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 Environmental Protection Agency 40 CFR Part 141
[EPA-HQ-OW-2023-0469; FRL-10857-04-OW]
 AGENCY: Environmental Protection Agency (EPA).
 ACTION: Request for public comment and notice of a public meeting.
 SUMMARY: The U.S. Environmental Protection Agency (EPA) is requesting public input on drinking water analytical methods for emerging contaminants in drinking water, particularly those listed on the agency's Fifth Contaminant Candidate List (CCL 5), that might support monitoring under the Unregulated Contaminant Monitoring Rule. This notice describes published drinking water analytical methods and EPA drinking water methods currently in development for the CCL and other emerging contaminants, with an expectation that some of these methods will support the sixth Unregulated Contaminant Monitoring Rule (UCMR 6) and/or other future cycles of the UCMR program. The agency is also announcing a virtual public meeting (via webinar) to discuss potential approaches to developing UCMR 6. The webinar will discuss the following: drinking water analytical methods and contaminants being considered, UCMR 6 sampling design, laboratory approval, and other potential aspects of the monitoring approach. The agenda will include time for brief remarks by participants who pre-register.
 DATES: Comments must be received on or before April 8, 2024. 
                        *Public meeting:*
                         The EPA will host a webinar regarding UCMR 6 development on April 17, 2024 and April 18, 2024. The same material will be presented twice. Please refer to the 
                        **SUPPLEMENTARY INFORMATION**
                         section for additional information on the webinar.
 ADDRESSES: The agency invites comments on analytical methods for emerging contaminants in drinking water, particularly those listed on CCL 5, to aid in the EPA's consideration of methods to support UCMR monitoring. Comments should refer to Docket ID No. EPA-HQ-OW-2023-0469 and may be submitted by any of the following options: *Federal eRulemaking Portal:**https://www.regulations.gov/​*
                         (preferred). Follow the online instructions for submitting comments.
                    *Mail:*
                         U.S. Environmental Protection Agency, EPA Docket Center, Office of Ground Water and Drinking Water Docket, Mail Code 28221T, 1200 Pennsylvania Avenue NW, Washington, DC 20460.
                    *Hand Delivery or Courier:*
                         EPA Docket Center, WJC West Building, Room 3334, 1301 Constitution Avenue NW, Washington, DC 20004. The Docket Center's hours of operations are 8:30 a.m. to 4:30 p.m., Monday through Friday (except Federal Holidays). *Instructions:*
                         All material submitted must include the Docket ID for this rulemaking. Comments received by the EPA (regardless of how they are submitted) may be posted without change to 
                        *https://www.regulations.gov/​,*
                         including any personal information provided. For detailed instructions on sending comments, see the “Public Participation” heading of the 
                        **SUPPLEMENTARY INFORMATION**
                         section of this document. Registration information for the UCMR 6 “pre-proposal” webinar can be found at 
                        *https://www.epa.gov/​dwucmr/​unregulated-contaminant-monitoring-rule-ucmr-meetings-and-materials.*
                         The webinars will begin at 11:00 a.m. eastern time and will conclude at 5:00 p.m. eastern time on the scheduled dates. Refer to the “Public Participation” heading of the 
                        **SUPPLEMENTARY INFORMATION**
                         section below for additional information if you would like to sign up to make remarks during the webinar.
 FOR FURTHER INFORMATION CONTACT: Brenda Bowden, Standards and Risk Management Division, Office of Ground Water and Drinking Water (MS 140), Environmental Protection Agency, 26 West Martin Luther King Drive, Cincinnati, OH 45268; telephone number: (513) 569-7961; or email address: 
                        *bowden.brenda@epa.gov;*
                         or Will Adams, Standards and Risk Management Division, Office of Ground Water and Drinking Water (MS 140), Environmental Protection Agency, 26 West Martin Luther King Drive, Cincinnati, OH 45268; telephone number: (513) 569-7656; or email address: 
                        *adams.william@epa.gov.*


SUPPLEMENTARY INFORMATION: Table of Contents I. Public Participation A. Written Comments on Drinking Water Analytical Methods for Emerging Contaminants B. Participation in UCMR 6 Pre-Proposal Webinar II. General Information A. Does this action apply to me? B. How does the EPA establish health standards for emerging contaminants in drinking water under the Safe Drinking Water Act? C. Why is the EPA requesting analytical method information on unregulated contaminants in drinking water? D. What is the basis for this action? III. Background A. What is the status of the drinking water analytical methods for contaminants on the CCL 5? B. What drinking water analytical methods are being developed by the EPA to address contaminants on CCL 5? 1. Draft EPA Method(s) for PFAS. 2. Draft EPA Method 562—Determination of selected pesticides in drinking water by solid phase extraction and liquid chromatography/tandem mass spectrometry (LC/MS/MS). 3. Draft EPA Method Purgeable Organics—Measurement of purgeable organic compounds in water by capillary column gas chromatography/mass spectrometry (GC/MS). This method is expected to support the analysis of drinking water for 1,2,3-trichloropropane (TCP) and other purgeable organic compounds. The target contaminants for this method are shown in Exhibit 7. 4. Draft EPA Method Legionella—Legionella spp. and Legionella pneumophila quantitative polymerase chain reaction (qPCR) detection. 5. Draft EPA Method Mycobacterium—Mycobacterium abscessus culture 
                        ( print page 8585)
                        recovery with matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS). 6. Draft EPA Method Mycobacterium qPCR- Mycobacterium avium and Mycobacterium intracellulare quantitative polymerase chain reaction (qPCR) detection. C. What other drinking water analytical methods are being considered by the EPA to address emerging contaminants? 1. Draft EPA Method EOF—Screening method for the determination of extractable organic fluorine (EOF) in drinking water by anion exchange solid phase extraction and combustion ion chromatography (CIC). 2. Draft EPA Method Microplastics—Analysis of microplastics in drinking water using spectroscopic instrumentation. D. What information should the public provide when submitting comments about drinking water analytical methods for CCL 5 and other emerging contaminants? IV. References Abbreviations and Acronyms μm Micrometer 11Cl-PF3OUdS 11-chloroeicosafluoro-3-oxaundecane-1-sulfonic Acid 4:2FTS 1H,1H, 2H, 2H-perfluorohexane Sulfonic Acid 6:2FTS 1H,1H, 2H, 2H-perfluorooctane Sulfonic Acid 8:2FTS 1H,1H, 2H, 2H-perfluorodecane Sulfonic Acid 9Cl-PF3ONS 9-chlorohexadecafluoro-3-oxanonane-1-sulfonic Acid ADONA 4,8-dioxa-3H-perfluorononanoic Acid AOF Adsorbable Organic Fluorine ASTM ASTM International BCAA Bromochloroacetic Acid BCIM Bromochloroiodomethane BDCAA Bromodichloroacetic Acid BDCNM Bromodichloronitromethane BDIM Bromodiiodomethane BFB 4-bromofluorobenzene CASRN Chemical Abstracts Service Registry Number CBI Confidential Business Information CCL Contaminant Candidate List CDIM Chlorodiiodomethane CFR Code of Federal Regulations CIC Combustion Ion Chromatography Cq Quantification Cycle CWS Community Water System DBAN Dibromoacetonitrile DBCAA Dibromochloroacetic Acid DBCNM Dibromochloronitromethane DBIM Dibromoiodomethane DBP Disinfection Byproduct DCAN Dichloroacetonitrile DCIM Dichloroiodomethane DI Deionized Water DNA Deoxyribonucleic Acid DTXSID Distributed Structure Searchable Toxicity Substance Identifiers EOF Extractable Organic Fluorine EPA U.S. Environmental Protection Agency FEM Forum on Environmental Measurement FR Federal Register FTIR Fourier Transform Infrared GC Gas Chromatography GC/MS Gas Chromatography/Mass Spectrometry HFPO-DA Hexafluoropropylene Oxide Dimer Acid ISO or ISO/TS International Organization for Standardization LC-MS/MS or LC/MS/MS Liquid Chromatography/Tandem Mass Spectrometry LDIR Laser Direct Infrared Leg16S 
                        *Legionella*
                         Species Lp16S 
                        *Legionella pneumophila* MALDI-MS Matrix-assisted Laser Desorption/Ionization Mass Spectrometry MBC Carbendazim MIP 
                        *Legionella pneumophila* mL Milliliter mm Millimeter MTBE Methyl Tert-butyl Ether NAICS North American Industry Classification System NCOD National Contaminant Occurrence Database NDBA Nitrosodibutylamine NDEA N-Nitrosodiethylamine NDMA N-Nitrosodimethylamine NDPA N-Nitrosodi-n-propylamine NDPhA N-Nitrosodiphenylamine NEtFOSAA N-ethyl Perfluorooctanesulfonamidoacetic Acid NFDHA Nonafluoro-3,6-dioxaheptanoic Acid ng/L Nanogram per Liter NMeFOSAA N-methyl Perfluorooctanesulfonamidoacetic Acid NPYR Nitrosopyrrolidine NTM Nontuberculous Mycobacteria NTNCWS Non-Transient Non-Community Water System OGWDW Office of Ground Water and Drinking Water PBI Proprietary Business Information PFAS Per- and Polyfluoroalkyl Substances PFBA Perfluorobutanoic Acid PFBS Perfluorobutanesulfonic Acid PFDA Perfluorodecanoic Acid PFDoA Perfluorododecanoic Acid PFEESA Perfluoro(2-ethoxyethane) Sulfonic Acid PFHpA Perfluoroheptanoic Acid PFHpS Perfluoroheptanesulfonic Acid PFHxA Perfluorohexanoic Acid PFHxS Perfluorohexanesulfonic Acid PFMBA Perfluoro-4-methoxybutanoic acid PFMPA Perfluoro-3-methoxypropanoic Acid PFNA Perfluorononanoic Acid PFOA Perfluorooctanoic Acid PFOS Perfluorooctanesulfonic Acid PFPeA Perfluoropentanoic Acid PFPeS Perfluoropentanesulfonic Acid PFTA Perfluorotetradecanoic Acid PFTrDA Perfluorotridecanoic Acid PFUnA Perfluoroundecanoic Acid PTFE Polytetrafluoroethylene PWS Public Water System QC Quality Control qPCR Quantitative Polymerase Chain Reaction SDWA Safe Drinking Water Act SM Standard Methods for the Examination of Water and Wastewater SPE Solid Phase Extraction SRMD Standards and Risk Management Division TBAA Tribromoacetic Acid TCEP Tris(2-chloroethyl) Phosphate TCNM Chloropicrin (trichloronitromethane) TCP Trichloropropane TIM Iodoform (triiodomethane) UCMR Unregulated Contaminant Monitoring Rule VCSB Voluntary Consensus Standards Board I. Public Participation A. Written Comments on Drinking Water Analytical Methods for Emerging Contaminants Submit your comments on drinking water analytical methods for emerging contaminants, particularly those listed in this 
                    **Federal Register**
                     notice, identified by Docket ID No. EPA-HQ-OW-2023-0469, at 
                    *https://www.regulations.gov*
                     (preferred), or using one of the other options identified in the 
                    **ADDRESSES**
                     section. Once submitted, comments cannot be edited or removed from the docket. The EPA may publish any comment received to its public docket. Do not submit any information to the EPA via 
                    *https://www.regulations.gov*
