during
the elution step.
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11.2.5.2 Nitrogen Purge Step
Transfer the cartridges to the drying manifold. Do not attach the drying manifold to the lid of the
extraction manifold. Dry with high-purity nitrogen or zero air using the flow rate and duration optimized
during the IDC. Use the rotameter to monitor the flow rate.
11.2.5.3 Drying Manifold Valves
Remove residual water from the manifold valves while the cartridges are drying. Open the valves and
transfer a few milliliters of methanol to the top of each valve. Pull air through the valves under full
vacuum. Do not omit this step. The manifold valves and delivery tubes hold enough water to cause
retention time shifts when analyzing the final extract.
11.3 Extraction Procedure using UCT EU-541 SPE Format
11,3,1 Set Up the Extraction Manifold
Place extraction cartridges on the SPE vacuum manifold. Establish a vacuum between -8 and -5 psig.
11,3,2 Cartridge Cleaning
Fill each cartridge with 5% methanol in DCM and draw enough solvent through the cartridge to soak the
sorbent. Allow the sorbent to soak for approximately one minute. Draw the remaining solvent to waste
until the cartridge is dry. Repeat this step with 2 ml of purge-and-trap-grade methanol.
11,3,3 Cartridge Conditioning
11,3.3,1 Condition with Methanol
Add approximately 2 ml of methanol to each SPE cartridge and draw enough solvent through to soak
the sorbent. Allow the sorbent to soak for approximately one minute. Draw the solvent through the
cartridge; aspirate, but do not allow the sorbent to dry completely. It is not necessary to leave a solvent
layer above the sorbent bed.
11.3.3.2 Condition with Water
Fill each cartridge completely with reagent water. Draw the water through the cartridge, but do not
allow the sorbent to dry completely. Repeat this step a second time, but leave one to two ml of water
above the sorbent bed.
11,3,4 Sample Loading
Attach 60 ml reservoirs to the SPE cartridges using a tube adaptor (Sect. 6.11.1). Load samples at a flow
rate of 5 mL/min or less using a vacuum between -8 and -5 psig. Approximate this rate by ensuring that
individual drops are observed exiting the delivery tubes and by timing this step. Rinse the empty sample
bottles with 5 ml of reagent water and add the rinse to the reservoir. After the sample passes
completely through the cartridge, aspirate for approximately 30 seconds; close the manifold valve. After
all samples are loaded, remove the 60 ml reservoirs and increase the vacuum to approximately 20 psig
in preparation for the drying steps.
11,3,5 Cartridge Drying
The drying steps are very important. Precisely repeat the procedure optimized during the IDC.
11.3,5,1 Methanol Rinse Step
Add 200 u.L of methanol to the SPE cartridge with intent to rinse residual water droplets from the walls
of the cartridge. Any remaining water on the walls will be eliminated during the nitrogen-drying step.
Aspirate at full vacuum for approximately 30 seconds.
23
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11,3,5.2 Nitrogen Purge Step
Transfer the cartridges to the drying manifold. Do not attach the drying manifold to the lid of the
extraction manifold. Dry with high-purity nitrogen or zero air using the flow rate and duration optimized
during the IDC. Use the rotameter to monitor the flow rate.
11,3,5,3 Drying Valves
Remove residual water from the manifold valves while the cartridges are drying. Open the valves and
transfer a few milliliters of methanol to the top of each valve. Pull air through the valves under full
vacuum. Do not omit this step. The manifold valves and delivery tubes hold enough water to cause
retention time shifts when analyzing the final extract.
11.4 Cartridge Elution
When all valves are dry, release the vacuum on the extraction manifold and place 2 ml volumetric tubes
under each sample position. Return the dried cartridges to the same position on the manifold used
during sample loading. (Attach a dry, 3 ml reservoir to each Waters AC-2 cartridge. It is not necessary to
reverse the cartridges.) Measure approximately 2.3 ml of elution solvent and add this volume to each
reservoir. Soak each cartridge for 1 minute then elute in a slow, dropwise manner. Aspirate each
cartridge completely. The extracts should not have a visible water layer. Typically, approximately 1.8 ml
of elution solvent is recovered.
11.5 Internal Standard Addition
Add an aliquot of the internal standard PDS (Sect. 7.6.1) to each extract. For method development work,
a 10 u.L aliquot of the 50 u.g/mL internal standard PDS was added to each 2 ml extract for a final
concentration of 0.25 u.g/mL Bring each extract to volume with the 5% methanol in DCM elution
solvent.
