ASTM D7598-16(2017)

Standard Test Method for Determination of Thiodiglycol in Water by Single Reaction Monitoring Liquid Chromatography/Tandem Mass Spectrometry

SIGNIFICANCE AND USE
5.1 Thiodiglycol is a Schedule 2 compound under the Chemical Weapons Convention (CWC). Schedule 2 chemicals include those that are precursors to chemical weapons, chemical weapons agents or have a number of other commercial uses. They are used as ingredients to produce insecticides, herbicides, lubricants, and some pharmaceutical products. Schedule 2 chemicals can be found in applications unrelated to chemical weapons. Thiodiglycol is both a mustard gas precursor and degradant as well as an ingredient in water-based inks, ballpoint pen inks, dyes and some pesticides.4  
5.2 This test method has been investigated for use with reagent and surface water.
SCOPE
1.1 This procedure covers the determination of thiodiglycol (TDG) in surface water by direct injection using liquid chromatography (LC) and detected with tandem mass spectrometry (MS/MS). TDG is qualitatively and quantitatively determined by this test method. This test method adheres to single reaction monitoring (SRM) mass spectrometry.  
1.2 This test method has been developed by U.S. EPA Region 5 Chicago Regional Laboratory (CRL).  
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.4 The detection verification level (DVL) and reporting range for TDG are listed in Table 1.
TABLE 1 Detection Verification Level and Reporting Range    
Analyte  
DVL (μg/L)  
Reporting Range (μg/L)  
Thiodiglycol  
20  
100–10 000  
1.4.1 The DVL is required to be at a concentration at least 3 times below the reporting limit (RL) and have a signal/noise ratio greater than 3:1. Fig. 1 displays the signal/noise ratio at the DVL.
FIG. 1 Example SRM Chromatograms Signal/Noise at Detection Verification Level  
1.4.2 The RL is the concentration of the Level 1 calibration standard as shown in Table 2. The reporting limit for this test method is 100 μg/L.  
TABLE 2 Concentrations of Calibration Standards (PPB)    
Analyte/Surrogate  
LV 1  
LV 2  
LV 3  
LV 4  
LV 5  
LV 6  
LV 7  
Thiodiglycol  
100  
250  
500  
1 000  
2 500  
5 000  
10 000  
3,3’-Thiodipropanol  
100  
250  
500  
1 000  
2 500  
5 000  
10 000  
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.  
1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

General Information

• Status: Published
• Publication Date: 14-Jun-2017
• ICS: 13.060.50 - Examination of water for chemical substances
• Technical Committee: D19 - Water
• Drafting Committee: D19.06 - Methods for Analysis for Organic Substances in Water