                     that you consider to be Confidential Business Information (CBI), Proprietary Business Information (PBI), or other information whose disclosure is restricted by statute. Multimedia submissions (audio, video, etc.) must be accompanied by a written comment. The written comment is considered the official comment and should include discussion of all points you want to make. The EPA will generally not consider comments or comment contents located outside of the primary submission (
                    *i.e.,*
                     on the web, cloud, or other file sharing system). Please visit 
                    *https://www.epa.gov/​dockets/​commenting-epa-dockets*
                     for additional submission methods; the full EPA public comment policy; information about CBI, PBI, or multimedia submissions; and general guidance on making effective comments. B. Participation in UCMR 6 Pre-Proposal Webinar All who want to attend the webinar, please refer to the 
                    **SUMMARY**
                     section for instructions on webinar registration. For those who want to make remarks at the webinar, the EPA is scheduling speakers. To sign up to speak, please use the online registration form available at 
                    *https://www.epa.gov/​dwucmr/​unregulated-contaminant-monitoring-rule-ucmr-meetings-and-materials*
                     or contact the EPA's support contractor, Cadmus, at 
                    *UCMRWebinar@cadmusgroup.com.*
                     The last day to pre-register to speak at the webinar is April 
                    ( print page 8586)
                    9, 2024. On April 16, (one day prior), the EPA will post an agenda that will identify scheduled speakers at: 
                    *https://www.epa.gov/​dwucmr/​unregulated-contaminant-monitoring-rule-ucmr-meetings-and-materials.*
                     If there is additional time for public speakers after scheduling those who pre-registered, EPA will take requests during the webinar via the chat box. The EPA will accommodate requests to speak (via pre-registration and during the webinar) in the order received and as time permits. The agency's current plan is to provide each speaker with ten minutes. The EPA may adjust this time depending on the number of organizations that register to speak. The agency asks that only one person present on behalf of an organization. The EPA encourages commenters to provide the agency with an advance copy of their remarks by emailing them to 
                    *UCMRWebinar@cadmusgroup.com*. The EPA may ask and answer clarifying questions during the webinar but will generally not respond to the remarks made by speakers during the webinar. Please note that any updates to the webinar plan will be posted to 
                    *https://www.epa.gov/​dwucmr/​unregulated-contaminant-monitoring-rule-ucmr-meetings-and-materials*
                     and will be emailed to those who register to participate. The EPA does not intend to publish another document in the 
                    **Federal Register**
                     announcing updates, if any. If you require the services of an interpreter or special accommodations, please identify your needs at least one week in advance as part of your registration. II. General Information A. Does this action apply to me? This notice invites comments on drinking water analytical methods and is directed to those interested in or involved with developing analytical methods for unregulated contaminants in drinking water. It may also be of particular interest to laboratories that conduct chemical or microbiological testing for drinking water contaminants, including testing in support of the UCMR program. This notice also announces a webinar to discuss potential approaches to developing UCMR 6. This notice does not impose any requirements. Category
Examples of potentially regulated entities
NAICS *State, local, & Tribal governments
State, local, and Tribal governments that analyze water samples on behalf of PWSs required to conduct such analysis; State, local, and Tribal governments that directly operate Community Water Systems (CWSs) and Non-Transient Non-Community Water Systems (NTNCWSs) required to monitor
924110Industry
Private operators of CWSs and NTNCWSs required to monitor
221310Municipalities
Municipal operators of CWSs and NTNCWSs required to monitor
924110Laboratories
Laboratories conducting analysis
541380* NAICS = North American Industry Classification System
 This table is not intended to be exhaustive, but rather provides a guide for readers regarding entities likely to be affected by this action. This table includes the types of entities that the EPA is now aware could potentially be affected by this action. Other types of entities not listed could also be affected. To determine whether your entity is affected by this action, you should carefully examine the applicability criteria found in Title 40 in the 
                    *Code of Federal Regulations*
                     (CFR) at 40 CFR 141.2 and 141.3, and the applicability criteria found in 40 CFR 141.40(a)(1) and (2). If you have questions regarding the applicability of this action to a particular entity, consult the person listed in the 
                    **FOR FURTHER INFORMATION CONTACT**
                     section. B. How does the EPA establish health standards for emerging contaminants in drinking water under the Safe Drinking Water Act? Under the 1996 amendments to the Safe Drinking Water Act (SDWA), Congress established a multi-step, risk-based approach for determining which contaminants could become subject to drinking water standards. The EPA is required to publish a Contaminant Candidate List (CCL) every five years that identifies contaminants that are not subject to any proposed or promulgated drinking water regulations, are known or anticipated to occur in Public Water Systems (PWSs), and may require future regulation under SDWA. The EPA must also determine whether or not to regulate at least five contaminants from the CCL in a separate process called Regulatory Determinations. Information on these processes can be found at: 
                    *https://www.epa.gov/​ccl.* Per SDWA, the EPA implements section 1445(a)(2), Monitoring Program for Unregulated Contaminants. The EPA requires that PWSs monitor for a new set of unregulated contaminants every five years to generate occurrence data in support of the agency's CCL and Regulatory Determination processes. The EPA must vary the frequency and schedule for monitoring based on the number of people served, the source water, and the contaminants likely to be found. The data collected through the UCMR program are made available to the public through the National Contaminant Occurrence Database (NCOD) for drinking water. UCMR results can be viewed by the public via NCOD (
                    *https://www.epa.gov/​sdwa/​national-contaminant-occurrence-database-ncod*) or via the UCMR web page at: 
                    *https://www.epa.gov/​dwucmr.* C. Why is the EPA requesting analytical method information on unregulated contaminants in drinking water? Analytical methods are essential to gathering occurrence data under the UCMR program. Robust analytical methods with sufficient sensitivity, accuracy, and precision are needed. D. What is the basis for this action? This notice provides the public with the EPA's assessment of published drinking water analytical methods and methods in development for emerging contaminants, particularly those focusing on the CCL 5. The EPA is seeking public comments on method development to reach a broader audience and provide an opportunity to improve public participation. Separate public meetings on method development have not been well attended in the past, and this 
                    **Federal Register**
                     notice enables those who cannot participate in the meeting to provide input. This notice also announces webinars in April 2024 that will allow for early engagement in the agency's development of UCMR 6.
                    ( print page 8587) III. Background A. What is the status of the drinking water analytical methods for contaminants on the CCL 5? Exhibits 1-5 list the contaminants on the final CCL 5 in the 
                    **Federal Register**
                     published November 14, 2022 (87 FR 68060) (USEPA, 2022b). The current status of drinking water analytical methods from the EPA and voluntary consensus standards bodies (VCSBs) such as, ASTM International (ASTM), Standard Methods (SM), and International Organization for Standardization (ISO), are included in this notice. The ASTM, SM, and ISO methods listed in Exhibits 1-5 may or may not contain the standards and quality control (QC) requirements deemed necessary by the agency and may need to be adapted to support UCMR monitoring. Exhibits 6-10 list methods in development by the EPA for contaminants from CCL 5 that do not currently have drinking water analytical methods. The EPA recognizes that there may be other entities developing drinking water analytical methods and encourages commenters to make the agency aware of them. Please submit comments to the EPA following the process described in section III.D of this notice. Exhibit 1—CCL 5 Chemical Contaminants/Groups and Associated Drinking Water Analytical Methods
Chemical name
CASRN 1
DTXSID 2
Drinking water method(s) 31,2,3-Trichloropropane
96-18-4
DTXSID9021390
In Development, EPA 502.2, EPA 504.1, EPA 524.2, EPA 524.3, EPA 524.4, EPA 551.1, ASTM D5790-18, SM 6200 B, SM 6200 C.1,4-Dioxane
123-91-1
DTXSID4020533
EPA 522, EPA 541.17-alpha ethynyl estradiol
57-63-6
DTXSID5020576
EPA 539.2,4-Dinitrophenol
51-28-5
DTXSID0020523
EPA 528.2-Aminotoluene
95-53-4
DTXSID1026164
EPA 530.2-Hydroxyatrazine
2163-68-0
DTXSID6037807
Research Needed.6-Chloro-1,3,5-triazine-2,4-diamine
3397-62-4
DTXSID1037806
Research Needed.Acephate
30560-19-1
DTXSID8023846
EPA 538.Acrolein
107-02-8
DTXSID5020023
Research Needed.alpha-Hexachlorocyclohexane
319-84-6
DTXSID2020684
EPA 508, EPA 508.1, EPA 525.2, EPA 525.3.Anthraquinone
84-65-1
DTXSID3020095
Research Needed.Bensulide
741-58-2
DTXSID9032329
EPA 540, EPA 543.Bisphenol A
80-05-7
DTXSID7020182
SM 6810 B.Boron
7440-42-8
DTXSID3023922
EPA 200.5, EPA 200.7, SM 3120 B, SM 4500-B B, SM 4500-B C.Bromoxynil
1689-84-5
DTXSID3022162
In Development.Carbaryl
63-25-2
DTXSID9020247
EPA 531.1, EPA 531.2, ASTM D5315-04, SM 6610 B.Carbendazim (MBC)
10605-21-7
DTXSID4024729
In Development.Chlordecone (Kepone)
143-50-0
DTXSID1020770
EPA 527 *, In Development.Chlorpyrifos
2921-88-2
DTXSID4020458
EPA 525.2, EPA 525.3, EPA 527, EPA 600/R-16/114.Cobalt
7440-48-4
DTXSID1031040
EPA 200.7, EPA 200.8, EPA 200.9, ASTM D3558-15 A, ASTM D3558-15 B, SM 3111 B, SM 3111 C, SM 3113 B, SM 3120 B.Cyanotoxins 4
                             5
Multiple
Multiple
See Exhibit 2.Desethylatrazine
6190-65-4
DTXSID5037494
EPA 523, EPA 536.Desisopropyl atrazine
1007-28-9
DTXSID0037495
EPA 523, EPA 536.Desvenlafaxine
93413-62-8
DTXSID40869118
Research Needed.Diazinon
333-41-5
DTXSID9020407
EPA 526.Dicrotophos
141-66-2
DTXSID9023914
EPA 538, EPA 600/R-16/114.Dieldrin
60-57-1
DTXSID9020453
EPA 505, EPA 508, EPA 508.1, EPA 525.2, EPA 525.3, ASTM D5175-91.Dimethoate
60-51-5
DTXSID7020479
EPA 527.Disinfection byproducts (DBPs) 4
                             6
Multiple
Multiple
See Exhibit 3.Diuron
330-54-1
DTXSID0020446
EPA 532.Ethalfluralin
55283-68-6
DTXSID8032386
Research Needed.Ethoprop
13194-48-4
DTXSID4032611
EPA 507, EPA 525.2, EPA 525.3.Fipronil
120068-37-3
DTXSID4034609
In Development.Fluconazole.