11.6 Extract Drying
Add approximately 2 cm3 of sodium sulfate directly to the 2 ml volumetric tube. Estimate this volume of
salt by filling the 2 ml volumetric until the solid level reaches just under or at the 2 ml mark. The liquid
level will rise close to the ground glass section of the volumetric, but should not overflow. Stopper
securely and vortex for 10 seconds. Allow the desiccant to remain in contact with the solvent for
15 minutes. Using a disposable pipette, transfer the supernatant to a 2 ml autosampler vial. (Condition
the sodium sulfate at 400 °C for four hours just prior to use with this method. Repeat the conditioning
process at least once per month and more frequently in humid weather.)
11.7 Analysis of Sample Extracts
Establish GC/MS operating conditions per the guidance in Section 10.1. Analyze an archived, unfortified
extract to condition the GC inlet and column. This step is optional; however, the authors believe it is an
expedient means of "conditioning" the analytical system, especially after maintenance or an extended
period of disuse. Establish a valid initial calibration following the procedures in Section 10.2 or confirm
that the existing calibration is still valid by analyzing a low-level CCC. If establishing an initial calibration
for the first time, complete the IDC prior to analyzing field samples. Analyze field and QC samples in a
properly sequenced Analysis Batch as described in Section 11.8.
11.8 The Analysis
An Analysis Batch is a sequence of samples that is analyzed on the same instrument during a 24 hour
period that begins and ends with the analysis of CCCs. The Analysis Batch must not have more than 20
24
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field samples. QC samples, such as the LRB, LFB, FD, LFSM, and LFSMD, are not counted as part of the
20-sample limit. The purpose of the field sample limit is to ensure that a low-level CCC and an LRB are
repeated on a regular and frequent basis. Analytical conditions for the Analysis Batch must be the same
as those applied during calibration.
11.8.1 Initial CCC
After a valid calibration is established, begin every Analysis Batch by analyzing a low-level CCC at, or
below, the MRL The calculated concentration of the method analytes in this CCC must be within plus or
minus 50% of the true value. The calculated concentration of the surrogate analytes must be within plus
or minus 30%. The initial CCC must pass the plus or minus 50% internal standard area criterion
(Sect. 10.3.1). The initial CCC confirms that the calibration curve is valid.
11.3.2 Field and QC Samples
After the initial CCC, continue the Analysis Batch by analyzing an LRB, followed by field and QC samples.
11.8.3 CCC Frequency
Analyze a mid- or high-level CCC after every tenth field sample. QC samples, such as the LRB, LFB, FD,
LFSM, and LFSMD, are not counted when determining the required frequency of CCCs.
11.8.4 Final CCC
The last injection of the Analysis Batch must be a mid- or high-level CCC. The acquisition start time of the
final CCC must be within 24 hours of the acquisition start time of the low-level CCC at the beginning of
the Analysis Batch. More than one Analysis Batch within a 24 hour period is permitted. An Analysis
Batch may contain field and QC samples from multiple extraction batches.
11.8.5 Initial Calibration Frequency
A full calibration curve is not required before starting a new Analysis Batch. A previous calibration can be
confirmed by running an initial, low-level CCC followed by an LRB. If a new calibration curve is analyzed,
an Analysis Batch run immediately thereafter must begin with a low-level CCC and an LRB.
12 Data Analysis and Calculations
12,1 Establish Retention Time Windows
Select an appropriate retention time window for each analyte to identify them in QC and field sample
chromatograms. Base this assignment on measurements of actual retention time variation for each
compound in standard solutions analyzed on the GC/MS over the course of time. The suggested
variation is plus or minus three times the standard deviation of the retention time for each compound
for a series of injections. The injections from the initial calibration and from the IDC may be used to
calculate the retention time window. However, the experience of the analyst should weigh heavily on
the determination of an appropriate range.
12.2 Identify Analytes by Retention Time
Initially, identify each analyte by comparison of its retention time with that of the corresponding analyte
peak in a recent initial calibration standard or CCC. Use the same software settings established during
the calibration procedure and the predetermined retention time windows.
12.3 Confirm Analyte Identifications
Examine the SIM spectrum for each analyte. Use appropriate background subtraction to remove ions
contributed by co-eluting matrix components. For each analyte identified by retention time, at least one
25
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confirmation ion must be present. The abundance of the confirmation ions relative to the quantitation
ion should agree within an absolute 20 percent of the relative abundance in the spectrum taken from a
recent calibration standard. For example, if an ion has a relative abundance of 30 percent in the
calibration standard, its abundance in the sample spectrum should be in the range of 10 to 50 percent.
Only confirmation ions that exhibit greater than 30% relative abundance to the quantitation ion in the
mass spectrum of the calibration standard must meet this criterion. Knowledge of sample history and
the experience of the analyst are important factors that may aid analyte confirmation.