Relations

• Replaces: ASTM D7598-16 - Standard Test Method for Determination of Thiodiglycol in Water by Single Reaction Monitoring Liquid Chromatography/Tandem Mass Spectrometry
• Effective Date: 15-Jun-2017
• Refers: ASTM D3694-96(2024) - Standard Practices for Preparation of Sample Containers and for Preservation of Organic Constituents
• Effective Date: 01-Apr-2024
• Refers: ASTM D1129-13(2020)e2 - Standard Terminology Relating to Water
• Effective Date: 01-May-2020
• Refers: ASTM E2554-18 - Standard Practice for Estimating and Monitoring the Uncertainty of Test Results of a Test Method Using Control Chart Techniques
• Effective Date: 01-Apr-2018
• Refers: ASTM E2554-18e1 - Standard Practice for Estimating and Monitoring the Uncertainty of Test Results of a Test Method Using Control Chart Techniques
• Effective Date: 01-Apr-2018
• Refers: ASTM E2554-13 - Standard Practice for Estimating and Monitoring the Uncertainty of Test Results of a Test Method Using Control Chart Techniques
• Effective Date: 01-Apr-2013
• Refers: ASTM D2777-12 - Standard Practice for Determination of Precision and Bias of Applicable Test Methods of Committee D19 on Water
• Effective Date: 15-Jun-2012
• Refers: ASTM D3856-11 - Standard Guide for Management Systems in Laboratories Engaged in Analysis of Water
• Effective Date: 15-Nov-2011
• Refers: ASTM D3694-96(2011) - Standard Practices for Preparation of Sample Containers and for Preservation of Organic Constituents
• Effective Date: 01-May-2011
• Refers: ASTM D1129-10 - Standard Terminology Relating to Water
• Effective Date: 01-Mar-2010
• Refers: ASTM D2777-08 - Standard Practice for Determination of Precision and Bias of Applicable Test Methods of Committee D19 on Water
• Effective Date: 15-Jan-2008
• Refers: ASTM E2554-07 - Standard Practice for Estimating and Monitoring the Uncertainty of Test Results of a Test Method in a Single Laboratory Using a Control Sample Program
• Effective Date: 01-May-2007
• Refers: ASTM D1129-06a - Standard Terminology Relating to Water
• Effective Date: 01-Sep-2006
• Refers: ASTM D1129-06ae1 - Standard Terminology Relating to Water
• Effective Date: 01-Sep-2006
• Refers: ASTM D2777-06 - Standard Practice for Determination of Precision and Bias of Applicable Test Methods of Committee D19 on Water
• Effective Date: 15-Aug-2006

Overview

ASTM D7598-16(2017) is the international standard test method for the determination of thiodiglycol (TDG) in water using single reaction monitoring (SRM) liquid chromatography/tandem mass spectrometry (LC/MS/MS). Developed under the guidance of ASTM International and aligned with WTO recognized standardization principles, this method provides both qualitative and quantitative analysis of thiodiglycol in aqueous samples - specifically surface water and reagent water. Thiodiglycol is a Schedule 2 chemical under the Chemical Weapons Convention (CWC), notable as a precursor and degradation product of mustard gas, but it also has legitimate industrial uses in inks, dyes, lubricants, agrochemicals, and pharmaceuticals.

Key Topics

• Scope and Applicability:

  • Applies to the direct injection analysis of thiodiglycol in surface and reagent water.
  • Employs LC/MS/MS with single reaction monitoring (SRM).
  • Developed by the U.S. EPA Region 5 Chicago Regional Laboratory.

• Detection and Reporting Limits:

  • Detection Verification Level (DVL): 20 µg/L (micrograms per liter).
  • Reporting range: 100 to 10,000 µg/L.
  • The method requires robust calibration and quality control procedures for accuracy.

• Significance of Thiodiglycol:

  • Recognized as a chemical weapons precursor but also found in lawful industrial and consumer products such as inks and pesticides.
  • Monitoring thiodiglycol supports compliance with international treaties and ensures water safety in environmental and industrial contexts.

• Quality Control and Calibration:

  • Emphasizes stringent laboratory practices (equipment calibration, use of blanks, surrogates, and matrix spikes).
  • Data must meet criteria for recovery, precision, and absence of laboratory interference.
  • Includes recommended QC procedures to validate initial and continuing performance.

Applications

• Regulatory Compliance:
  Ensures monitoring and control of thiodiglycol in water for compliance with the Chemical Weapons Convention and national regulations. Used by environmental authorities to detect unauthorized production or release.

• Industrial Hygiene and Environmental Safety:
  Enables assessment of water contamination near production sites dealing with Schedule 2 chemicals or related manufacturing processes.

• Water Quality Monitoring:
  Applied by laboratories analyzing municipal, surface, and industrial water for thiodiglycol to identify pollution sources or validate treatment efficacy.

• Product and Process Verification:
  Used in quality assurance for manufacturers that utilize or may inadvertently generate thiodiglycol in their processes, such as ink and dye production.

• Research and Forensic Analysis:
  Essential for studying chemical degradation in environmental matrices and for forensic investigations related to chemical agent release or misuse.