86386-73-4
DTXSID3020627
Research Needed.Flufenacet
142459-58-3
DTXSID2032552
In Development.Fluometuron
2164-17-2
DTXSID8020628
EPA 532.Iprodione
36734-19-7
DTXSID3024154
In Development.Lithium
7439-93-2
DTXSID5036761
EPA 200.7, ASTM D1976-20, SM 3111 B, SM 3120 B, SM 3500-Li B.Malathion
121-75-5
DTXSID4020791
EPA 527.Manganese
7439-96-5
DTXSID2024169
EPA 200.5, EPA 200.7, EPA 200.8, EPA 200.9, SM 3111 B, SM 3111 C, SM 3113 B, SM 3120 B, SM 3500-Mn B.Methomyl
16752-77-5
DTXSID1022267
EPA 531.1, EPA 531.2, EPA 540, ASTM D5315-04, ASTM D7645-23, SM 6610 B.Methyl tert-butyl ether (MTBE)
1634-04-4
DTXSID3020833
EPA 524.2, EPA 524.3, EPA 524.4, ASTM D5790-18, SM 6200 B, SM 6200 C.Methylmercury
22967-92-6
DTXSID9024198
Research Needed.Molybdenum
7439-98-7
DTXSID1024207
EPA 200.7, EPA 200.8, SM 3111 D, SM 3113 B, SM 3120 B.Nonylphenol 7
25154-52-3
DTXSID3021857
EPA 559.Norflurazon
27314-13-2
DTXSID8024234
EPA 507, EPA 525.2, EPA 525.3, EPA 527.*Oxyfluorfen
42874-03-3
DTXSID7024241
EPA 525.3.( print page 8588)Per- and polyfluoroalkyl substances (PFAS) 4
                             8
Multiple
Multiple
See Exhibit 4.Permethrin
52645-53-1
DTXSID8022292
EPA 508, EPA 508.1, EPA 525.2, EPA 525.3.Phorate
298-02-2
DTXSID4032459
EPA 525.3, EPA 600/R-16/114.Phosmet
732-11-6
DTXSID5024261
Research Needed.Phostebupirim
96182-53-5
DTXSID1032482
Research Needed.Profenofos
41198-08-7
DTXSID3032464
EPA 525.3.Propachlor
1918-16-7
DTXSID4024274
EPA 508, EPA 508.1, EPA 525.2, EPA 525.3.Propanil
709-98-8
DTXSID8022111
EPA 532.Propargite
2312-35-8
DTXSID4024276
Research Needed.Propazine
139-40-2
DTXSID3021196
EPA 507, EPA 523, EPA 525.2, EPA 525.3, EPA 527, EPA 536.Propoxur
114-26-1
DTXSID7021948
EPA 531.1, EPA 531.2, ASTM D5315-04, SM 6610 B.Quinoline
91-22-5
DTXSID1021798
EPA 530, EPA 538.Tebuconazole
107534-96-3
DTXSID9032113
EPA 525.3, EPA 540, EPA 543.Terbufos
13071-79-9
DTXSID2022254
EPA 526.Thiamethoxam
153719-23-4
DTXSID2034962
In Development.Tri-allate
2303-17-5
DTXSID5024344
Research Needed.Tribufos
78-48-8
DTXSID1024174
EPA 525.3.Tributyl phosphate
126-73-8
DTXSID3021986
Research Needed.Trimethylbenzene (1,2,4-)
95-63-6
DTXSID6021402
EPA 502.2, EPA 524.2, EPA 524.3, EPA 524.4, ASTM D5790-18, SM 6200 B, SM 6200 C.Tris(2-chloroethyl) phosphate (TCEP)
115-96-8
DTXSID5021411
Research Needed.Tungsten
7440-33-7
DTXSID8052481
Research Needed.Vanadium
7440-62-2
DTXSID2040282
EPA 200.5, EPA 200.7, EPA 200.8, SM 3111 D, SM 3120 B, SM 3500-V B.1
                         Chemical Abstracts Service Registry Number (CASRN) is a unique identifier assigned by the Chemical Abstracts Service (a division of the American Chemical Society) to every chemical substance (organic and inorganic compounds, polymers, elements, nuclear particles, etc.) in the open scientific literature. It contains up to 10 digits, separated by hyphens into three parts.2
                         Distributed Structure Searchable Toxicity Substance Identifiers (DTXSID) is a unique substance identifier used in EPA's CompTox Chemicals database, where a substance can be any single chemical, mixture, or polymer.3
                         Published methods are listed by EPA number or VCSB number. Methods in development by the EPA, or for which research is still needed, are also identified.4
                         EPA's approach to listing cyanotoxins, DBPs, and PFAS as groups on CCL 5 as opposed to listing them as individual contaminants limits duplication of agency efforts, such as data gathering, analyses and evaluations. Listing these three chemical groups on the CCL 5 does not necessarily mean that EPA will make subsequent regulatory decisions for the entire group.5
                         As defined in CCL 5, toxins naturally produced and released by some species of cyanobacteria (also known as “blue-green algae”). The group of cyanotoxins includes, but is not limited to: anatoxin-a, cylindrospermopsin, microcystins, and saxitoxin as shown in Exhibit 2.6
                         This CCL 5 group includes 23 unregulated DBPs as shown in Exhibit 3.7
                         The CCL 5 lists a general nonylphenol with a CASRN of 25154-52-3. EPA Method 559 analyzes nonylphenol with a CASRN of 84852-15-3 and reports technical nonylphenol, comprised mostly of branched C9-alkyl phenols, and not linear nonylphenol (CASRN 104-40-5) which is a laboratory generated chemical not typically found in the environment.8
                         The CCL 5 structural definition of per- and polyfluoroalkyl substances (PFAS) includes chemicals that contain at least one of these three structures as shown in Exhibit 4 (except for PFOA and PFOS which are already in the regulatory process):1. R-(CF2)-CF(R′)R′′, where both the CF2 and CF moieties are saturated carbons, and none of the R groups can be hydrogen.2. R-CF2OCF2-R′, where both the CF2 moieties are saturated carbons, and none of the R groups can be hydrogen.3. CF3C(CF3)RR′, where all the carbons are saturated, and none of the R groups can be hydrogen.* EPA Method 527 indicates these specific contaminants may have potential complications.
 The CCL 5 includes cyanotoxins as a group, including but not limited to the contaminants in Exhibit 2. The EPA recognizes there are other contaminants in this group such as, nodularin-R (which is not a microcystin), as well as, derivatives and congeners of anatoxin-a, cylindrospermopsin, and saxitoxin (
                    *e.g.,*
                     homoanatoxin-a, deoxy-cylindrospermopsin, and other paralytic shellfish poisons). Exhibit 2—Unregulated Cyanotoxins Group on CCL 5 and Associated Drinking Water Analytical Methods
[See Exhibit 1 footnote 4]
Chemical name
CASRN 1
DTXSID 2
Drinking water method(s) 3Anatoxin-a
64285-06-9
DTXSID50867064
EPA 545.Cylindrospermopsin
143545-90-8
DTXSID2031083
EPA 545.Saxitoxin
35523-89-8
DTXSID3074313
Research Needed.**Microcystins**Microcystin LA
96180-79-9
DTXSID3031656
EPA 544.Microcystin LR
101043-37-2
DTXSID3031654
EPA 544.Microcystin LW
157622-02-1
DTXSID70891285
Research Needed.Microcystin RR
111755-37-4
DTXSID40880085
EPA 544.( print page 8589)Microcystin YR
101064-48-6
DTXSID00880086
EPA 544.1
                         Chemical Abstracts Service Registry Number (CASRN) is a unique identifier assigned by the Chemical Abstracts Service (a division of the American Chemical Society) to every chemical substance (organic and inorganic compounds, polymers, elements, nuclear particles, etc.) in the open scientific literature. It contains up to 10 digits, separated by hyphens into three parts.2
                         Distributed Structure Searchable Toxicity Substance Identifiers (DTXSID) is a unique substance identifier used in EPA's CompTox Chemicals database, where a substance can be any single chemical, mixture, or polymer.3
                         Published methods are listed by EPA number or VCSB number. Methods in development by the EPA, or for which research is still needed, are also identified.
 Exhibit 3—Unregulated DBP Group on CCL 5 and Associated Drinking Water Analytical Methods
[See Exhibit 1 footnote 5]
Chemical name
CASRN 1
DTXSID 2
Drinking water method(s) 3**Haloacetic Acids**Bromochloroacetic acid (BCAA)
5589-96-8
DTXSID4024642
EPA 552.1, EPA 552.2, EPA 552.3, EPA 557, SM 6251 B.Bromodichloroacetic acid (BDCAA)
71133-14-7
DTXSID4024644
EPA 552.2, EPA 552.3, EPA 557.Dibromochloroacetic acid (DBCAA)
5278-95-5
DTXSID3031151
EPA 552.2, EPA 552.3, EPA 557.Tribromoacetic acid (TBAA)
75-96-7
DTXSID6021668
EPA 552.2, EPA 552.3, EPA 557.**Haloacetonitriles**Dichloroacetonitrile (DCAN)
3018-12-0
DTXSID3021562
EPA 551.1.Dibromoacetonitrile (DBAN)
3252-43-5
DTXSID3024940
EPA 551.1.**Halonitromethanes**Bromodichloronitromethane (BDCNM)
918-01-4
DTXSID4021509
Research Needed.Chloropicrin (trichloronitromethane, TCNM)
76-06-2
DTXSID0020315
EPA 551.1.Dibromochloronitromethane (DBCNM)
1184-89-0
DTXSID00152114
Research Needed.**Iodinated Trihalomethanes**Bromochloroiodomethane (BCIM)
34970-00-8
DTXSID9021502
Research Needed.Bromodiiodomethane (BDIM)
557-95-9
DTXSID70204235
Research Needed.Chlorodiiodomethane (CDIM)
638-73-3
DTXSID20213251
Research Needed.Dibromoiodomethane (DBIM)
593-94-2
DTXSID60208040
Research Needed.Dichloroiodomethane (DCIM)
594-04-7
DTXSID7021570
Research Needed.Iodoform (triiodomethane, TIM)
75-47-8
DTXSID4020743
Research Needed.**Nitrosamines**Nitrosodibutylamine (NDBA)
924-16-3
DTXSID2021026
EPA 521, SM 6450 B, SM 6450 C.N-Nitrosodiethylamine (NDEA)
55-18-5
DTXSID2021028
EPA 521, SM 6450 B, SM 6450 C.N-Nitrosodimethylamine (NDMA)
62-75-9
DTXSID7021029
EPA 521, SM 6450 B, SM 6450 C.N-Nitrosodi-n-propylamine (NDPA)
621-64-7
DTXSID6021032
EPA 521, SM 6450 B, SM 6450 C.N-Nitrosodiphenylamine (NDPhA)
86-30-6
DTXSID6021030
Research Needed.Nitrosopyrrolidine (NPYR)
930-55-2
DTXSID8021062
EPA 521, SM 6450 B, SM 6450 C.**Others**Chlorate
14866-68-3
DTXSID3073137
EPA 300.1, ASTM D6581-18, SM 4110 D.Formaldehyde
50-00-0
DTXSID7020637
EPA 554, EPA 556.1, SM 6252 B.*1
                         Chemical Abstracts Service Registry Number (CASRN) is a unique identifier assigned by the Chemical Abstracts Service (a division of the American Chemical Society) to every chemical substance (organic and inorganic compounds, polymers, elements, nuclear particles, etc.) in the open scientific literature. It contains up to 10 digits, separated by hyphens into three parts.2
                         Distributed Structure Searchable Toxicity Substance Identifiers (DTXSID) is a unique substance identifier used in EPA's CompTox Chemicals database, where a substance can be any single chemical, mixture, or polymer.3
                         Published methods are listed by EPA number or VCSB number. Methods in development by the EPA, or for which research is still needed, are also identified.* SM 6252 B is in the 24th edition of SM titled as proposed.