12.4 Compound Quantitation
Calculate analyte concentrations using the multipoint calibration. Report only those values that fall
between the MRL and the highest calibration standard. Calculations should be rounded to an
appropriate number of significant figures, typically two, but not more than three. Do not base
quantitation of samples on response factors calculated from CCCs.
12.5 Data Review
Prior to reporting data, the chromatograms must be reviewed for incorrect peak identification or
improper integration. Prior to reporting data, the laboratory is responsible for verifying that QC
requirements have been met and that any appropriate qualifier is assigned.
12.6 Exceeding the Calibration
The analyst must not extrapolate beyond the established calibration range. If an analyte result exceeds
the range of the initial calibration curve, dilute the extract with elution solvent containing the required
concentration of internal standards. Re-inject the diluted sample. Incorporate the dilution factor into
final concentration calculations. The resulting data must be annotated as a dilution, and the reported
MRLs must reflect the dilution factor. Report surrogate recoveries observed in the undiluted sample.
13 Performance
13.1 Precision, Accuracy, LCMRL Results
Tables for these data are presented in Section 17. LCMRLs are presented for each of two SPE formats:
Waters AC-2, 400 mg cartridges (Table 4) and UCT EU-541, 600 mg cartridges (Table 8). For each of these
formats, single-laboratory precision and accuracy data are presented for three water matrixes: reagent
water (Waters AC-2: Table 5 and UCT EU-541: Table 9), finished ground water (Waters AC-2: Table 6 and
UCT EU-541: Table 10). and finished surface water (Waters AC-2: Table 7 and UCT EU 541: Table 11).
Figure 4 and Figure 5 are reconstructed ion chromatograms of extracts (Waters AC-2 format) obtained
from drinking water using the GC/MS conditions employed during method development.
13.2 Analyte Stability Study
Chlorinated (finished) surface water samples were inoculated with diluted, microbial-rich water from an
ambient source, and fortified with 0.80 u.g/L of 1,4-dioxane and 4.0 u.g/L of 2-propen-l-ol, 1-butanol and
2-methoxyethanol. These samples were preserved and stored as required in this method. The percent
change from the initial analyzed concentration observed after 7, 14, 21, and 28 days is presented in
Section 17, Table 12.
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13.3 Extract Storage Stability
Extract storage stability studies were conducted on extracts obtained from chlorinated surface water
fortified with the method analytes (Sect. 13.2). The percent change from the initial analyzed
concentration observed after 7', 14, 21, and 28 days storage is presented in Section 17, Table 13.
14 Pollution Prevention
For information about pollution prevention applicable to laboratory operations described in this
method, consult: Less is Better, Guide to Minimizing Waste in Laboratories, a web-based resource
available from the American Chemical Society at www.acs.org.
15 Vv'-i '• M-IIH c 'i i ' t
The Agency requires that laboratory waste management practices be consistent with all applicable rules
and regulations, and that laboratories protect the air, water, and land by minimizing and controlling all
releases from fume hoods and bench operations. In addition, compliance is required with any sewage
discharge permits and regulations, particularly the hazardous waste identification rules and land
disposal restrictions.
16
1. US EPA Document # 815-R-05-006, "Statistical Protocol for the Determination of the Single-
Laboratory Lowest Concentration Minimum Reporting Level (LCMRL) and Validation of Laboratory
Performance at or Below the Minimum Reporting Level (MRL)", Office of Water, November 2004.
2. US EPA Document # EPA 815-R-11-001, "Technical Basis for the Lowest Concentration Minimum
Reporting Level (LCMRL) Calculator", Office of Water, December 2010.
27
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17 Tables, Figures, and Method performance Data
Table 1. 4-Bromofluorobenzene (BFB) Mass Intensity Criteria
m/z
95
96
173
174
175
176
177
Required Intensity (relative abundance)
Base peak, 100% relative abundance
5 to 9% of m/z 95
Less than 2% of m/z 174
Greater than 50% of m/z 95
5 to 9% of m/z 174
Greater than 95% but less than 105% of m/z 174
5 to 10% of m/z 176
Table 2. Gas Chromatography/Mass Spectrometry (GC/MS) Conditions
Parameter
Column
Inlet liner
Inlet conditions
Injection volume
Column flow rate
GC temperature program
Solvent delay
MS source temperature
MS quadrupole
temperature
GC/MS interface
Conditions3
Phenomenex (Torrance, CA) ZB-WAX p/t/s: 30 meter, 0.25 mm i.
u.m film thickness (df)
4-mm i.d., single-gooseneck, deactivated glass with deactivated
wool
d., 0.5
glass
200 °C, pulsed splitless injection mode: 10 psig until 0.5 minutes, purge
flow (split) on at 0.5 minutes @ 100 mL/min
1 u.L using a 10 ul syringe
0.9 mL/min in constant flow mode, helium carrier gas
30 °Cfor 0.5 min, 10 °C/min to 110 °C, hold 0 min, 25 °C/min to
hold 6 min
200 °C,
9.8 min before activating filaments in the electron impact source
230 °C
150 °C
Direct, 200 °C
a. The chromatograms presented in Figures 2-5 were obtained under these conditions.