Related Standards

For best practices and proper execution of ASTM D7598-16(2017), reference is made to the following standards:

• ASTM D1129: Terminology relating to water.
• ASTM D1193: Specification for reagent water.
• ASTM D2777: Practice for determination of precision and bias of applicable test methods for water.
• ASTM D3856: Guide for management systems in laboratories analyzing water.
• ASTM D3694: Preparation and preservation of sample containers for organic analysis.
• ASTM D5847: Practice for writing quality control specifications for water analysis.
• ASTM E2554: Estimating and monitoring test method uncertainty.
• U.S. EPA SW-846: Test methods for evaluating solid waste, physical/chemical methods.

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Keywords: Thiodiglycol determination, water analysis, LC/MS/MS, liquid chromatography, tandem mass spectrometry, Schedule 2 chemical, chemical weapons precursor, environmental monitoring, ASTM D7598, analytical chemistry, water quality testing.

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation:D7598 −16 (Reapproved 2017)
Standard Test Method for
Determination of Thiodiglycol in Water by Single Reaction
Monitoring Liquid Chromatography/Tandem Mass
Spectrometry
This standard is issued under the fixed designation D7598; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 2. Referenced Documents
1.1 This procedure covers the determination of thiodiglycol 2.1 ASTM Standards:
(TDG) in surface water by direct injection using liquid D1129Terminology Relating to Water
chromatography (LC) and detected with tandem mass spec- D1193Specification for Reagent Water
trometry (MS/MS). TDG is qualitatively and quantitatively D2777Practice for Determination of Precision and Bias of
determined by this test method. This test method adheres to Applicable Test Methods of Committee D19 on Water
single reaction monitoring (SRM) mass spectrometry. D3856Guide for Management Systems in Laboratories
Engaged in Analysis of Water
1.2 This test method has been developed by U.S. EPA
D3694Practices for Preparation of Sample Containers and
Region 5 Chicago Regional Laboratory (CRL).
for Preservation of Organic Constituents
1.3 The values stated in SI units are to be regarded as
D5847Practice for Writing Quality Control Specifications
standard. No other units of measurement are included in this
for Standard Test Methods for Water Analysis
standard.
E2554Practice for Estimating and Monitoring the Uncer-
tainty of Test Results of a Test Method Using Control
1.4 The detection verification level (DVL) and reporting
range for TDG are listed in Table 1. Chart Techniques
2.2 Other Documents:
1.4.1 The DVL is required to be at a concentration at least
3 times below the reporting limit (RL) and have a signal/noise U.S. EPA publication SW-846Test Methods for Evaluating
ratio greater than 3:1. Fig. 1 displays the signal/noise ratio at Solid Waste, Physical/Chemical Methods
the DVL.
3. Terminology
1.4.2 The RLis the concentration of the Level 1 calibration
standard as shown in Table 2. The reporting limit for this test 3.1 Definitions:
method is 100 µg/L.
3.1.1 For definitions of terms used in this standard, refer to
Terminology D1129.
1.5 This standard does not purport to address all of the
3.2 Definitions of Terms Specific to This Standard:
safety concerns, if any, associated with its use. It is the
3.2.1 detection verification level, DVL, n—a concentration
responsibility of the user of this standard to establish appro-
thathasasignal/noiseratiogreaterthan3:1andisatleastthree
priate safety and health practices and determine the applica-
times below the reporting limit (RL).
bility of regulatory limitations prior to use.
1.6 This international standard was developed in accor-
3.2.2 independent reference material, IRM, n—amaterialof