 The CCL 5 included PFAS as a group which includes thousands of PFAS chemicals per the CCL 5 structural definition (USEPA, 2022b). Exhibit 4 lists the PFAS that EPA has available drinking water analytical methods. The 
                    ( print page 8590)
                    EPA recognizes that the PFAS in Exhibit 4 only captures a subset of the thousands of PFAS compounds encompassed in the CCL 5 structural definition (USEPA, 2023). Exhibit 4—Unregulated PFAS Group With Available Drinking Water Analytical Methods
[See Exhibit 1 footnote 7]
Chemical name 1
CASRN 2
DTXSID 3
Drinking water
                             
                                method(s) 411-chloroeicosafluoro-3-oxaundecane-1-sulfonic acid (11Cl-PF3OUdS)
763051-92-9
DTXSID40892507
EPA 533, EPA 537.1.9-chlorohexadecafluoro-3-oxanonane-1-sulfonic acid (9Cl-PF3ONS)
756426-58-1
DTXSID80892506
EPA 533, EPA 537.1.4,8-dioxa-3H-perfluorononanoic acid (ADONA)
919005-14-4
DTXSID40881350
EPA 533, EPA 537.1.Hexafluoropropylene oxide dimer acid (HFPO-DA)
13252-13-6
DTXSID70880215
EPA 533, EPA 537.1.Nonafluoro-3,6-dioxaheptanoic acid (NFDHA)
151772-58-6
DTXSID30382063
EPA 533.Perfluorobutanoic acid (PFBA)
375-22-4
DTXSID4059916
EPA 533.Perfluorobutanesulfonic acid (PFBS)
375-73-5
DTXSID5030030
EPA 533, EPA 537.1.1H,1H, 2H, 2H-perfluorodecane sulfonic acid (8:2FTS)
39108-34-4
DTXSID00192353
EPA 533.Perfluorodecanoic acid (PFDA)
335-76-2
DTXSID3031860
EPA 533, EPA 537.1.Perfluorododecanoic acid (PFDoA)
307-55-1
DTXSID8031861
EPA 533, EPA 537.1.Perfluoro(2-ethoxyethane)sulfonic acid (PFEESA)
113507-82-7
DTXSID50379814
EPA 533.Perfluoroheptanesulfonic acid (PFHpS)
375-92-8
DTXSID8059920
EPA 533.Perfluoroheptanoic acid (PFHpA)
375-85-9
DTXSID1037303
EPA 533, EPA 537.1.1H,1H, 2H, 2H-perfluorohexane sulfonic acid (4:2FTS)
757124-72-4
DTXSID30891564
EPA 533.Perfluorohexanesulfonic acid (PFHxS)
355-46-4
DTXSID7040150
EPA 533, EPA 537.1.Perfluorohexanoic acid (PFHxA)
307-24-4
DTXSID3031862
EPA 533, EPA 537.1.Perfluoro-3-methoxypropanoic acid (PFMPA)
377-73-1
DTXSID70191136
EPA 533.Perfluoro-4-methoxybutanoic acid (PFMBA)
863090-89-5
DTXSID60500450
EPA 533.Perfluorononanoic acid (PFNA)
375-95-1
DTXSID8031863
EPA 533, EPA 537.1.1H,1H, 2H, 2H-perfluorooctane sulfonic acid (6:2FTS)
27619-97-2
DTXSID6067331
EPA 533.Perfluorooctanesulfonic acid (PFOS)
1763-23-1
DTXSID3031864
EPA 533, EPA 537.1.Perfluorooctanoic acid (PFOA)
335-67-1
DTXSID8031865
EPA 533, EPA 537.1.Perfluoropentanoic acid (PFPeA)
2706-90-3
DTXSID6062599
EPA 533.Perfluoropentanesulfonic acid (PFPeS)
2706-91-4
DTXSID8062600
EPA 533.Perfluoroundecanoic acid (PFUnA)
2058-94-8
DTXSID8047553
EPA 533, EPA 537.1.N-ethyl perfluorooctanesulfonamidoacetic acid (NEtFOSAA)
2991-50-6
DTXSID5062760
EPA 537.1.N-methyl perfluorooctanesulfonamidoacetic acid (NMeFOSAA)
2355-31-9
DTXSID10624392
EPA 537.1.Perfluorotetradecanoic acid (PFTA)
376-06-7
DTXSID3059921
EPA 537.1.Perfluorotridecanoic acid (PFTrDA)
72629-94-8
DTXSID90868151
EPA 537.1.1
                         The CCL 5 structural definition of per- and polyfluoroalkyl substances (PFAS) includes chemicals that contain at least one of these three structures as shown in Exhibit 4 (except for PFOA and PFOS which are already in the regulatory process):1. R-(CF2)-CF(R′)R′′, where both the CF2 and CF moieties are saturated carbons, and none of the R groups can be hydrogen.2. R-CF2OCF2-R′, where both the CF2 moieties are saturated carbons, and none of the R groups can be hydrogen.3. CF3C(CF3)RR′, where all the carbons are saturated, and none of the R groups can be hydrogen.2
                         Chemical Abstracts Service Registry Number (CASRN) is a unique identifier assigned by the Chemical Abstracts Service (a division of the American Chemical Society) to every chemical substance (organic and inorganic compounds, polymers, elements, nuclear particles, etc.) in the open scientific literature. It contains up to 10 digits, separated by hyphens into three parts.3
                         Distributed Structure Searchable Toxicity Substance Identifiers (DTXSID) is a unique substance identifier used in EPA's CompTox Chemicals database, where a substance can be any single chemical, mixture, or polymer.4
                         Published methods are listed by EPA number or VCSB number. Methods in development by the EPA, or for which research is still needed, are also identified.
 Exhibit 5—Unregulated Microbial Contaminants on CCL 5 and Associated Drinking Water Analytical Methods
Microorganism
Type of microorganism
Drinking water method(s) 1Adenovirus
Virus
Research Needed.Caliciviruses
Virus
Research Needed.*Campylobacter jejuni*
Bacteria
Research Needed.*Escherichia coli (O157)*
Bacteria
Research Needed.Enterovirus
Virus
EPA 1615.*Helicobacter pylori*
Bacteria
Research Needed.*Legionella pneumophila*
Bacteria
In Development, ASTM D8429-21 *, ISO 11731:2017, ISO/TS 12869:2019.*Mycobacterium abscessus*
Bacteria
In Development.*Mycobacterium avium*
Bacteria
In Development.*Naegleria fowleri*
Protozoa
SM 9750.***Pseudomonas aeruginosa*
Bacteria
ASTM D5246-19, SM 9213 E, SM 9213 F, SM 9213 G.*Shigella sonnei*
Bacteria
Research Needed.1
                         Published methods are listed by EPA number or VCSB number. Methods in development by the EPA, or for which research is still needed, are also identified.* Commonly known as Legiolert® test.** SM 9750 is in the 24th edition of SM titled as proposed.
 
 
 B. What drinking water analytical methods are being developed by the EPA to address contaminants on CCL 5? 1. Draft EPA Method(s) for PFAS. The agency continues to conduct research and monitor advances and techniques that may improve our ability to measure PFAS. Preliminary studies have been performed looking at potential method development for PFAS contaminants that are not analyzed in EPA Methods 533 or 537.1. The EPA Methods 533 and 537.1 both address a wide variety of PFAS. These methods were developed focusing on the largest array of PFAS that were commercially available at the time (as certified reference standards) and that could be analyzed while routinely meeting all method-specified quality control criteria (towards the goal of generating accurate and precise results in drinking water sample matrices). EPA is working to expand the method target analyte scope and is soliciting comment and supporting performance data from stakeholders that have conducted similar studies (
                    *e.g.,*
                     incorporating PFAS with carbon chains less than or equal to three carbons and/or improvements in analytical processing times, such as employing direct injection techniques that could simplify or eliminate the solid-phase extraction step (USEPA, 2019b). EPA anticipates that such improvements would enhance laboratory capability and capacity. EPA invites comments on analytical improvements to Methods 533 and 537.1 or alternative techniques that could prove to be effective at measuring PFAS in drinking water. 2. Draft EPA Method 562—Determination of selected pesticides in drinking water by solid phase extraction and liquid chromatography/tandem mass spectrometry (LC/MS/MS). The target contaminants for this method consist of the seven pesticides and three degradates shown in Exhibit 6. Exhibit 6—Target Contaminants in Draft EPA Method 562
Chemical name
CASRN 1
DTXSID 2Bromoxynil
1689-84-5
DTXSID3022162.Carbendazim (MBC)
10605-21-7
DTXSID4024729Chlordecone (Kepone)
143-50-0
DTXSID1020770Clothianidin
210880-92-5
DTXSID2034465Fipronil
120068-37-3
DTXSID4034609Fipronil sulfide
120067-83-6
DTXSID50869644Fipronil sulfone
120068-36-2
DTXSID6074750Flufenacet
142459-58-3
DTXSID2032552Iprodione
36734-19-7
DTXSID3024154Thiamethoxam
153719-23-4
DTXSID20349621
                         Chemical Abstracts Service Registry Number (CASRN) is a unique identifier assigned by the Chemical Abstracts Service (a division of the American Chemical Society) to every chemical substance (organic and inorganic compounds, polymers, elements, nuclear particles, etc.) in the open scientific literature. It contains up to 10 digits, separated by hyphens into three parts.2
                         Distributed Structure Searchable Toxicity Substance Identifiers (DTXSID) is a unique substance identifier used in EPA's CompTox Chemicals database, where a substance can be any single chemical, mixture, or polymer.
 The aqueous samples are preserved with ascorbic acid to mitigate free chlorine disinfection and sodium bisulfate to inhibit microbial growth. Extraction efficiency is monitored by adding surrogate compounds to the aqueous samples prior to extraction. Chlordecone and iprodione are known to degrade in the presence of methanol (Bichon et al., 2015; Anisuzzaman et al., 2008); therefore, efforts to avoid the use of methanol were prioritized. Preliminary holding time studies support an aqueous holding time of 14 days and an extract holding time of 28 days. Solid phase extraction (SPE) using divinylbenzene sorbent is used to concentrate the contaminants from the aqueous sample. Additional research may be performed which may allow use of other SPE sorbents provided performance requirements are met. The samples are fully loaded onto the SPE cartridge, followed by a deionized (DI) water bottle wash then an acetone bottle wash to elute the target contaminants. Following elution, nitrogen evaporation is used to reduce the extract. The extract is brought to final volume with an acetone and acetonitrile mixture. The target contaminants are separated using reversed phase liquid chromatography and detected using LC/MS/MS using both positive and negative electrospray ionization. Selected reaction monitoring is used to detect a product ion to maximize selectivity. Instrument variability is corrected using an internal standard. The EPA invites comments to support development of this pesticide method. The agency is particularly interested in comments about additional SPE sorbents that provide contaminant recovery meeting the drinking water program's data quality objectives. 3. Draft EPA Method Purgeable Organics—Measurement of purgeable organic compounds in water by capillary column gas chromatography/mass spectrometry (GC/MS). This method is expected to support the analysis of drinking water for 1,2,3-trichloropropane (TCP) and other purgeable organic compounds. The target contaminants for this method are shown in Exhibit 7. Exhibit 7—Target Contaminants in Draft EPA Method Purgeable Organics
Chemical name
CASRN 1
DTXSID 21,2-dibromo-3-chloropropane
96-12-8
DTXSID30204131,2-dibromoethane
106-93-4
DTXSID30204151,2,3-trichloropropane
96-18-4
DTXSID90213901,2,4-trimethylbenzene
95-63-6
DTXSID6021402( print page 8592)Methyl-tert-butyl Ether
1634-04-4
DTXSID30208331
                         Chemical Abstracts Service Registry Number (CASRN) is a unique identifier assigned by the Chemical Abstracts Service (a division of the American Chemical Society) to every chemical substance (organic and inorganic compounds, polymers, elements, nuclear particles, etc.) in the open scientific literature. It contains up to 10 digits, separated by hyphens into three parts.2
                         Distributed Structure Searchable Toxicity Substance Identifiers (DTXSID) is a unique substance identifier used in EPA's CompTox Chemicals database, where a substance can be any single chemical, mixture, or polymer.
