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Standard Interpretations, Implementation Guidance, and Guidance Documents

TNI has established an avenue for resolution of questions submitted electronically on interpretation of the 2003 NELAC and 2009 and 2016 TNI Standards. The method for submittal is to complete an on-line form (available here). Use of this entry form ensures that a question is automatically accepted, cataloged and emailed to the NELAP Accreditation Council Chair, the LAS Executive Committee Chair and the TNI Program Administrator for review. A consensus of these three individuals shall determine who oversees the final disposition of the question. Timelines are defined for the NELAP Accreditation Council Chair and LAS Executive Committee Chair to ensure a timely response to the question. Publication of the consensus resolution is then made to the affected parties via email and on this page. These interpretations are organized by each Standard (2003, 2009, and 2016) and then by section number.

Some of the older interpretations are still applicable to the 2016 Standard; others are not.  TNI has prepared a consolidated document with all interpretations that relate to Volume 1 of the 2016 standard.

Some SIR submissions are valid questions but do not meet the criteria to be a SIR. Those are being treated as clarification requests and are now addressed with answers termed “Implementation Guidance" that are posted below.

Three Guidance Documents relating to Proficiency Testing Reporting Limits, Instrument Calibration, and Limit of Detection and Limit of Quantitation have been developed to assist with implementation of the 2016 Standard.