dance with internationally recognized principles on standard- known purity and concentration obtained either from the
ization established in the Decision on Principles for the
NationalInstituteofStandardsandTechnology(NIST)orother
Development of International Standards, Guides and Recom- reputable supplier. The IRM shall be obtained from a different
mendations issued by the World Trade Organization Technical
lot of material than is used for calibration.
Barriers to Trade (TBT) Committee.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
This test method is under the jurisdiction ofASTM Committee D19 on Water contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
andisthedirectresponsibilityofSubcommitteeD19.06onMethodsforAnalysisfor Standards volume information, refer to the standard’s Document Summary page on
Organic Substances in Water. the ASTM website.
Current edition approved June 15, 2017. Published July 2017. Originally Available from National Technical Information Service (NTIS), U.S. Depart-
approved in 2009. Last previous edition approved in 2016 as D7598 – 16. DOI: ment of Commerce, 5285 Port Royal Road, Springfield, VA, 22161 or at http://
10.1520/D7598-16R17. www.epa.gov/epawaste/hazard/testmethods/index.htm.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7598−16 (2017)
TABLE 1 Detection Verification Level and Reporting Range
include those that are precursors to chemical weapons, chemi-
Analyte DVL (µg/L) Reporting Range (µg/L) cal weapons agents or have a number of other commercial
Thiodiglycol 20 100–10 000
uses. They are used as ingredients to produce insecticides,
herbicides, lubricants, and some pharmaceutical products.
Schedule2chemicalscanbefoundinapplicationsunrelatedto
chemical weapons. Thiodiglycol is both a mustard gas precur-
3.3 Acronyms:
sor and degradant as well as an ingredient in water-based inks,
3.3.1 CCC, n—Continuing Calibration Check
ballpoint pen inks, dyes and some pesticides.
3.3.2 IC, n—Initial Calibration
5.2 This test method has been investigated for use with
3.3.3 LC, n—Liquid Chromatography
reagent and surface water.
3.3.4 LCS/LCSD, n—Laboratory Control Sample/
Laboratory Control Sample Duplicate
6. Interferences
3.3.5 MDL, n—Method Detection Limit
6.1 Methodinterferencesmaybecausedbycontaminantsin
3.3.6 MeOH, n—Methanol
solvents, reagents, glassware and other apparatus producing
–3
3.3.7 mM, n—millimolar,1×10 moles/L
discrete artifacts or elevated baselines. All of these materials
3.3.8 MRM, n—Multiple Reaction Monitoring
are demonstrated to be free from interferences by analyzing
3.3.9 MS/MSD, n—Matrix Spike/Matrix Spike Duplicate
laboratory reagent blanks under the same conditions as
samples.
3.3.10 NA, adj—Not Available
3.3.11 ND, n—non-detect
6.2 All glassware is washed in hot water with a detergent,
rinsed in hot water followed by distilled water. The glassware
3.3.12 P&A, n—Precision and Accuracy
is then dried and heated in an oven at 250°C for 15 to 30
3.3.13 PPB, n—parts per billion
minutes. All glassware is subsequently cleaned with acetone,
3.3.14 PPT, n—parts per trillion
then methanol.
3.3.15 QA, adj—Quality Assurance
6.3 All reagents and solvents should be pesticide residue
3.3.16 QC, adj—Quality Control
purity or higher to minimize interference problems.
3.3.17 RL, n—Reporting Limit
6.4 Matrix interferences may be caused by contaminants
3.3.18 RSD, n—Relative Standard Deviation
that are co-extracted from the sample. The extent of matrix
3.3.19 RT, n—Retention Time
interferences can vary considerably from sample source de-
3.3.20 SDS, n—Safety Data Sheets
pending on variations of the sample matrix.
3.3.21 SRM, n—Single Reaction Monitoring
7. Apparatus
3.3.22 SS, n—Surrogate Standard
3.3.23 TC, n—Target Compound
7.1 LC/MS/MS System:
–6
3.3.24 µM, n—micromolar,1×10 moles/L
7.1.1 LiquidChromatography(LC)System—AcompleteLC