 EPA Methods 524.2, 524.3, and 524.4 are used to analyze a variety of organic compounds; however, this method in development is targeting the selected contaminants in Exhibit 9 at quantifiable levels lower than the EPA Methods 524.3 and 524.4 currently achieve (USEPA, 1995g; USEPA, 2009a; USEPA, 2013a). In the draft method, headspace-free samples are collected in amber glass vials with polytetrafluoroethylene (PTFE)-faced septa. Samples are dechlorinated with ascorbic acid and the pH is adjusted with maleic acid. A 5.0 milliliter (mL) or 25-mL aliquot of the sample is transferred to a glass sparging vessel along with appropriate amounts of internal standard and QC compounds. The method contaminants are purged from the water using helium or nitrogen and trapped on a sorbent material. The sample is then heated and backflushed with gas chromatography (GC) carrier gas to transfer the contaminants directly into the gas chromatographic inlet. The inlet is operated in the split mode to achieve the desired desorb flow rates and further reduce water transmission. Contaminants are transferred onto a capillary GC column, which is temperature programmed to optimize the separation of method contaminants. Compounds eluting from the GC are directed into a mass spectrometer for detection and quantitation. The method contaminants are identified by comparing the acquired mass spectra and retention times to reference spectra and retention times. The concentration of each contaminant is calculated using the internal standard technique and response curves obtained via procedural calibration. The draft method may differ from EPA Methods 524.2, 524.3, and 524.4 due to removing the requirement for a 4-bromofluorobenzene (BFB) tune as part of the GC/MS optimization and initial calibration, and instead optimizing tuning to maximum ion transmission for the target contaminants of interest. EPA Methods 524.2, 524.3, and 524.4 require a BFB tune, and the draft method will allow optimizing tuning to maximum ion transmission for the target analytes in Exhibit 7. By optimizing conditions specifically for the target contaminants of interest, lower quantitation limits may be achieved. Other changes, such as adjusting the GC split ratio would also be optimized to focus on the specific set of contaminants listed in Exhibit 7. The EPA invites comments to support development of this method. The agency is particularly interested in techniques to quantify 1,2,3-TCP at low levels (~5 nanograms per liter (ng/L)). 4. Draft EPA Method 
                    *Legionella*
                    —
                    *Legionella spp.*
                     and 
                    *Legionella pneumophila*
                     quantitative polymerase chain reaction (qPCR) detection. The target contaminants for this method are shown in Exhibit 8. Exhibit 8—Target Contaminants in Draft EPA Method Legionella
Microorganism
Type of microorganism*Legionella*
                             species (Leg16S)
Bacteria.*Legionella pneumophila*
                             (MIP)
Bacteria.*Legionella pneumophila*
                             (Lp16S)
Bacteria.
 For this method in development, one assay under consideration will detect all 
                    *Legionella*
                     species (there are ~53 recognized species). There are two other assays under consideration for 
                    *Legionella pneumophila*
                     detection. For this method, a one-liter sample is collected in a high-density polypropylene bottle containing sodium thiosulfate for dechlorination. The sample is vacuumed filtered through a 0.45 micrometer (μm) polycarbonate membrane. The captured microbial deoxyribonucleic acid (DNA) is extracted from the membrane. The extracted DNA is analyzed using three qPCR assays utilizing a qPCR instrument. This method will detect and quantify the targeted microbe of interest. The method identifies the target bacteria using primer-probe specific to the microbe of interest, and the resulting qPCR gene product (DNA sequence) molecular weight is checked. The instrument will generate an amplification curve if the targeted bacteria is present in a sample. As the curve passes the 0.4 threshold, a quantification cycle (Cq) value is determined. The targeted bacteria DNA (Cq value) is then quantified using a standard curve generated from genomic DNA. The method contains other QC samples, including, positive controls such as, the standard curve and negative controls, such as, internal controls, method blanks, extraction blanks, and non-template controls. The EPA invites comments to support the development of a 
                    *Legionella spp.*
                     and 
                    *Legionella pneumophila*
                     method. The agency is specifically interested in information on environmental laboratory capabilities to perform this method. 5. Draft EPA Method 
                    *Mycobacterium—Mycobacterium abscessus*
                     culture recovery with matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS). The target contaminants for this method are shown in Exhibit 9.
                    ( print page 8593) Exhibit 9—Target Contaminants in Draft EPA Method Mycobacterium
Microorganism
Type of microorganism*Mycobacterium abscessus*
Bacteria.*Mycobacterium mucogenicum*
                             (potentially)
Bacteria.
 This method is in early development. A one-liter sample is collected in a high-density polypropylene bottle containing sodium thiosulfate for dechlorination. The sample is decontaminated for 30 minutes with 0.4% cetylpyridinium chloride solution. Then, 500 mL of the decontaminated sample is vacuumed filtered through a 0.45 mm black, mixed cellulose membrane. The membrane with the captured bacteria is laid on top of Middlebrook 7H11 agar plate. The plate is incubated at 37 °C for 7 days. The resulting colonies are chosen for matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) identification. The EPA invites comments to support development of this method. The agency is particularly interested in the following: (1) suggestions for preservation chemical to use; (2) input on detection limits using MALDI-MS; (3) input on the sample volume needed; and (4) feedback regarding any experience with this technique. 6. Draft EPA Method 
                    *Mycobacterium*
                     qPCR—
                    *Mycobacterium avium*
                     and 
                    *Mycobacterium intracellulare*
                     quantitative polymerase chain reaction (qPCR) detection. The target contaminants for this method are shown in Exhibit 10. Exhibit 10—Target Contaminants in Draft EPA Method Mycobacterium QPCR
Microorganism
Type of microorganism*Mycobacterium avium*
Bacteria.*Mycobacterium intracellulare*
Bacteria.
 This method can distinguish between 
                    *Mycobacterium avium*
                     and 
                    *Mycobacterium intracellulare*
                     species. For this method, a one-liter sample is collected in a high-density polypropylene bottle containing sodium thiosulfate for dechlorination. The sample is vacuum-filtered through a 0.45 μm polycarbonate membrane. The captured microbial DNA is extracted from the membrane. The extracted DNA is analyzed using two qPCR assays utilizing a qPCR instrument. This method will detect and quantify the targeted microbe of interest. The method identifies the target bacteria using primer-probe specific to the microbe of interest, and the resulting qPCR gene product (DNA sequence) molecular weight is checked. The instrument will generate an amplification curve if the targeted bacteria is present in a sample. As the curve passes the 0.4 threshold, a Cq value is determined. The targeted bacteria DNA (Cq value) is then quantified using a standard curve generated from genomic DNA. The method contains other QC samples, including positive controls such as the standard curve, and negative controls such as internal controls, method blanks, extraction blanks, and non-template controls. This method requires the collection of a 200 mL water sample. The EPA invites comments to support development of this method. The agency is particularly interested in information on environmental laboratory capabilities to perform this method. C. What other drinking water analytical methods are being considered by the EPA to address emerging contaminants? 1. Draft EPA Method EOF—Screening method for the determination of extractable organic fluorine (EOF) in drinking water by anion exchange solid phase extraction and combustion ion chromatography (CIC). The target contaminant for this method is Extractable Organic Fluorine (EOF). Targeted PFAS drinking water methods currently only capture a small subset of the many PFAS known to exist. “Aggregate” methods (sometimes referred to as a “total PFAS” method) are designed to capture a larger portion of the PFAS than targeted methods are able to detect. The subject technique seeks to estimate the concentration of EOF in drinking water. It captures organofluorine compounds from PFAS and non-PFAS fluorinated substances that are retained using weak anion exchange SPE. The method has potential application for screening, recognizing that it will not measure fluorinated compounds individually, but as an aggregate sum of the fluorinated compounds captured on the sorbent. Notably, non-PFAS fluorinated compounds may also be accounted for in the reported value along with residual inorganic fluoride that is added to drinking water to prevent tooth decay. For this EOF method in development by the EPA, the preservation scheme follows EPA Method 533, with the aqueous samples preserved with ammonium acetate to sequester free chlorine to form chloramine. Additionally, the EOF method follows the EPA Method 533 holding time scheme set at 28 days. The drinking water sample is concentrated using weak anion-exchange SPE. After passing the sample through the SPE cartridge, preserved reagent water is pulled through the cartridge, then aqueous ammonium hydroxide is used to wash the SPE cartridge to remove inorganic fluoride. A solution of ammonium hydroxide in methanol is used to elute the adsorbed compounds. The extract is evaporated to dryness and reconstituted in a methanol and water mixture. The entire extract is transferred to a ceramic boat and combusted at high temperature in the furnace of a combustion ion chromatography (CIC) instrument to break the carbon-fluorine bond. The released fluorine is absorbed in a water solution to form the fluoride ion. A portion of the fluoride solution is separated by ion chromatography using a potassium hydroxide-based eluent. External calibration is used to establish the retention time for fluoride and report the extractable organic fluorine as fluoride. The agency notes that aggregate techniques considered to-date do not have the same sensitivity as targeted techniques. The quantitation capabilities of the EOF technique, and the suitability of the technique for drinking water monitoring, continue to be evaluated. The agency considered other aggregate methods, including an 
                    ( print page 8594)
                    adsorbable organic fluorine (AOF) procedure, such as draft EPA Method 1621 (USEPA, 2022a). In the AOF method, larger samples achieve better sensitivity. The agency notes that draft EPA Method 1621 does not retain short carbon PFAS within the data quality objective limits of 70-130%. In addition, draft EPA Method 1621 does not permit rinsing of the sample container, meaning hydrophobic PFAS may be lost to adsorption on the sample container. A method wash step removes inorganic fluoride up to 95%, but a trace amount of inorganic fluoride may remain because of the weak anion exchange sorbent. The EPA invites comments to support development and consideration of aggregate PFAS measurement. The agency is particularly interested in the following: (1) techniques to extract or adsorb ultra short chain PFAS; (2) alternative ways to remove inorganic fluoride from aqueous drinking water samples prior to or during the extraction or adsorption for organic fluoride; (3) techniques to capture anionic, neutral and cationic PFAS in a single solid phase extraction procedure; and (4) techniques to improve the selectivity of the extraction process to reduce or eliminate retention of non-PFAS fluorinated compounds. 2. Draft EPA Method Microplastics—Analysis of microplastics in drinking water using spectroscopic instrumentation. The target contaminant for this method is “microplastics.” Common spectroscopic libraries contain spectra for thousands of different polymers that can all be identified using these instruments. For this discussion, EPA's water research definition of microplastics is particles ranging in size from 5 millimeters (mm) to 1 mm at 
                    *https://www.epa.gov/​water-research/​microplastics-research.* The agency is in the early stages of developing a microplastics method and is gathering information about analytical approaches. The agency recognizes that voluntary consensus standards bodies (VCSBs) methods ASTM D8332-20 and ASTM D8333-20 are available. This section summarizes the currently available research. In developing the final method approach, the agency will seek to incorporate the latest advancements in microplastic research and analytical methodologies. There are a variety of spectroscopic techniques that can be utilized for microplastic analysis, including fourier transform infrared (FTIR) spectroscopy, laser direct infrared (LDIR) spectroscopy, and Raman spectroscopy. The analytical instruments associated with these techniques have more similarities than differences and all provide similar information to characterize microplastics, including size, shape, and polymer type of individual microplastics. For all of the spectroscopy techniques examined by the agency, samples are stored at 4 degrees Celsius (Wong and Coffin, 2022) or have a maximum of one freeze and thaw cycle (ITRC, 2023). Depending on the requirements and capabilities of the analytical instrument, a variety of instrument filter types with different coatings and pore sizes have been used to collect microplastics from aqueous samples. For example, the LDIR imaging system uses gold-coated filters that are infrared-reflective. The California State Water Resources Control Board does not recommend density separation or digestion for drinking water samples (Wong and Coffin, 2022). Spectroscopic methods only quantify the number of particles, not a mass of polymer, and can identify even a single particle on a filter, so the measurement capability is only related to the size of the particle. Many infrared and Raman-based instruments can identify particles with a minimum diameter of 20 microns and 1-micron, respectively. However, the minimum size for reliable identification on the widest range of instrument models should be considered as 50 microns for infrared-based instruments and 20 microns for Raman-based instruments. (Wong and Coffin, 2022). The EPA invites comments to support the development of a microplastics method. The agency is specifically interested in comments that will help identify the changes to microplastics that happen as a result of reactions to environmental exposures (
                    *i.e.,*
                     sunlight, water, and temperature) and how these changes can affect reliable polymer identification. D. What information should the public provide when submitting comments about drinking water analytical methods for CCL 5 and other emerging contaminants? The EPA welcomes comments from the public regarding analytical methods for measuring emerging contaminants in drinking water. This includes methods already published by the agency or others, those under development by the agency or others, and those that should be considered for future development. The agency is particularly interested in methods that may be used to monitor drinking water for the contaminants published on final the CCL 5 (87 FR 68060, November 14, 2022 (USEPA, 2022b)). The agency encourages commenters to include their name, affiliation, phone number, mailing address, and email address. However, this information is not required, and comments can be submitted anonymously. When addressing non-EPA or voluntary consensus standards bodies (VCSBs) methods, comments should address the following, as applicable: 1. Specify the method name and describe, at least generally, the instrumentation upon which it relies. 2. Specify the status of the method (
                    *e.g.,*
                     fully-developed, nearing completion, early development). 3. Specify the emerging contaminant(s), particularly the CCL contaminants, that can be analyzed with the drinking water analytical method. CCL 5 contaminants are listed in Exhibits 1-5 of this notice and at 
                    *https://www.federalregister.gov/​documents/​2022/​11/​14/​2022-23963/​drinking-water-contaminant-candidate-list-5-final.* 4. Specify method performance information, such as sensitivity, selectivity, accuracy, and precision attainable for the contaminant(s). Describe the degree to which the method performance has been validated; the latter is important for any method being considered by the EPA for UCMR or other purposes. Guidelines for analytical method validation are described by the EPA Forum on Environmental Measurement (FEM) in documents available through the FEM website (USEPA, 2016b, c) at 
                    *https://www.epa.gov/​measurements-modeling/​method-validation-and-peer-review-policies-and-guidelines.* 5. To the extent possible, specify the cost, availability, and your laboratory's capacity to run the method commercially. 6. Provide complete citations for referenced analytical methods, including author(s), title, journal (or other publication), and date. 7. Provide contact information for the principal investigator, when available. IV. References (i) Anisuzzaman, A., Storehalder, T., Williams, D., Ogg, N., Kilbourne, T., John Samuel, J., & Cottrell, C. 2008. Effect of Alcohols on the Stability of Iprodione in Solution. 