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TableS. Retention Times, Quantitation Ions, and Internal Standard Assignments3
Analyte
Filament delay
Internal standard (IS):
1,4-dioxane-ds
SIM Window
(minutes)
RTb
Q-lonc
Confirmation
lonsc
9.8-10.6
10.29
64,46
1,4-dioxane
9.8-10.6
10.31
88
87, 58, 57
1,4-dioxane-ds
Surrogate: 2-propen-l-ol-ds
10.6-12.1
11.16
61°
63,46
chlorobenzene-ds
2-propen-l-ol
10.6-12.1
11.26
57
58, 55, 39
chlorobenzene-ds
Surrogate: l-butanol-d:
10
10.6-12.1
11.71
64
63, 50, 46
chlorobenzene-ds
1-butanol
10.6-12.1
11.87
56
55, 43, 41
chlorobenzene-ds
2-methoxyethanol
12.1-22.5
12.50
45
76, 47, 58
chlorobenzene-ds
Internal standard:
chlorobenzene-ds
12.1-22.5
13.14
117
76, 119
a. These quantitation ions are appropriate for the column used to generate method performance data.
See Figures 2-5 for reconstructed ion chromatograms (RICs) and extracted ion current profiles
(EICPs) obtained during collection of the method performance data.
b. RT = retention time observed using Phenomenex Zebron ZB-WAX plus column.
c. Dwell times vary between 20 and 40 ms.
d. This mass corresponds to C3D4HO+- rather than the expected fragment, C3D5O+-, m/z 62.
Table 4. LCMRL Results for the Waters AC-2 SPE Format3
Analyte
1,4-dioxane
2-propen-l-ol
1-butanol
2-methoxyethanol
LCMRL Fortification Levels (ng/L)
0.0, 0.040, 0.070, 0.10, 0.20, 0.30, 0.40, 0.50
0.0, 0.20, 0.35, 0.50, 1.0, 1.5, 2.0, 2.5
0.0, 0.20, 0.35, 0.50, 1.0, 1.5, 2.0, 2.5
0.0, 0.20, 0.35, 0.50, 1.5, 1.0, 2.0, 2.5
Calculated LCMRL (ng/L)
0.074
0.30
0.44
0.37
a. LCMRL = lowest concentration minimum reporting limit; SPE = solid phase extraction.
Table 5. Precision and Accuracy Data for Reagent Water: Waters AC-2 SPE Format3
Analyte
1,4-dioxane
2-propen-l-ol
1-butanol
2-methoxyethanol
Surrogate:
2-propen-l-ol-de
Surrogate:
1-butanol-dio
Fortification
(Hg/L)b
0.40
2.0
2.0
2.0
10
10
Mean %RC
(n=7)
102
88.1
97.0
93.3
92.6
95.5
%RSDC
3.9
4.4
2.6
3.0
3.3
2.3
Fortification
(Hg/L)
8.0
40
40
40
10
10
Mean %R
(n=5)
96.8
90.8
92.2
92.4
92.2
92.7
%RSD
2.0
1.1
1.8
1.6
0.94
1.1
a. SPE = solid phase extraction.
b. The MRL was confirmed at these concentrations during collection of the method performance data.
c. %R = percent recovery; %RSD = percent relative standard deviation.
29
-------
Table 6. Precision and Accuracy Data for Ground Water: Waters AC-2 SPE Format3
Analyte
1,4-dioxane
2-propen-l-ol
1-butanol
2-methoxyethanol
Surrogate:
2-propen-l-ol-de
Surrogate:
1-butanol-dio
Fortification
(Hg/L)b
0.40
2.0
2.0
2.0
10
10
Mean %Rc-d
(n=5)
104
93.0
86.4
83.3
93.5
95.1
%RSDd
3.0
2.7
1.8
1.2
2.3
1.7
Fortification
(Hg/L)
8.0
40
40
40
10
10
Mean %RC
(n=5)
98.5
92.5
92.3
92.8
93.1
92.7
%RSD
2.2
2.4
2.0
2.0
1.5
1.7
a. Ground water physical parameters: pH = 7.8; total hardness = 337 mg/L (as CaCO3); free chlorine =
0.60 mg/L, total chlorine = 0.86 mg/L; SPE = solid phase extraction.
b. The MRL was confirmed at these concentrations during collection of the method performance data.
c. Recoveries corrected for native levels in the unfortified matrix.
d. %R = percent recovery; %RSD = percent relative standard deviation.