system is needed in order to analyze samples. This should
3.3.25 VOA, n—Volatile Organic Analysis
include a sample injection system, a solvent pumping system
4. Summary of Test Methods
capable of mixing solvents, a sample compartment capable of
maintaining required temperature and a temperature controlled
4.1 This is a performance based method and modifications
columncompartment.Asystemthatiscapableofperformingat
are allowed to improve performance.
the flows, pressures, controlled temperatures, sample volumes
4.2 Forthiodiglycolanalysis,samplesareshippedtothelab
and requirements of the standard may be used.
between0°Cand6°Candanalyzedwithin7daysofcollection.
7.1.2 Analytical Column —Any column that achieves ad-
Inthe lab, the samplesarespikedwithsurrogate,filteredusing
equateresolutionmaybeused.Theretentiontimesandorderof
a syringe-driven filter unit and analyzed directly by LC/MS/
elution may change depending on the column that is used and
MS.
need to be monitored.
4.3 Thiodiglycol and 3,3’-thiodipropanol (surrogate) are
identifiedbyretentiontimeandoneSRMtransition.Thetarget
analyteandsurrogatearequantitatedusingtheSRMtransitions
Additional information about CWC and thiodiglycol is available from the
utilizing an external calibration. The final report issued for
Organization for the Prohibition of Chemical Weapons (OPCW), http://
each sample lists the concentration of TDG and the 3,3’-
www.opcw.org.
thiodipropanol surrogate recovery.
AWatersAlliance High Performance Liquid Chromatography (HPLC) System
(a trademark of the Waters Corporation, Milford, MA), or equivalent, was found
5. Significance and Use suitable for use. The multi-laboratory study included Agilent and Waters LC
systems.
5.1 Thiodiglycol is a Schedule 2 compound under the
A SIELC—A Primesep SB 5 µm, 100 Å particle, 150 mm × 2.1 mm, or
Chemical Weapons Convention (CWC). Schedule 2 chemicals equivalent, was found suitable for use.
D7598−16 (2017)
FIG. 1Example SRM Chromatograms Signal/Noise at Detection Verification Level
TABLE 2 Concentrations of Calibration Standards (PPB)
Analyte/Surrogate LV 1 LV 2 LV 3 LV 4 LV 5 LV 6 LV 7
Thiodiglycol 100 250 500 1 000 2 500 5 000 10 000
3,3’-Thiodipropanol 100 250 500 1 000 2 500 5 000 10 000
7.1.3 Tandem Mass Spectrometer (MS/MS) System—A conform to the Committee on Analytical Reagents of the
7 9
MS/MS system capable of MRM analysis. A system that is American Chemical Society. Other reagent grades may be
capableofperformingattherequirementsinthisstandardmay used provided they are first determined they are of sufficiently
be used. highpuritytopermittheirusewithoutaffectingtheaccuracyof
the measurements.
7.2 Filtration Device:
7.2.1 Hypodermic Syringe—A luer-lock tip glass syringe 8.2 Purity of Water—Unless otherwise indicated, references
capable of holding a syringe-driven filter unit. towatershallbeunderstoodtomeanreagentwaterconforming
7.2.1.1 A25-mLlocktipglasssyringesizeisrecommended toType1ofSpecificationD1193.Itmustbedemonstratedthat
since a 25-mL sample size is used in this test method. this water does not contain contaminants at concentrations
7.2.2 Filter Unit —APVDFbefilterunitswereusedtofilter sufficient to interfere with the analysis.
the samples.
8.3 Gases—Ultrapure nitrogen and argon.
8. Reagents and Materials 8.4 Acetonitrile (CAS # 75-05-8).
8.5 Methanol (CAS # 67-56-1).
8.1 Purity of Reagents—High-performance liquid chroma-
tography (HPLC) pesticide residue analysis and spectropho-
8.6 Acetone (CAS # 67-64-1).
tometry grade chemicals shall be used in all tests. Unless
8.7 Ammonium formate (CAS # 540-69-2).
indicated otherwise, it is intended that all reagents shall
8.8 Formic acid (64-18-6).
A Waters Quattro micro API mass spectrometer (a trademark of the Waters
Corporation, Milford, MA), or equivalent, was found suitable for use. The