                        *Journal of Agricultural and Food Chemiemergingstry,*
                         56 (2), 502-506. DOI: 10.1021/jf0720483. (ii) ASTM. 2015. ASTM D3558-15—
                        *Standard Test Methods for Cobalt in Water.*
                         ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428. Approved February 1, 2015. Available for purchase at 
                        *astm.org*. (iii) ASTM. 2017a. ASTM D5175-91—
                        *Standard Test Method for Organohalide 
                            ( print page 8595)
                            Pesticides and Polychlorinated Biphenyls in Water by Microextraction and Gas Chromatography.*
                         ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428. Approved December 15, 2017. Available for purchase at 
                        *astm.org*. (iv) ASTM. 2017b. ASTM D5315-04—
                        *Standard Test Method for Determination of N-Methyl-Carbamoyloximes and N-Methylcarbamates in Water by Direct Aqueous Injection HPLC with Post-Column Derivatization.*
                         ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428. Approved December 15, 2017. Available for purchase at 
                        *astm.org*. (v) ASTM. 2018a. ASTM D6581-18—
                        *Standard Test Methods for Bromate, Bromide, Chlorate, and Chlorite in Drinking Water by Suppressed Ion Chromatography.*
                         ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428. Approved May 1, 2018. Available for purchase at 
                        *astm.org*. (vi) ASTM. 2018b. ASTM D5790-18—
                        *Standard Test Method for Measurement of Purgeable Organic Compounds in Water by Capillary Column Gas Chromatography/Mass Spectrometry.*
                         ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428. Approved December 15, 2018. Available for purchase at 
                        *astm.org*. (vii) ASTM. 2019. ASTM D5246-19—
                        *Standard Test Method for Isolation and Enumeration of Pseudomonas aeruginosa from Water.*
                         ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428. Approved December 1, 2019. Available for purchase at 
                        *astm.org*. (viii) ASTM. 2020a. ASTM D1976-20—
                        *Standard Test Method for Elements in Water by Inductively Coupled Plasma Atomic Emission Spectroscopy.*
                         ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428. Approved May 1, 2020. Available for purchase at 
                        *astm.org*. (ix) ASTM. 2020b. ASTM D8332-20— 
                        *Standard Practice for Collection of Water Samples with High, Medium, or Low Suspended Solids for Identification and Quantification of Microplastic Particles and Fibers.*
                         ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428. Approved July 15, 2020. Available for purchase at 
                        *astm.org*. (x) ASTM. 2020c. ASTM D8333-20— 
                        *Standard Practice for Collection of Water Samples with High, Medium, or Low Suspended Solids for Identification and Quantification of Microplastic Particles and Fibers Using Ramen Spectroscopy, IR Spectroscopy, or Pyrolysis-GC/MS.*
                         ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428. Approved July 15, 2020. Available for purchase at 
                        *astm.org*. (xi) ASTM. 2021. ASTM D8429-21—
                        *Standard Test Method for Legionella pneumophila in Water Samples Using Legiolert.*
                         ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428. Approved 2021. Available for purchase at 
                        *astm.org*. (xii) ASTM. 2023. ASTM D7645-23—
                        *Standard Test Method for Determination of Aldicarb, Aldicarb Sulfone, Aldicarb Sulfoxide, Carbofuran, Methomyl, Oxamyl, and Thiofanox in Water by Liquid Chromatography/Tandem Mass Spectrometry (LC/MS/MS).*
                         ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428. Approved April 15, 2023. Available for purchase at 
                        *astm.org*. (xiii) Bichon, E., Guiffard, I., Vénisseau, A., Marchand, P., Antignac, J.P., & Le Bizec, B. 2015. Ultra-trace quantification method for chlordecone in human fluids and tissues. 
                        *Journal of Chromatography A,*
                         1408, 169-177. 
                        *DOI.org/10.1016/j.chroma.2015.07.013.* (xiv) ISO Online. 2017. 11731:2017—Water Quality—Enumeration of 
                        *Legionella. ISO Standards.*
                         Available for purchase at 
                        *https://www.iso.org/​standards.html.* (xv) ISO Online. 2019. 12869:2019—Water quality—Detection and quantification of 
                        *Legionella*
                         spp. and/or 
                        *Legionella pneumophila*
                         by concentration and genic amplification by quantitative polymerase chain reaction (qPCR). ISO Standards. Available for purchase at 
                        *https://www.iso.org/​standards.html.* (xvi) Interstate Technology Regulatory Council (ITRC). 2023. 
                        *Microplastics Outreach Toolkit—Sampling and Analysis.*
                         February 2023. Available at 
                        *https://mp-1.itrcweb.org/​sampling-and-analysis/​.* (xvii) SM Online. 1997a. 3500-V—Vanadium (Editorial Revisions, 2020). 
                        *Standard Methods Online.*
                         Available for purchase at 
                        *http://www.standardmethods.org.* (xviii) SM Online. 1997b. 6200—Volatile Organic Compounds Method (Editorial Revisions, 2011 and 2020). 
                        *Standard Methods Online.*
                         Available for purchase at 
                        *http://www.standardmethods.org.* (xix) SM Online. 1999a. 3111—Metals by Flame Atomic Absorption Spectrometry Method (Editorial Revisions, 2019). 
                        *Standard Methods Online.*
                         Available for purchase at 
                        *http://www.standardmethods.org.* (xx) SM Online. 1999b. 3120—Metals by Plasma Emission Spectroscopy Method (Editorial Revisions, 2020). 
                        *Standard Methods Online.*
                         Available for purchase at 
                        *http://www.standardmethods.org.* (xxi) SM Online. 1999c. 3500-Mn—Manganese (Editorial Revisions, 2020). 
                        *Standard Methods Online.*
                         Available for purchase at 
                        *http://www.standardmethods.org.* (xxii) SM Online. 2000a. 4110—Determination of Anions by Ion Chromatography Method (Editorial Revisions, 2020). 
                        *Standard Methods Online.*
                         Available for purchase at 
                        *http://www.standardmethods.org.* (xxiii) SM Online. 2000b. 4500-B—Boron (Editorial Revisions, 2020). 
                        *Standard Methods Online.*
                         Available for purchase at 
                        *http://www.standardmethods.org.* (xxiv) SM Online. 2004a. 3500-Li—Lithium (Editorial Revisions, 2020). 
                        *Standard Methods Online.*
                         Available for purchase at 
                        *http://www.standardmethods.org.* (xxv) SM Online. 2004b. 6610—Carbamate Pesticides Method (Editorial Revisions, 2021). 
                        *Standard Methods Online.*
                         Available for purchase at 
                        *http://www.standardmethods.org.* (xxvi) SM Online. 2005. 6252—Disinfection Byproducts: Aldehydes Method (Proposed) (Editorial Revisions, 2020). 
                        *Standard Methods Online.*
                         Available for purchase at 
                        *http://www.standardmethods.org.* (xxvii) SM Online. 2007a. 6251—Disinfection Byproducts: Haloacetic Acids and Trichlorophenol Method (Editorial Revisions, 2020). 
                        *Standard Methods Online.*
                         Available for purchase at 
                        *http://www.standardmethods.org.* (xxviii) SM Online. 2007b. 6450—Nitrosamines Method (Editorial Revisions, 2021). 
                        *Standard Methods Online.*
                         Available for purchase at 
                        *http://www.standardmethods.org.* (xxix) SM Online. 2007c. 9213—Recreational Waters (Editorial Revisions, 2022). 
                        *Standard Methods Online.*
                         Available for purchase at 
                        *http://www.standardmethods.org.* (xxx) SM Online. 2010. 3113—Metals by Electrothermal Atomic Absorption Spectrometry Method (Editorial Revisions, 2020). 
                        *Standard Methods Online.*
                         Available for purchase at 
                        *http://www.standardmethods.org.* (xxxi) SM Online. 2013. 6810—Pharmaceuticals and Personal Care Products Method (Editorial Revisions, 2021). 
                        *Standard Methods Online.*
                         Available for purchase at 
                        *http://www.standardmethods.org.* (xxxii) SM Online. 2021. 9750—Detection of 
                        *Naegleria fowleri*
                         in Water. 