Table 7. Precision and Accuracy Data for Surface Water: Waters AC-2 SPE Format3
Analyte
1,4-dioxane
2-propen-l-ol
1-butanol
2-methoxyethanol
Surrogate:
2-propen-l-ol-de
Surrogate:
1-butanol-dio
Fortification
(Hg/L)b
0.40
2.0
2.0
2.0
10
10
Mean %Rc'd
(n=5)
94.1
87.6
79.0
86.6
88.0
87.5
%RSDd
3.2
1.2
3.1
2.8
1.2
2.4
Fortification
(M8/L)
8.0
40
40
40
10
10
Mean %RC
(n=5)
93.0
89.1
87.7
89.2
88.9
88.6
%RSD
4.3
3.7
3.4
3.8
2.9
2.8
a. Surface water physical parameters: pH = 7.3; total organic carbon (TOC) = 2.28 mg/L; free chlorine =
1.06 mg/L, total chlorine = 1.51 mg/L; SPE = solid phase extraction.
b. The MRL was confirmed at these concentrations during collection of the method performance data.
c. Recoveries corrected for native levels in the unfortified matrix.
d. %R = percent recovery; %RSD = percent relative standard deviation.
Table 8. LCMRL Results for the UCT EU-541 SPE Format3
Analyte
1,4-dioxane
2-propen-l-ol
1-butanol
2-methoxyethanol
LCMRL Fortification Levels (ng/L)
0, 0.048, 0.070, 0.10, 0.20, 0.30, 0.40, 0.48
0, 0.16, 0.24, 0.35, 0.50, 1.0, 1.5, 2.0, 2.4
0, 0.24, 0.35, 0.50, 1.0, 1.5, 2.0, 2.4
0, 0.24, 0.35, 0.50, 1.0, 1.5, 2.0, 2.4
Calculated LCMRL (ng/L)
0.090
0.17
0.61
0.30
a. LCMRL = lowest concentration minimum reporting limit; SPE = solid phase extraction.
30
-------
Table 9. Precision and Accuracy Data for Reagent Water: UCT EU-541 SPE Format3
Analyte
1,4-dioxane
2-propen-l-ol
1-butanol
2-methoxyethanol
Surrogate:
2-propen-l-ol-de
Surrogate:
1-butanol-dio
Fortification
(Hg/L)b
0.40
2.0
2.0
2.0
10
10
Mean %RC
(n=5)
96.2
84.3
97.1
86.2
84.4
90.1
%RSDC
3.7
5.7
0.84
8.2
6.7
1.8
Fortification
(Hg/L)
8.0
40
40
40
10
10
Mean %R
(n=5)
93.7
86.7
91.8
86.4
87.4
92.3
%RSD
2.3
4.2
1.9
3.4
2.9
1.6
a. SPE = solid phase extraction.
b. The MRL was confirmed at these concentrations during collection of the method performance data.
c. %R = percent recovery; %RSD = percent relative standard deviation.
Table 10. Precision and Accuracy Data for Ground Water: UCT EU-541 SPE Format3
Analyte
1,4-dioxane
2-propen-l-ol
1-butanol
2-methoxyethanol
Surrogate:
2-propen-l-ol-de
Surrogate:
1-butanol-dio
Fortification
(Hg/L)b
0.40
2.0
2.0
2.0
10
10
Mean %Rc'd
(n=5)
102
84.7
82.0
87.4
84.3
90.1
%RSDd
2.7
0.83
1.2
1.3
2.0
1.1
Fortification
(Hg/L)
8.0
40
40
40
10
10
Mean %RC
(n=5)
96.3
83.9
89.4
82.7
82.9
89.4
%RSD
4.9
0.96
2.4
1.5
2.0
2.5
a. Ground water physical parameters: pH = 7.8; total hardness = 337 mg/L (as CaCO3); free chlorine =
0.60 mg/L, total chlorine = 0.86 mg/L; SPE = solid phase extraction.
b. The MRL was confirmed at these concentrations during collection of the method performance data.
c. Recoveries corrected for native levels in the unfortified matrix.
d. %R = percent recovery; %RSD = percent relative standard deviation.