multi-laboratory study included Applied Biosystems and Waters mass spectrom- Reagent Chemicals, American Chemical Society Specifications, American
eters. Chemical Society, Washington, DC. For Suggestions on the testing of reagents not
A Millex HV Syringe Driven Filter Unit PVDF 0.45 µm (Millipore listed by the American Chemical Society, see Annual Standards for Laboratory
Corporation, Catalog # SLHV033NS; Millex is a trademark of Merck KGAA, Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia
Darmstadt,Germany)hasbeenfoundsuitableforuseforthistestmethod,anyfilter and National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,
unit may be used that meets the performance of this test method may be used. MD.
D7598−16 (2017)
8.9 Thiodiglycol (CAS # 111-48-8). and sensitivity. Variable parameters regarding retention times,
SRMTransitions and cone and collision energies are shown in
8.10 3,3’-Thiodipropanol (CAS # 10595-09-2).
Table 4.
9. Hazards The instrument is set in the Electrospray (+) positive setting.
Capillary Voltage: 3.5 kV
9.1 Normal laboratory safety applies to this method. Ana-
Cone: Variable depending on analyte (Table 4)
Extractor: 2 Volts
lysts should wear safety glasses, gloves, and lab coats when
RF Lens: 0.2 Volts
working in the lab. Analysts should review the Safety Data
Source Temperature: 120°C
Sheets (SDS) for all reagents used in this test method.
Desolvation Temperature: 300°C
Desolvation Gas Flow: 500 L/hr
Cone Gas Flow: 25 L/hr
10. Sampling
Low Mass Resolution 1: 14.5
High Mass Resolution 1: 14.5
10.1 Sampling—Grabsamplesmustbecollectedin≥25-mL
Ion Energy 1: 0.5
pre-cleaned amber glass bottles withTeflon-lined caps demon-
Entrance Energy: –1
strated to be free of interferences. This test method requires a
Collision Energy: Variable depending on analyte (Table 4)
25-mL sample size per analysis. Conventional sampling prac- Exit Energy: 2
Low Mass Resolution 2: 15
tices should be followed. Refer to Guide D3856 and Practices
High Mass resolution 2: 15
D3694.
Ion Energy 2: 0.5
Multiplier: 650
10.2 Preservation—Store samples between 0°C and 6°C
–3
Gas Cell Pirani Gauge: 3.3 × 10 Torr
from the time of collection until analysis.Analyze the sample
Inter-Channel Delay: 0.02 seconds
Inter-Scan Delay: 0.1 seconds
within 1 day of collection.
Repeats: 1
Span: 0 Daltons
11. Preparation of LC/MS/MS
Dwell: 0.1 Seconds
11.1 LC Chromatograph Operating Conditions:
12. Calibration and Standardization
11.1.1 Injection volumes of all calibration standards and
samples are 50 µL. The first sample analyzed after the
12.1 The mass spectrometer must be calibrated per manu-
calibrationcurveisablanktoensurethereisnocarry-over.The
facturer specifications before analysis. In order that analytical
gradient conditions for the liquid chromatograph are shown in
values obtained using this test method are valid and accurate
Table 3.
within the confidence limits of the test method, the following
11.1.2 Temperatures—Column, 30°C; Sample
proceduresmustbefollowedwhenperformingthetestmethod.
compartment, 15°C.
12.2 Calibration and Standardization—To calibrate the
11.1.3 Seal Wash—Solvent: 50% Acetonitrile/50% Water;
instrument, analyze seven calibration standards containing the
Time: 5 minutes.
seven concentration levels of TDG and 3,3’-thiodipropanol
11.1.4 Needle Wash—Solvent: 50% Acetonitrile/50% Wa-
prior to analysis as shown in Table 2. A calibration stock
ter; Normal Wash, approximately 13 second wash time.
standard solution is prepared from standard materials or
11.1.5 Autosampler Purge—Three loop volumes.
purchased as certified solutions. Stock standard solution A
11.1.6 Specific instrument manufacturer wash/purge speci-
(Level 7) containing TDG and 3,3’-thiodipropanol is prepared
fications should be followed in order to eliminate sample
at Level 7 concentration and aliquots of that solution are
carry-over in the analysis of TDG.
