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TNI Standards Guidance

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.

 

Module: Chemistry


Subject: New Calibration Curve Overwritten with Old

Question 1

The weekend staff recalibrated an instrument on Saturday, and ran samples following the calibration curve. Week day staff came in on Monday, and loaded the prior calibration to process Friday's samples. They failed to reload the Saturday calibration curve back to the instrument, and all subsequent data for the next month was processed and reported with the old calibration curve.  How could this have been discovered? What course should the investigation take?  What should be done to correct the situation?

All samples affected by the mistaken curve should be investigated.  Involve weekend staff and weekday staff and supervisor in the root cause investigation and resolution process.

The 2016 TNI standard requires that the laboratory uses the most recent initial calibration generated for a given analysis.  In the event that a previous calibration is accidently used, it may still be possible to use the data.   Review and compare both calibration curves.  If the responses are essentially the same and all QC is still passing, make a note on the data to ensure traceability and defensibility.  If there is a significant difference in the responses, reprocess all affected data and issue an amended report to clients, including a narrative explaining what happened that warranted the amended report.

Data reviewers and analysts need more training to detect such errors. To make the calibration status clear, the following are examples of potential options:

  1. Calibration date (by method) can/should be posted directly on the outside of the instrument,
  2. Typically maintenance and calibration go hand in hand so it should/could be documented in the maintenance log, and
  3. Each laboratory should develop a process/procedure to clearly identify calibration status and ensure that the most recent calibration curve is being used.  The procedure should address exceptions and/or unique circumstances and the criteria used for approval. 
If time allows, it is recommended to perform an impact study.


References:

2009 & 2016 TNI

2009 TNI V1M2 and 2016 TNI Rev. 2.1 V1M2
4.0 Management Requirements, §4.1.5 a, f, g & h
4.2 Management §4.2.1 and §4.2.8.5
4.9 Control of Nonconforming Environmental Testing Work (ISO/IEC 17025:2005(E), Clause 4.9) §4.9.1 a thru e and §4.9.2
4.11 Corrective Action (ISO/IEC 17025:2005(E), Clause 4.11) §4.11.1 thru §4.11.5
4.13 Control of Records §4.13.2.1 and §4.13.3 a, f and i
5.2 Personnel (ISO/IEC 17025:2005, Clause 5.2) §5.2.1
5.9.3 Essential Quality Control Procedures §5.9.3 a
5.10 Reporting the Results §5.10.9

EL-V1M4 2009

1.7 Technical Requirements

1.7.1 Initial Calibration

1.7.1.1 Instrument Calibration

The following items are essential elements of initial instrument calibration:

a) the details of the initial instrument calibration procedures including calculations, integrations, acceptance criteria and associated statistics shall be included or referenced in the method SOP. When initial instrument calibration procedures are referenced in the method, then the referenced material shall be retained by the laboratory and be available for review;

b) sufficient raw data records shall be retained to permit reconstruction of the initial instrument calibration (e.g., calibration date, method, instrument, analysis date, each analyte name, analyst’s initials or signature; concentration and response, calibration curve or response factor; or unique equation or coefficient used to reduce instrument responses to concentration);

c)  sample results shall be quantitated from the initial instrument calibration and may not be quantitated from any continuing instrument calibration verification unless otherwise required by regulation, method, or program;

i)   if the initial instrument calibration results are outside established acceptance criteria, corrective actions shall be performed and all associated samples re-analyzed. If re-analysis of the samples is not possible, data associated with an unacceptable initial instrument calibration shall be reported with appropriate data qualifiers.

1.7.2 Continuing Calibration

When an initial instrument calibration is not performed on the day of analysis, the validity of the initial calibration shall be verified prior to sample analyses by a continuing instrument calibration verification with each analytical batch. The following items are essential elements of continuing instrument calibration verification.

a) The details of the continuing instrument calibration procedure, calculations and associated statistics shall be included or referenced in the method SOP.

d) Sufficient raw data records shall be retained to permit reconstruction of the continuing instrument calibration verification (e.g., method, instrument, analysis date, each analyte name, concentration and response, calibration curve or response factor, or unique equations or coefficients used to convert instrument responses into concentrations). Continuing calibration verification records shall explicitly connect the continuing verification data to the initial instrument calibration.

e) Criteria for the acceptance of a continuing instrument calibration verification shall be established. If the continuing instrument calibration verification results obtained are outside the established acceptance criteria and analysis of a second consecutive (immediate) calibration verification fails to produce results within acceptance criteria, corrective actions shall be performed. The laboratory shall demonstrate acceptable performance after corrective action with two consecutive calibration verifications, or a new initial instrument calibration shall be performed. If the laboratory has not verified calibration, sample analyses may not occur until the analytical system is calibrated or calibration verified. If samples are analyzed using a system on which the calibration has not yet been verified the results shall be flagged.

EL-V1M4-2017-Rev 2.2

1.7 Technical Requirements

1.7.1.1 Initial Calibration

Samples shall be associated with an acceptable initial calibration. If the initial calibration is not acceptable, corrective actions shall be performed and all associated samples re-analyzed. If reanalysis of the samples is not possible, data associated with an unacceptable initial calibration shall only be reported with appropriate data qualifiers. The following items are essential elements of initial calibration:

a) the details of the initial calibration procedures including calculations, integrations, acceptance criteria, and associated statistics shall be included or referenced in the method SOP. When initial calibration procedures are referenced in the test method, then the referenced material shall be retained by the laboratory and be available for review;

b) sufficient raw data records shall be retained to permit reconstruction of the initial calibration (e.g., calibration date, method, instrument, analysis date, each analyte name, and analyst’s initials or signature; concentration and response, calibration curve or response factor; or unique equation or coefficient used to reduce instrument responses to concentration);

c) the laboratory shall use the most recent initial calibration analyzed prior to the analytical batch, unless otherwise specified by the method.

1.7.1.2 Continuing Calibration Verification (CCV)
e) Sufficient raw data records shall be retained to permit reconstruction of the continuing instrument calibration verification (e.g., method, instrument, analysis date, each analyte name, concentration and response, calibration curve or response factor, or unique equations or coefficients used to convert instrument responses into concentrations). Continuing calibration verification records shall explicitly connect the continuing calibration verification data to the initial calibration.

i) sample results shall be quantitated from the initial calibration and may not be quantitated from any continuing calibration verification unless otherwise required by regulation, method, or program.