31
-------
Table 11. Precision and Accuracy Data for Surface Water: UCT EU-541 SPE Format3
Analyte
1,4-dioxane
2-propen-l-ol
1-butanol
2-methoxyethanol
Surrogate:
2-propen-l-ol-de
Surrogate:
1-butanol-dio
Fortification
(Hg/L)b
0.40
2.0
2.0
2.0
10
10
Mean %Rc-d
(n=5)
96.3
92.2
84.2
93.7
90.4
92.4
%RSDd
3.1
3.1
5.5
1.8
1.9
2.3
Fortification
(Hg/L)
8.0
40
40
40
10
10
Mean %RC
(n=5)
101
88.1
89.7
85.7
86.2
90.2
%RSD
5.0
1.0
2.1
1.2
1.4
1.6
a. Surface water physical parameters: pH = 7.3; total organic carbon (TOC) = 2.28 mg/L; free chlorine =
1.06 mg/L, total chlorine = 1.51 mg/L; SPE = solid phase extraction.
b. The MRL was confirmed at these concentrations during collection of the method performance data.
c. Recoveries corrected for native levels in the unfortified matrix.
d. %R = percent recovery; %RSD = percent relative standard deviation.
32
-------
Table 12. Aqueous3 Sample Holding Time Data (n=4)
Analyte
1,4-dioxane
2-propen-l-ol
1-butanol
2-methoxyethanol
Fortified
Cone. (ng/L)
0.80
4.0
4.0
4.0
Day Zero
Mean
(M8/L)
0.78
3.5
3.6
3.4
Day
Zero
%RSD
4.6
3.2
2.6
3.5
Day?
%Changeb
0.19
0.53
-1.5
-1.2
Day?
%RSD
3.7
2.0
2.2
2.6
Day 14
%Change
-1.8
-3.2
-8.1
-2.0
Day 14
%RSD
2.7
1.8
2.2
2.0
Day 21
%Change
-2.6
-3.7
-6.8
-0.47
Day 21
%RSD
4.2
2.2
4.2
3.7
Day 28
%Change
-0.59
-2.4
-4.8
0.24
Day 28
%RSD
6.0
3.5
4.2
2.8
a. Finished water from a surface water source. Physical parameters: pH = 7.3; total organic carbon (TOC) = 2.28 mg/L; free chlorine = 1.06
mg/L, total chlorine = 1.51 mg/L.
b. %Change = percent change from Day Zero calculated as follows: (Day X mean concentration - Day Zero mean concentration) / Day Zero
mean concentration * 100%, where X is the analysis day.
Table 13. Holding Time Data for Sample Extracts (n=4)
Analyte
1,4-dioxane
2-propen-l-ol
1-butanol
2-methoxyethanol
Fortified
Cone. (ng/L)
0.80
4.0
4.0
4.0
Day Zero
Mean
(M8/L)
0.76
3.4
3.4
3.4
Day
Zero
%RSD
2.7
1.8
2.2
2.0
Day?
%Changea
2.5
2.3
1.7
2.8
Day?
%RSD
5.9
2.3
2.4
2.7
Day 14
%Change
7.5
1.4
0.42
1.1
Day 14
%RSD
8.4
2.9
1.6
1.2
Day 21
%Change
1.9
0.35
1.9
2.5
Day 21
%RSD
4.9
2.4
2.4
2.6
Day 28
%Change
1.7
3.1
2.5
2.9
Day 28
%RSD
6.6
2.6
2.6
2.6
a. %Change = percent change from Day Zero calculated as follows: (Day X mean concentration - Day Zero mean concentration) / Day Zero
mean concentration * 100%, where X is the analysis day.
33
-------
Table 14. Initial Demonstration of Capability (IDC) Quality Control Requirements
Method
Reference
Section
9.1
Section
9.2.1
Section
9.2.2
Section
9.2.3
Section
9.2.4
Section
9.2.5
Requirement
Optimize SPE
cartridge drying
parameters
Demonstration
of low system
background
Demonstration
of precision
Demonstration
of accuracy
MRL
confirmation
Quality Control
Sample (QCS)
Specification and Frequency
For each extraction format
Analyze a Laboratory Reagent Blank
after the high calibration standard
during the IDC calibration.
Extract and analyze 5 replicate
Laboratory Fortified Blanks (LFBs)
near the mid-range concentration.
Calculate mean recovery for
replicates used in Section 9.2.2.
Fortify and analyze 7 replicate LFBs
at the proposed MRL concentration.
Confirm that the Upper Prediction
Interval of Results (PIR) and Lower
PIR meet the recovery criteria.
Analyze mid-level QCS.
Acceptance Criteria
Extract must be visibly dry. Retention
times must match those observed for
calibration standards.
Demonstrate that all method analytes
are less than one-third of the Minimum
Reporting Level (MRL).
Percent relative standard deviation
must be <20%.
Mean recovery within ±30% of the true
value.
Upper PIR <150%
Lower PIR >50%
Results must be within +20% of the
true value.