dilutedtoprepareLevels1through6.Thefollowingstepswill
11.2 Mass Spectrometer Parameters:
produce standards with the concentration values shown in
11.2.1 In order to acquire the maximum number of data
Table 2. The analyst is responsible for recording initial
points per SRM channel while maintaining adequate
component weights carefully when working with pure materi-
sensitivity, the tune parameters may be optimized according to
als and correctly carrying the weights through the dilution
your instrument. Each peak requires at least 10 scans per peak
calculations.
for adequate quantitation. This standard contains only one
12.2.1 Prepare stock standard solution A (Level 7) by
targetcompoundandonesurrogatewhichareindifferentSRM
adding to a 100-mL volumetric flask individual methanol
experiment windows in order to optimize the number of scans
solutions of the following: 250 µL of TDG and 3,3’-
thiodipropanol each at 4 g/L, dilute to 100 mLwith water.The
preparation of the Level 7 standard can be accomplished using
TABLE 3 Gradient Conditions for Liquid Chromatography
different volumes and concentrations of stock solutions as is
Percent
accustomed in the individual laboratory. Depending on stock
500 mmolar
Time Flow Percent Percent
concentrations prepared, the solubility at that concentration
Ammonium
(min) (µL/min) CH CN Water
Formate/2%
will have to be ensured.
Formic Acid
12.2.2 Aliquots of SolutionAare then diluted with water to
0 300 0 95 5
prepare the desired calibration levels in 2-mL amber glass LC
2.5 300 0 95 5
6 300 90 5 5 vials. The calibration vials must be used within 24 hours to
10 300 90 5 5
ensure optimum results. Stock calibration standards are rou-
12 300 0 95 5
tinelyreplacedeverysixmonthsifnotpreviouslydiscardedfor
16 300 0 95 5
quality control failure. Calibration standards are not filtered.
D7598−16 (2017)
TABLE 4 Retention Times, SRM Ions, and Analyte-Specific Mass Spectrometer Parameters
SRM Mass Transition Retention Time Cone Voltage Collision Energy
Analyte
(Parent > Product) (min) (Volts) (eV)
Thiodiglycol 123.1 > 104.9 2.75 18 5
3,3’-Thiodipropanol 151.2 > 133.1 5.75 19 8
12.2.3 Inject each standard and obtain a chromatogram for calibration check standard must have a percent deviation less
each one.An external calibration is used monitoring the SRM than 30% from the calculated concentration for the target
transition of each analyte. Calibration software is utilized to analyteandsurrogate.Iftheresultsarenotwithinthesecriteria,
conduct the quantitation of the target analyte and surrogate. the problem must be corrected and either; all samples in the
TheSRMtransitionofeachanalyteisusedforquantitationand batch must be re-analyzed against a new calibration curve, or
confirmation. This gives confirmation by isolating the parent the affected results must be qualified with an indication that
ion,fragmentingittotheproduction,andalsorelatingittothe they do not fall within the performance criteria of the test
retention time in the calibration standard. method. If the analyst inspects the vial containing the end
12.2.4 Thecalibrationsoftwaremanualshouldbeconsulted calibration check standard and notices that the sample evapo-
to use the software correctly.The quantitation method is set as rated affecting the concentration, a new end calibration check
anexternalcalibrationusingthepeakareasinppborppmunits standardmaybemadeandanalyzed.Ifthisnewendcalibration
as long as the analyst is consistent. Concentrations may be checkstandardhasapercentdeviationlessthan30%fromthe
calculated using the data system software to generate linear calculatedconcentrationforthetargetanalyteandsurrogatethe
regression or quadratic calibration curves. Forcing the calibra- results may be reported unqualified.
tion through the origin is not recommended.
12.3 All samples are prepared using ClassAglass volumet-
12.2.5 Linear cali
...