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Section Subject Date
V1M2, Section 4.3.1 and Laboratory Copy of TNI Standard 10/13/20
V1M2, Section (f) Technical manager education and experience for radon 02/11/19
V1M4, Section MDL Requirements 05/20/20
V1M4, Section 1.6.1 (c) Demonstration of Capability 01/19/21
V1M4, Section 1.6.3 Demonstration of Capability Requirements 01/19/21
V1M4, Section 1.6.3 Alternate Approaches to Ongoing Demonstration of Capability 06/03/21
V1M4, Section Demonstration of Capability - Use of Marginal Exceedance Limits 01/19/21
V1M4, Section Initial Calibration Second Source Verification of Surrogates or Internal Standards 06/03/21
V1M4, Section (k) Calibration Standard Requirements 05/20/20
V1M5, Section (a) Checking Materials and Supplies 12/11/19
V1M5, Section Variability/Reproducibility of Quanti-Tray 10/13/20
Section Subject Date
V1M1, Section 4.2.1 Proficiency Testing, Methods and Technologies 08/16/18
V1M1, Section 4.2.1 Analysis Date for PT Samples 10/05/14
V1M1, Section 4.2.1 (a) Analysis Date for PT Samples 03/13/14
V1M1, Section 6.1 (b) and V1M2 8.2 (c) Corrective Action Date for PTs 10/05/14
V1M1, Section 7.7.3; V2M3, Section 5.1 Reassessment Requirements 04/07/13
V1M2, Section and (a) Technical Director Requirements 03/13/14
V1M4, Section Demonstration of Capability (DOC) 04/07/13
V1M2, Section 4.14.1 Method Selection for Internal Audits 01/16/18
V1M2, Section Technical Manager Experience 08/16/18
V1M2, Section (a) and (b) Technical Director Experience 04/07/14
V1M2, Section (c) Technical Manager Education Requirements 11/28/16
V1M2, Section (c) Technical Manager Qualifications 05/20/20
V1M2, Section 5.4.2 Selection of Methods 12/29/11
V1M2, Section 5.4.2 Selection of Methods 10/05/14
V1M2, Section Verification of Disposable Volumetric Dispensing Devices 11/28/16
V1M2, Section Checking Accuracy of Plasticware 02/23/17
V1M2, Section (b) Thermometer Correction Factors 08/16/18
V1M2, Section (e) Syringe Quarterly Checks 08/16/18
V1M2, Section (e) Accuracy Checks of Non-Class A Glassware 01/16/18
V1M2, Section (b) Calibration of Support Equipment 10/05/14
V1M2, Section Certificates of Analysis 04/07/13
V1M2, Section Documentation and Traceability of Consumables 03/13/14
V1M2, Section (d) Traceability of Reagents 10/13/15
V1M2, Section 5.8.5 (a) Sample Container Identification 06/11/19
V1M4, Section Limit of Detection (LoD) Requirement 02/10/14
V1M4, Section 1.5.4 Second Column Confirmation of PT Results 03/13/14
V1M4, Section 1.6.2 and 1.6.3 Demonstration of Capability Requirements 01/19/21
V1M4, Section 1.6.2-1.6.3 Demonstration of Capability for Work Cells 03/13/14
V1M4, Section and (b) Marginal Exceedences and IDOCs 03/13/14
V1M4, Section LCS Requirements 06/11/19
V1M4, Section and Note LCS Requirements 05/20/20
V1M4, Section Matrix Spike in place of LCS 06/11/19
V1M4, Section Matrix Duplicate Precision 02/10/14
V1M5, Section Methods that Specify Colony Counts 01/16/18
V1M5, Section (c) Reagent Water 10/13/15
V1M4, Section (r) Microbiological Sample Handling 04/07/13
V1M6, Section 1.5.4 Precision and Uncertainty 10/14/13
V1M6, Section 1.7.1 (a) Calibration of Gamma Detectors 01/07/14
V2M1, Section 6.0 (ISO 17011:2004(E) 6.2.3) Specific Scopes for Assessors 01/16/18
V2M1 (7.7.2-7.7.3) and V2M3 (6.13.2) Reassessments and Surveillance Audits 09/12/13
V2M1, V2M3: 8.2.1 (b) and 7 (b) Key Personnel 10/05/14
V2M2 PT for Biological Testing 10/13/15
V2M2, Section 4.1.1 (f) Secondary AB Notification of Revocation of Lab Accreditation 01/16/18
V2M2, Section 6.3 Multiple Preparation Methods for PTs 10/05/14
V2M3, Section 4.2.4 Assessor Training Requirements 02/10/14
Section Subject Date
2 SCM FoPT (7/1/07); FoPT Table - NELAC Analyte 1935, Footnote 13 01/18/12
2 FoPT Table - List of Analytes Requiring PTs 10/16/17
2 Proficiency Testing - evaluation of less than "<" results 10/12/09
2.2.1, Appendix C.3 PT Result Acceptability Below the PTRL 07/26/11
2.5 Requirements for Laboratory Testing of PT Study Samples 07/26/11
2.6 Evaluation of Proficiency Testing Results 10/12/09 (d) Supplemental PT Studies for Demonstating Corrective Action (PCB exception) 10/12/09 Data Integrity Procedures 03/10/11 Controlled Documents 04/07/14 (b) Frequency of Document Review 01/25/09 Subcontrator Lab Documentation 11/08/12, (b), (d), (a) Initial Calibration Verification (ICV) Acceptance 04/07/14
5.4.12 Chain of Custody Requirements 04/07/14 Technical Records 01/25/09 Internal Audits 03/29/12,, Chapter 5 Appendix C.1, Chapter 5 Appendix C.2 Certification Statement for Demonstration of Capability 07/26/11 (c) Demonstration of Capability Requirements 10/13/15 Standard Operating Procedures (SOPs) 01/25/09 Demonstration of Capability 01/25/09, Appendix A Biological Tissue QC Matrix 11/08/12;; Appendix C3.3 (b) Non-standard methods / modification of methods 02/22/09 Estimation of Uncertainty of Measurement 01/18/12 (b) Calibration of NIST-traceable References 04/07/14 (h) Calibration Range for pH 10/05/14 (d) Definition of a second source standard 02/22/09 (d) Second Source Calibration Standards 10/05/14 (d) Initial Instrument Calibration (ICAL) - second source for surrogates 10/26/09 Electronic instrument maintenance records 10/26/09 Labeling of Calibrated Equipment 04/16/12 Instrument Calibration - CCVs 01/25/09 Initial Calibration Verification 07/17/11 Reference Standards 03/12/12 Certificate of Analysis for Reagents 04/07/13 (c) Documentation and Labeling of Standards, Reagents, and Reference Materials 07/26/11 Sample Receipt Protocols 10/26/09 Sample Acceptance Plan - communication frequency 10/26/09
5.5.10 Reporting Results 07/26/11
5.5.10 LOD and LOQ in Test Reports 02/23/17 (i) Test Reports - dry or wet weight notations 01/25/09 Identification of Test Method on Test Reports 02/10/13
Appendix B.2.1 and B.2.2 RSD of verification analyses / QC check of assigned value 10/26/09
Appendix C.1 Demonstration of Capability 01/25/09
Appendix C.1 (a), C.3.1, C.3.2 Outside Source vs Secondary Source 11/28/16
Appendix C.1 (e) Demonstration of Capability 02/22/09
Appendix.C.3.1 and C.3.2 Limit of Quantitation (LOQ) Criteria 09/22/14
Appendix C.3.1 Limit of Detection (LOD) 04/07/13
Appendix C.3.5 Limit of Detection (LOD) / Limit of Quantitation (LOQ) 02/10/13
Appendix C.3.1 (b) Limit of Detection (LOD) Verification 07/26/11
Appendix C.3.1 (b) Limit of Detection (LOD) 01/25/09
Appendix C.3.2 Limit of Quantitation (LOQ) 03/12/12
Appendix C.3.2 (c) Confirmation of the Limit of Quantitation (LOQ) 02/10/13
Appendix D.1.1.1 (c) Method Blank Composition 11/28/16
Appendix D. Control Limits including Zero 01/25/09
Appendix D. (c) Evaluation Criteria and Corrective Action 09/18/12
Appendix D. (c) The laboratory does not include all target analytes in the matrix spike mixture over a 2-year period. 01/25/09
Appendix D.1.2.1 MDL determination and the Method Update Rule (MUR) 02/22/09
Appendix D.1.2.1 (b) Comparison of LOD with Blank 10/14/13
Appendix D.1.2.1 (c) The laboratory must have established procedures to relate LOD with LOQ. 01/25/09
Appendix D.1.6 (a) Constant and Consistent Test Conditions 02/22/09
Appendix D.2.8 (s) Holding Time for Effluents 03/12/12
Appendix D.3.1 Microbiological tests - positive sample verification 10/26/09
Appendix D.3.1.a.5 Microbiology, Sterility Checks and Blanks 04/09/12
Appendix D.3.1(a)(2) Microbiology, Sterility Checks and Blanks 01/18/11
Appendix D.3.8.b.2)iv) Autoclave Maintenance 03/29/12
Appendix D.4.4c.3 Radiation, Count Times of Background Measurements 04/07/13
Appendix E.3.2.1 / Chapter 2 2.6 PT evaluations for microbiological data 10/26/09
Appendix F.2.1, F.2.2, F.3 PT Requirements for WET Analysis 07/26/11