                        *Standard Methods Online.*
                         Available for purchase at 
                        *http://www.standardmethods.org.* (xxxiii) USEPA. 1992a. 
                        *Method 552.1—Determination of Haloacetic Acids and Dalapon in Drinking Water by Ion-Exchange Liquid-Solid Extraction and Gas Chromatography with an Electron Capture Detector.*
                         Revision 1.0. Office of Research and Development, Cincinnati, OH. August 1992. Available at 
                        *https://www.nemi.gov/​methods/​method_​summary/​4784/​.* (xxxiv) USEPA. 1992b. 
                        *Method 554—Determination of Carbonyl Compounds in Drinking Water by Dinitrophenylhydrazine Derivatization and High Performance Liquid Chromatography.*
                         Revision 1.0. Office of Research and Development, Cincinnati, OH. August 1992. Available at 
                        *https://www.nemi.gov/​methods/​method_​summary/​12611/​.* (xxxv) USEPA. 1994a. 
                        *Method 200.7—Determination of Metals and Trace Elements in Water and Wastes by Inductively Coupled Plasma-Atomic Emission Spectrometry.*
                         Revision 4.4. Office of Research and Development, Cincinnati, OH. 1994. Available at 
                        *https://www.epa.gov/​esam/​method-2007-determination-metals-and-trace-elements-water-and-wastes-inductively-coupled-plasma.* (xxxvi) USEPA. 1994b. 
                        *Method 200.8—Determination Trace Elements in Waters and Wastes by Inductively Coupled Plasma-Mass Spectrometry.*
                         Revision 5.4. Office of Research and Development, Cincinnati, OH. 1994. Available at 
                        *https://www.epa.gov/​sites/​default/​files/​2015-06/​documents/​epa-200.8.pdf.*( print page 8596) (xxxvii) USEPA. 1994c. 
                        *Method 200.9—Determination of Trace Elements by Stabilized Temperature Graphic Furnace Atomic Absorption.*
                         Revision 2.2. Office of Research and Development, Cincinnati, OH. 1994 Available at 
                        *https://www.epa.gov/​sites/​default/​files/​2015-08/​documents/​method_​200-9_​rev_​2-2_​1994.pdf.* (xxxviii) USEPA. 1995a. 
                        *Method 502.2—Volatile Organic Compounds in Water by Purge and Trap Capillary Column Gas Chromatography with Photoionization and Electrolytic Conductivity Detectors in Series.*
                         Revision 2.1. Office of Research and Development, Cincinnati, OH. 1995. Available at 
                        *https://www.nemi.gov/​methods/​method_​summary/​4827/​.* (xxxix) USEPA. 1995b. 
                        *Method 504.1—1,2-Dibromoethane (EDB), 1,2-Dibromo-3-Chloro-Propane (DBCP), and 1,2,3-Trichloropropane (123TCP) in Water by Microextraction and Gas Chromatography.*
                         Revision 1.1. Office of Research and Development, Cincinnati, OH. 1995. Available at 
                        *https://www.nemi.gov/​methods/​method_​summary/​4825/​.* (xl) USEPA. 1995c. 
                        *Method 505—Analysis of Organohalide Pesticides and Commercial Polychlorinated Biphenyl (PCB) Products in Water by Microextraction and Gas Chromatography.*
                         Revision 2.1. Office of Research and Development, Cincinnati, OH. 1995. Available at 
                        *https://www.nemi.gov/​methods/​method_​summary/​4799/​.* (xli) USEPA. 1995d. 
                        *Method 507—Determination of Nitrogen and Phosphorus Containing Pesticides in Water by Gas Chromatography with a Nitrogen-Phosphorus Detector.*
                         Revision 2.1. Office of Research and Development, Cincinnati, OH. 1995. Available at 
                        *https://www.nemi.gov/​methods/​method_​summary/​4801/​.* (xlii) USEPA. 1995e. 
                        *Method 508—Determination of Chlorinated Pesticides in Water by Gas Chromatography with an Electron Capture Detector.*
                         Revision 3.1. Office of Research and Development, Cincinnati, OH. 1995. Available at 
                        *https://www.nemi.gov/​methods/​method_​summary/​4826/​.* (xliii) USEPA. 1995f. 
                        *Method 508.1—Determination of Chlorinated Pesticides, Herbicides, and Organohalides by Liquid-Solid Extraction and Electron Capture Gas Chromatography.*
                         Revision 2.0. Office of Research and Development, Cincinnati, OH. 1995. Available at 
                        *https://www.nemi.gov/​methods/​method_​summary/​4802/​.* (xliv) USEPA. 1995g. 
                        *Method 524.2—Measurement of Purgeable Organic Compounds in Water by Capillary Column Gas Chromatography/Mass Spectrometry.*
                         Revision 4.1. Office of Research and Development, Cincinnati, OH. 1995. Available at 
                        *https://www.epa.gov/​sites/​default/​files/​2015-06/​documents/​epa-524.2.pdf.* (xlv) USEPA. 1995h. 
                        *Method 525.2—Determination of Organic Compounds in Drinking Water by Liquid-Solid Extraction and Capillary Column Gas Chromatography/Mass Spectrometry.*
                         Revision 2.0. Office of Research and Development, Cincinnati, OH. 1995. Available at 
                        *https://www.epa.gov/​sites/​default/​files/​2015-06/​documents/​epa-525.2.pdf.* (xlvi) USEPA. 1995i. 
                        *Method 531.1—Measurement of N-Methylcarbamoyloximes and N-Methylcarbamates in Water by Direct Aqueous Injection HPLC with Post Column Derivatization.*
                         Revision 3.1. Office of Research and Development, Cincinnati, OH. 1995. Available at 
                        *https://www.nemi.gov/​methods/​method_​summary/​4805/​.* (xlvii) USEPA. 1995j. 
                        *Method 551.1—Determination of Chlorination Disinfection Byproducts, Chlorinated Solvents, and Halogenated Pesticides/Herbicides in Drinking Water by Liquid-Liquid Extraction and Gas Chromatography with Electron-Capture Detection.*
                         Revision 1.0. Office of Research and Development, Cincinnati, OH. 1995. Available at 
                        *https://www.epa.gov/​sites/​default/​files/​2015-06/​documents/​epa-551.1.pdf.* (xlviii) USEPA. 1995k. 
                        *Method 552.2—Determination of Haloacetic Acids and Dalapon in Drinking Water by Liquid-Liquid Extraction, Derivatization and Gas Chromatography with Electron Capture Detection.*
                         Revision 1.0. Office of Research and Development, Cincinnati, OH. 1995. Available at 
                        *https://www.nemi.gov/​methods/​method_​summary/​4787/​.* (xlix) USEPA. 1997. 
                        *Method 300.1—Determination of Inorganic Anions in Drinking Water by Ion Chromatography.*
                         Revision 1.0. Office of Research and Development, Cincinnati, OH. 1997. Available at 
                        *https://www.epa.gov/​sites/​default/​files/​2015-06/​documents/​epa-300.1.pdf.* (l) USEPA. 1999. 
                        *Method 556.1—Determination of Carbonyl Compounds in Drinking Water by Fast Gas Chromatography.*
                         Revision 1.0. Office of Research and Development, Cincinnati, OH. September 1999. Available at 
                        *https://www.epa.gov/​dwanalyticalmethods.* (li) USEPA. 2000a. 
                        *Method 526—Determination of Selected Semivolatile Organic Compounds in Drinking Water by Solid Phase Extraction and Capillary Column Gas Chromatography/Mass Spectrometry (GC/MS).*
                         Revision 1.0. Office of Research and Development, Cincinnati, OH. June 2000. Available at 
                        *https://www.epa.gov/​dwanalyticalmethods.* (lii) USEPA. 2000b. 
                        *Method 528—Determination of Phenols in Drinking Water by Solid Phase Extraction and Capillary Column Gas Chromatography/Mass Spectrometry (GC/MS).*
                         Revision 1.0. Office of Research and Development, Cincinnati, OH. April 2000. Available at 
                        *https://www.epa.gov/​dwanalyticalmethods.* (liii) USEPA. 2000c. 
                        *Method 532—Determination of Phenylurea Compounds in Drinking Water by Solid Phase Extraction and High Performance Liquid Chromatography with UV Detection.*
                         Revision 1.0. Office of Research and Development, Cincinnati, OH. June 2000. Available at 
                        *https://www.epa.gov/​dwanalyticalmethods.* (liv) USEPA. 2001. 
                        *Method 531.2—Measurement of N-Methylcarbamoyloximes and N-Methylcarbamates in Water by Direct Aqueous Injection HPLC with Postcolumn Derivatization.*
                         Revision 1.0. EPA 815-B-01-002. Office of Ground Water and Drinking Water, Cincinnati, OH. September 2001. Available at 
                        *https://www.epa.gov/​sites/​default/​files/​2015-06/​documents/​epa-531.2.pdf.* (lv) USEPA. 2003a. 
                        *Method 552.3—Determination of Haloacetic Acids and Dalapon in Drinking Water by Liquid-Liquid Microextraction, Derivatization, and Gas Chromatography with Electron Capture Detection.*
                         Revision 1.0. EPA 815-B-03-002. Office of Ground Water and Drinking Water, Cincinnati, OH. July 2003. Available at 
                        *https://nepis.epa.gov/​Exe/​ZyPDF.cgi/​901V0400.PDF?​Dockey=​901V0400.PDF.* (lvi) USEPA. 2003b. 
                        *Method 200.5—Determination of Trace Elements in Drinking Water by Axially Viewed Inductively Coupled Plasma-Atomic Emission Spectrometry.*
                         Revision 4.2. EPA 600-R-06-115. Office of Research and Development, Cincinnati, OH. October 2003. Available at 
                        *https://www.epa.gov/​sites/​default/​files/​2015-08/​documents/​method_​200-5_​rev_​4-2_​2003.pdf.* (lvii) USEPA. 2004. 
                        *Method 521—Determination of Nitrosamines in Drinking Water by Solid Phase Extraction and Capillary Column Gas Chromatography with Large Volume Injection and Chemical Ionization Tandem Mass Spectrometry (MS/MS).*
                         Version 1.0. EPA 600-R-05-054. Office of Research and Development, Cincinnati, OH. September 2004. Available at 
                        *https://www.epa.gov/​dwanalyticalmethods.* (lviii) USEPA. 2005. 
                        *Method 527—Determination of Selected Pesticides and Flame Retardants in Drinking Water by Solid Phase Extraction and Capillary Column Gas Chromatography/Mass Spectrometry (GC/MS).*
                         Revision 1.0. EPA 815-R-05-005. Office of Ground Water and Drinking Water, Cincinnati, OH. April 2005. Available at 
                        *https://www.epa.gov/​dwanalyticalmethods.* (lix) USEPA. 2007. 
                        *Method 536—Determination of Triazine Pesticides and their Degradates in Drinking Water by Liquid Chromatography Electrospray Ionization Tandem Mass Spectrometry (LC/ESI-MS/MS).*
                         Version 1.0. EPA 815-B-07-002. Office of Ground Water and Drinking Water, Cincinnati, OH. October 2007. Available at 
                        *https://nepis.epa.gov/​Exe/​ZyPDF.cgi/​P1005E35.PDF?​Dockey=​P1005E35.PDF.* (lx) USEPA. 2008. 