Table 15. Ongoing Quality Control Requirements
Method
Reference
Section
10.1.1
Section
10.2
Section
9.3.1
Requirement
Bromofluorobenzene
(BFB) Tune Check
Initial calibration
Laboratory Reagent
Blank (LRB)
Specification and Frequency
lUg/mL in elution solvent in full
scan mode with each initial
calibration, or after major mass
spectrometer service.
Use the internal standard
calibration technique to generate
a linear or quadratic calibration
curve. Use at least 6 standard
concentrations. Evaluate the
calibration curve as described in
Section 10.2.3.
Include one LRB with each
Extraction Batch. Analyze one LRB
with each Analysis Batch.
Acceptance Criteria
Table 1, Section 17
When each calibration standard is
calculated as an unknown using the
calibration curve, the lowest level
standard should be within ±50% of
the true value. All other points
should be within ±30% of the true
value.
Demonstrate that all method
analytes are below one-third the
Minimum Reporting Level (MRL),
and that possible interference from
reagents and glassware do not
prevent identification and
quantitation of method analytes.
34
-------
Method
Reference
Requirement
Specification and Frequency
Acceptance Criteria
Section Laboratory Fortified
9.3.3 Blank
Include one LFB with each
Extraction Batch.
For analytes fortified at
concentrations <2 x the MRL, the
result must be within ±50% of the
true value; ±30% of the true value if
fortified at concentrations greater
than 2 x the MRL
Section Continuing
10.3 Calibration Check
(CCC)
Verify initial calibration by
analyzing a low-level CCC at the
beginning of each Analysis Batch.
Subsequent CCCs are required
after every tenth field sample and
to complete the batch.
The lowest level CCC must be within
±50% of the true value. All other
points must be within ±30% of the
true value.
Section Internal standards
9.3.5 (IS)
Internal standards are added to all
standards and sample extracts.
Peak area counts for each IS must
be within ±30% of the area in the
most recent CCC, and ±50% of the
average peak area in the initial
calibration.
Section
9.3.6
Surrogate analytes
Surrogates are added to all field
samples and QC samples prior to
extraction.
70% to 130% recovery
Section Laboratory Fortified
9.3.7 Sample Matrix
(LFSM)
Include one LFSM per Extraction
Batch. Fortify the LFSM with
method analytes at a
concentration close to but greater
than the native concentrations (if
known).
For analytes fortified at
concentrations <2 x the MRL, the
result must be within ±50% of the
true value; ±30% of the true value if
fortified at concentrations greater
than 2 x the MRL.
Section Laboratory Fortified
9.3.8 Sample Matrix
Duplicate (LFSMD) or
Field Duplicate (FD)
Include at least one LFSMD or FD
with each Extraction Batch.
For LFSMDs or FDs, relative percent
differences must be <30% (<50% if
concentration <2 x the MRL).
Section QC failures
9.3.9 associated with
retention time shifts
Evaluate retention times for
analytes, surrogates, and internal
standards failing QC criteria.
Retention times of the method
analytes must be within the
windows determined using dry
calibration standards (Sect. 12.1).
SPE drying procedures must be
optimized for each extraction
format (Sect. 9.1).
Section
9.3.10
Quality Control
Sample (QCS)
Analyze a QCS at least quarterly.
Results must be ±20% of the true
value.
35
-------
Adjust flow rate
with needle valve.
If needle valve
installed, open m —
fully counter- [JH —
clockwise.
Flowmeter (rotam
n
— ' — 1
1/4" Teflon Tubing
N2, 80 psig
I
Waters AC-2
cartridges
T
UCT EU-541, 3-mL cartridges
with tube adaptors
Figure 1. Drying apparatus and proper placement of rotameter in flow path
36
-------
Abundance
34000 -_
32000 -_
30000 -_
28000 -_
26000 -_
24000 -_
22000 -J
20000 -j
18000 ^
16000 -_
14000 -^
12000 ^
10000 -_
8000 -j
6000 -
4000 -J
2000 -
s
s
o
°9
I
O
in
OJ
o
o
m 5
1 o.
o o
a
cvi
o
o
1
o
1-^
d
o
(B
X
o
I
!>
o
d
nme-> 10.00
15.00
20.00
Figure 2. Reconstructed ion chromatogram (RIC), SIM mode, for calibration standard
37
-------
0.25 |.ig/mL 1,4 dioxane-ds
0.020 [jg/mL 1,4-dioxane
0.25 |jg/mL 2-propen-1-ol-dfe
Abundance
9000-
sooo.
7000-
eooo.
5000-
4000-
3000-
3300'
1000
o.