Implementation Guidance documents are created to explain best practices for problem-solving or basic lab activities, typically but not always in response to questions submitted for interpretations which cannot be addressed adequately by that route. New IG documents are added over time, as topics for them are identified. Individuals that have questions about the applicability, scope, and use of this guidance may contact TNI at this link.

Implementation Guidance is available as a benefit to TNI Members only. You must be logged-in to view this content. If you are a TNI Member, click here to log in. For information about how to become a member, click here.


Module Subject Last Updated
Chemistry New Calibration Curve Overwritten with Old9-8-2019
Microbiology Chlorine Residual in Sample9-8-2019
Microbiology Membrane Filtration Method Blanks4-15-2021
Microbiology Microbiology Surrogate Recovery Failure4-17-2019
Microbiology Sample Receipt3-9-2015
Proficiency Testing Second PT Failure Means Loss of Certification for that Method9-8-2019
Quality Systems Conflict of Interest3-9-2015
Quality Systems Control of Records3-9-2015
Quality Systems Data Integrity Vulnerability4-17-2019
Quality Systems Extent of Analytical Records3-9-2015
Quality Systems Failure to Implement Corrective Action4-17-2019
Quality Systems Failure to Qualify Results4-17-2019
Quality Systems Improper Practice Report9-8-2019
Quality Systems Inadvertent Use of Expired Standard9-8-2019
Quality Systems LIMS Time Stamp Error9-8-2019
Quality Systems Manual Integration Misuse9-8-2019
Quality Systems Method Usage and Selection3-9-2015
Quality Systems New Scope but Old Methods Used9-8-2019
Quality Systems Required Frequency for Review of Data and Formal Reports3-9-2015
Quality Systems Results Do Not Match Historical Values9-8-2019
Quality Systems Sample Cooler Overlooked & Melted4-17-2019
Quality Systems Switched Samples4-17-2019
Quality Systems Tracing Support Equipment to Analytical Result9-8-2019
Quality Systems Use of Measurement Uncertainty3-9-2015
Quality Systems Vendor Recall4-17-2019
Quality Systems Wrong ID on Bench Sheet4-17-2019
Quality Systems & Chemistry Analytical Batch - Time Constraint3-9-2015
Quality Systems & Chemistry Improper Calibration Curve Change4-17-2019
Quality Systems & Chemistry Insufficient Sample Volume4-17-2019
Quality Systems & Chemistry Titrants - Documentation and Verification3-9-2015
Radiochemistry Matrix Spike Requirements3-9-2015
Toxicity Air Quality in the WET Lab4-17-2019
Toxicity Demonstration of Capability4-17-2019
Toxicity Randomization of Testing Chambers4-17-2019
Toxicity Reference Toxicant Tests Outside of Control Limits4-17-2019
Toxicity Scope of Results to be Plotted on Semi-log Graph4-17-2019
Toxicity Test Organism Criteria4-17-2019


Disclaimer: This material represents the opinion of its authors. It is intended solely as guidance and does not include any mandatory requirements except where such requirements are referenced. This guidance does not establish expectations of being implemented universally, exclusively, in whole, or in part.

This guidance does not establish or affect legal rights or obligations and is not finally determinative of the issues it addresses. It does not create any rights enforceable by any party in litigation with TNI, its accreditation bodies, or affiliated institutions. Any decisions made by TNI regarding requirements addressed in this guidance will be made by applying the applicable standards, policies or procedures to the relevant facts.

Individuals that have questions about the applicability, scope, and use of this guidance may contact TNI at this link.

Guidance Documents

TNI Guidance on Instrument Calibration

TNI V1M1 2016 Standard Update Guidance on Proficiency Testing Reporting Limit (PTRL)

TNI V1M4 2016 Standard Update Guidance on Detection and Quantitation (rev. 9-23-2019)