                        *Method 522—Determination of 1,4-Dioxane in Drinking Water by Solid Phase 
                            ( print page 8597)
                            Extraction (SPE) and Gas Chromatography/Mass Spectrometry (GC/MS) with Selected Ion Monitoring (SIM).*
                         Revision 1.0. EPA 600-R-08-101. Office of Research and Development, Cincinnati, OH. September 2008. Available at 
                        *https://www.epa.gov/​dwanalyticalmethods.* (lxi) USEPA. 2009a. 
                        *Method 524.3—Measurement of Purgeable Organic Compounds in Water by Capillary Column Gas Chromatography/Mass Spectrometry.*
                         Version 1.0. EPA 815-B-09-009. Office of Ground Water and Drinking Water, Cincinnati, OH. June 2009. Available at 
                        *https://nepis.epa.gov/​Exe/​ZyPDF.cgi/​P100J75C.PDF?​Dockey=​P100J75C.PDF.* (lxii) USEPA. 2009b. 
                        *Method 557: Determination of Haloacetic Acids, Bromate, and Dalapon in Drinking Water by Ion Chromatography Electrospray Ionization Tandem Mass Spectrometry (IC-ESI-MS/MS).*
                         Version 1.0. Office of Water, Cincinnati, OH. September 2009. Available at 
                        *https://nepis.epa.gov/​Exe/​ZyPDF.cgi/​P1005OKO.PDF?​Dockey=​P1005OKO.PDF.* (lxiii) USEPA. 2009c. 
                        *Method 538—Determination of Selected Organic Contaminants in Drinking Water by Direct Aqueous Injection-Liquid Chromatography/Tandem Mass Spectrometry (DAI-LC/MS/MS).*
                         Version 1.0. EPA 600-R-09-149. Office of Research and Development, Cincinnati, OH. November 2009. Available at 
                        *https://www.epa.gov/​dwanalyticalmethods.* (lxiv) USEPA. 2010. 
                        *Method 539—Determination of Hormones in Drinking Water by Solid Phase Extraction (SPE) and Liquid Chromatography Electrospray Ionization Tandem Mass Spectrometry (LC-ESI-MS/MS).*
                         Version 1.0. EPA 815-B-10-001. Office of Water, Cincinnati, OH. November 2010. Available at 
                        *https://www.epa.gov/​dwanalyticalmethods.* (lxv) USEPA. 2011. 
                        *Method 523—Determination of Triazine Pesticides and their Degradates in Drinking Water by Gas Chromatography/Mass Spectrometry (GC/MS).*
                         Version 1.0. EPA 815-R-11-002. Office of Water, Cincinnati, OH. February 2011. Available at 
                        *https://nepis.epa.gov/​Exe/​ZyPDF.cgi/​P100J7D4.PDF?​Dockey=​P100J7D4.PDF.* (lxvi) USEPA. 2012. 
                        *Method 525.3—Determination of Semivolatile Organic Chemicals in Drinking Water by Solid Phase Extraction and Capillary Column Gas Chromatography/Mass Spectrometry (GC/MS).*
                         Version 1.0. EPA 600-R-12-010. Office of Research and Development, Cincinnati, OH. February 2012. Available at 
                        *https://cfpub.epa.gov/​si/​si_​public_​record_​report.cfm?​Lab=​NERL&​dirEntryId=​241188.* (lxvii) USEPA. 2013a. 
                        *Method 524.4—Measurement of Purgeable Organic Compounds in Water by Gas Chromatography/Mass Spectrometry Using Nitrogen Purge*
                         Gas. EPA 815-R-13-002. Office of Water, Cincinnati, OH. May 2013. Available at 
                        *https://nepis.epa.gov/​Exe/​ZyPDF.cgi/​P100J7EE.PDF?​Dockey=​P100J7EE.PDF.* (lxviii) USEPA. 2013b. 
                        *Method 540—Determination of Selected Organic Chemicals in Drinking Water by Solid Phase Extraction and Liquid Chromatography/Tandem Mass Spectrometry (LC/MS/MS).*
                         Version 1.0. EPA 600-R-13-119. Office of Research and Development, Cincinnati, OH. September 2013. Available at 
                        *https://www.epa.gov/​dwanalyticalmethods.* (lxix) USEPA. 2014. 
                        *Method 1615—Measurement of Enterovirus and Norovirus Occurrence in Water by Culture and RT-qPCR.*
                         Version 1.3. Office of Research and Development, Cincinnati, OH. September 2014. Available at 
                        *https://cfpub.epa.gov/​si/​si_​public_​record_​report.cfm?​dirEntryId=​306930&​Lab=​NERL.* (lxx) USEPA. 2015a. 
                        *Method 530—Determination of Select Semivolatile Organic Chemicals in Drinking Water by Solid Phase Extraction and Gas Chromatography/Mass Spectrometry (GC/MS).*
                         Version 1.0. EPA 600-R-14-442. Office of Research and Development, Cincinnati, OH. January 2015. Available at 
                        *https://www.epa.gov/​dwanalyticalmethods.* (lxxi) USEPA. 2015b. 
                        *Method 544—Determination of Microcystins and Nodularin in Drinking Water by Solid Phase Extraction and Liquid Chromatography/Tandem Mass Spectrometry (LC/MS/MS).*
                         Version 1.0. EPA 600-R-14-474. Office of Research and Development, Cincinnati, OH. February 2015. Available at 
                        *https://www.epa.gov/​dwanalyticalmethods.* (lxxii) USEPA. 2015c. 
                        *Method 543—Determination of Selected Organic Chemicals in Drinking Water by On-Line Solid Phase Extraction-Liquid Chromatography/Tandem Mass Spectrometry (On-Line SPE-LC/MS/MS).*
                         Version 1.0. EPA 600-R-14-098. Office of Research and Development, Cincinnati, OH. March 2015. Available at 
                        *https://nepis.epa.gov/​Exe/​ZyPDF.cgi/​P100MD0C.PDF?​Dockey=​P100MD0C.PDF.* (lxxiii) USEPA. 2015d. 
                        *Method 545: Determination of Cylindrospermopsin and Anatoxin-a in Drinking Water by Liquid Chromatography Electrospray Ionization Tandem Mass Spectrometry (LC/ESI-MS/MS).*
                         EPA 815-R-15-009. Office of Water, Cincinnati, OH. April 2015. Available at 
                        *https://www.epa.gov/​dwanalyticalmethods.* (lxxiv) USEPA. 2015e. 
                        *Method 541: Determination of 1-Butanol, 1,4-Dioxane, 2-Methoxyethanol and 2-Propen-1-ol in Drinking Water by Solid Phase Extraction and Gas Chromatography/Mass Spectrometry.*
                         EPA 815-R-15-011. Office of Water, Cincinnati, OH. November 2015. Available at 
                        *https://nepis.epa.gov/​Exe/​ZyPDF.cgi?​Dockey=​P100NGIF.txt.* (lxxv) USEPA. 2016a. 
                        *Method 600/R-16/114-Analytical Protocol for Measurement of Extractable Semivolatile Organic Compounds Using Gas Chromatography/Mass Spectrometry.*
                         Office of Research and Development, Cincinnati, OH. July 2016. Available at 
                        *https://cfpub.epa.gov/​si/​si_​public_​record_​report.cfm?​dirEntryId=​337629&​Lab=​NHSRC.* (lxxvi) USEPA. 2016b. 
                        *Method Validation of U.S. Environmental Protection Agency (EPA) Microbiological Methods of Analysis.*
                         FEM Document Number 2009-01. December 2016. Available at 
                        *https://www.epa.gov/​measurements-modeling/​method-validation-and-peer-review-policies-and-guidelines.* (lxxvii) USEPA. 2016c. 
                        *Validation and Peer Review of U.S. Environmental Protection Agency Chemical Methods of Analysis.*
                         FEM Document Number 2005-01. February 2016. Available at 
                        *https://www.epa.gov/​measurements-modeling/​method-validation-and-peer-review-policies-and-guidelines.* (lxxviii) USEPA. 2019a. 
                        *Method 533: Determination of Per- and Polyfluoroalkyl Substances in Drinking Water by Isotope Dilution Anion Exchange Solid Phase Extraction and Liquid Chromatography/Tandem Mass Spectrometry.*
                         EPA 815-B-19-020. Office of Water, Cincinnati, OH. November 2019. Available at 
                        *https://www.epa.gov/​dwanalyticalmethods.* (lxxix) USEPA. 2019b. 
                        *Technical Brief Innovative Research for a Sustainable Future: Perfluoroalkyl and Polyfluoroalkyl Substances (PFAS) Methods and guidance for sampling and analyzing water and other environmental media.*
                         EPA 600-F-17-022g. Office of Research and Development, Cincinnati, OH. March 2010. Available at 
                        *https://www.epa.gov/​sites/​default/​files/​2019-12/​documents/​pfas_​methods-sampling_​tech_​brief_​23dec19_​update.pdf.* (lxxx) USEPA. 2020a. 
                        *Method 537.1: Determination of Selected Per- and Polyfluorinated Alkyl Substances in Drinking Water by Solid Phase Extraction and Liquid Chromotography/Tandem Mass Spectrometry (LC/MS/MS).*
                         Version 2.0. EPA 600-R-20-006. Office of Research and Development, Cincinnati, OH. March 2010. Available at 
                        *https://cfpub.epa.gov/​si/​si_​public_​record_​report.cfm?​dirEntryId=​348508&​Lab=​CESER&​simpleSearch=​0&​showCriteria=​2&​searchAll=​537.1&​TIMSType=​&​dateBeginPublishedPresented=​03%2F24%2F2018.* (lxxxi) USEPA. 2020b. 
                        *Method 559—Determination of Nonylphenol and 4-Tert-Octylphenol in Drinking Water by Solid Phase Extraction and Liquid Chromatography/Tandem Mass Spectrometry (LC/MS/MS).*
                         Version 1.0. EPA 600-R-20-270. Office of Research and Development, Cincinnati, OH. September 2020. Available at 
                        *https://cfpub.epa.gov/​si/​si_​public_​record_​report.cfm?​Lab=​CESER&​dirEntryId=​349691.* (lxxxii) USEPA. 2022a. 
                        *Draft Method 1621: Screening Method for the Determination of Adsorbable Organic Fluorine (AOF) in Aqueous Matrices by Combustion Ion 
                            ( print page 8598)
                            Chromatography (CIC).*
                         EPA-821-D-22-0202. Office of Research and Development, Cincinnati, OH. April 2022. Available at 
                        *https://www.epa.gov/​system/​files/​documents/​2022-04/​draft-method-1621-for-screening-aof-in-aqueous-matrices-by-cic_​0.pdf.* (lxxxiii) USEPA. 2022b. Drinking Water Contaminant Candidate List 5—Final. 
                        **Federal Register**
                        . Vol. 87, No. 218, p. 68060, November 14, 2022. (lxxxiv) USEPA. 2023. Comptox Chemicals Dashboard v2.3.0. 
                        *https://comptox.epa.gov/​dashboard/​chemical-lists/​PFASSTRUCT*
                         (accessed January 24, 2024) PFAS Structure Lists. (lxxxv) Wong, C. & Coffin, S. 2022. 
                        *Standard Operating Procedures for Extraction and Measurement by Infrared Spectroscopy of Microplastic Particles in Drinking Water.*
                         California State Water Resources Control Board. May 27, 2022. Available at 
                        *https://www.waterboards.ca.gov/​drinking_​water/​certlic/​drinkingwater/​documents/​microplastics/​swb-mp1-rev1.pdf.* Jennifer L. McLain, Director, Office of Ground Water and Drinking Water.


[FR Doc. 2024-02247 Filed 2-7-24; 8:45 am] BILLING CODE P