Tmp-->
Ion 96 nci ri' . .. M 91 Of01401014.D\dalams
Ion 84.00 (63 70 to 64 70): 01 401 01 4 DVlatoms
ton 4600(4570(046.70] 01 401 01 4 D\dala.ms
10,262
M
r\l
I'll
j \
ff\\
}/ i \k_
n 'nn 1 n '?n i n '40
1
0.10 pg/mL 2-propen-1-ol
^ounaance
6000 -
4000 -
2000 -
0 -
rime-> 1 0
Ion 57. 00 (56 70 lo 57 70): 01401014.0Vdata.ms
Ion 58.00(57.701058.70): 0140lOl4.DVdata.rns
Ion 55.00(54.70105570): 01401014.DVdata.ms
Ion 39.00(38.70lo39.70): Ol401014.DVdata.ms
11.284
^^S* '
wL
86 1 1 .35
0.10 Md/rnL 2-methoxyethanol
12000 -
10000 -:
8000 -
6000 -
4000 -
2000 -
0 -
ime--* 1 2
Ion 45.00(44.701045.70): 014010l4.DVdatams
Ion 47.00 (46 70 to 47.70): 01401014.0Vdalams
Ion 58.00(57701058.70): 01401014.0Vdatams
Ion 76,00(75.701076.70): 014010l4.DVdaiams
12.490
A
l^
28 1256
HDimaance |0n 88.00 (87.70 to 88.70): 01401014.DVdata.ms
Ion 87.00 (86.70 to 87.70): 014010H.DVdala.ms
1000 -
800 -
600 -
400 -
200 -
0 -
Ion 58.00(57.70!o58.70) 01401014.DVdala.ms
Ion 57.00 (56.70 to 57.70): 01401014.DVdala.ms
0.25 |.ig/mL 1-butanol-d10
0.25 vg/mL chlorobenzene-ds
«.t:iundance
15000 -
10000 -
5000 -
0 -
rime— > 1 1
Ion 64.00(63.701064.70): D1401014.DVdata.mt
Ion 63.00 (62 70 lo 63.70): Ol401014.DVdata.ms
Ion 50.00 (49. 70 Io50.70): Ol401014.0Vdata.ms
Ion 46 00 [45. 70 lo 46.70): D1401014.DVdalams
11.F05
A
4
51 11.78
abundance
35000 -
30000 -
25000 -
20000 -
15000 -
10000 -
5000 -
0 -
nme-.>12
Ion 11700 (116,70 to 117 70): 01401014 O^data m;
Ion 119. 00 (118.70 10 119.70): 01 401 01 4.DWatams
loo 76.00(7570 lo 76 70101401014 OVdMims
13.143
A
M
I'l
l/i
87
13.28
Abundance
15000 -
10000 -
5000 -
0 -
Time--" 10
Ion 61.00(60.70 to 61. 70): 01401014.DSdala.ms
Ion 63.00 (62 70 lo 63.70): 01401014.D\data.ms
Ion 4600 (45.70 to 46.70): 01401014 D\dataitts
11
I
157
i
77 1122
0.10 (jg/mL 1-butanol
Abundance |on 56.00 (55.70 lo 5670): 01401014.D\dala.ms
'""" lion 55.00(54.70lo5570): 01401014.D\dala.ms
: Ion 43.00(4a?0lo 43.70}. 01401014.DSdata.ms
6000 - |on 41 O0(40.70lo41.70): 01401014.D\datams
11.665
Figure 3. Extracted ion current profiles for calibration standard; concentrations as listed
38
-------
Abundance
36000 -_
34000 -^
32000 -_
30000 -
:
28000 -_
26000 -_
24000 -_
22000 -j
20000 -_
18000 -_
16000 -_
-
14000 -_
12000 -^
10000 -_
8000 ^
6000 -j
4000 -_
2000 ^
nme-> 1
0
5
1
1
T-
"o O
* i
o
1 0
•° s.
« C>J
^
4,
:J^J
^
4_
9.00
U
^
d>
i
1
2
o
£
U
iJL
1
Jui
X^
/lv^_^ ^^^ _--
1 1 AjJU^^^^
^
15.00 20.00
Figure 4. RIC, SIM mode, for unfortified drinking water from a surface water source
39
-------
Abundance
34000 -_
32000 -_
30000 -
28000 -^
26000 -_
24000 -_
22000 -_
20000 -
13000 -
16000 -
14000 -_
12000 -_
10000 -j
8000 -
6000 -_
4000 -
2000
.2
TJ
•*
o>
s
a.
CM
1 - vJ
4
A /
rime--" 10.00
15.00
20.00
Figure 5. RIQ SIM mode, for unfortified drinking water from a ground water source
40
------- |