NR 149.442 Note
Links to 40 CFR Part 136
, 40 CFR Part 141
, NR 219, and SW-846 can be found on the Wisconsin department of natural resources laboratory accreditation program website.
The laboratory shall measure and document the sample temperature at the time of receipt when temperature preservation is required.
The laboratory shall consider any sample requiring preservation at ≤
6 ºC to be preserved if the sample is received at a temperature greater than its freezing point to 6 ºC. When samples are received on the same day that they were collected, the samples may not yet have reached the appropriate temperature by the time they arrived at the laboratory. These samples may be considered acceptable, without the need to qualify the data, if all the following apply:
Samples were received at the laboratory on ice. “Blue ice” packs may not be considered as received on ice.
When sample temperature measurements are required, the laboratory shall record any of the following:
The laboratory shall verify the pH of each bottle received for samples requiring chemical preservation to a specific pH requirement under this section. Bottles not received at the proper pH may be adjusted at the laboratory provided that the methods allow preservation upon receipt and the lab retains documentation of its actions.
NR 149.442 Note
pH verification is only required from the bottle that is analyzed.
Sample receipt documentation.
The laboratory shall document the receipt and condition of all samples in chronological hard copy or electronic records. The records may be maintained in any format that retains all the following information:
The identity of the client or entity submitting samples, or the project associated with the received samples.
The times of sample collection for samples to be analyzed for tests with holding times expressed in hours.
The unique sample identification code assigned by the laboratory.
Documentation of sample preservation status and other sample conditions on receipt for all sample containers analyzed for those tests for which it is appropriate.
An unequivocal link between the sample identification code assigned by the laboratory and the field collection identification code assigned by the collector.
The requested analyses, unless the laboratory collects and analyzes its own samples and analyses are directed by permit.
The reference to requested test methods when the collector or sample originator specifies the methods.
Any comments resulting from the inspection undertaken to determine whether samples meet the policy in sub. (2)
The laboratory shall have procedures and appropriate facilities for avoiding deterioration, contamination, loss, or damage of samples during storage.
The laboratory shall store samples requiring thermal preservations at ≤
C at temperatures from greater than the samples' freezing point to 6 o
The laboratory shall store samples separately from all standards, reagents, food, and other potentially contaminating sources. Samples shall be stored in areas that prevent or minimize cross-contamination.
The laboratory shall store sample extracts, digestates, leachates, or concentrates resulting from any initial preparatory step as specified in this subsection.
NR 149.442 History
History: CR 17-046: cr. Register February 2021 No. 782, eff. 6-29-21. NR 149.444
Initial instrument calibration requirements. NR 149.444(1)(a)(a)
The laboratory shall calibrate or verify the calibration of all analytical instruments before the instruments are used to provide any quantitative results.
Once a calibration model is selected, a calibration function is established, and an initial calibration is finalized, a laboratory may not change the model or calibration function after samples have been analyzed without performing another initial calibration.
The laboratory shall perform an initial calibration if any of the following apply:
A second consecutive (immediate) CCV standard is performed under the same conditions and it also fails and the corrective action taken does not result in two consecutive passing CCV standards.
The laboratory shall retain all the raw data necessary to reconstruct or reproduce calibration functions associated with initial calibrations.
For colorimetric technologies, the laboratory may not use a method blank to zero the instrument.
NR 149.444 Note
For colorimetric technologies other than those based on inverse chemistries, the instrument is to be zeroed with the matrix of interest which is generally reagent water.
The laboratory may not utilize pre-programmed initial calibrations, provided by the instrument manufacturer, for compliance testing.
The laboratory shall include or reference the details of initial instrument calibration procedures including algorithms, any required equations, and acceptance criteria in the method standard operating procedure.
When required by method, the laboratory shall process each calibration standard in the same manner as samples.
Point-to-point calibrations are not allowed unless otherwise specified in this chapter.
Minimum number of standards.
To establish calibration, the laboratory shall select the number of nonzero standard concentrations that is appropriate for the calibration model selected and the expected range of concentrations. If a method requires analyzing more than three standards to establish a linear calibration, and the laboratory chooses to narrow the calibration range of the determination to no more than two orders of magnitude, the laboratory may use 3 standards to generate the initial calibration. The minimum number of nonzero standard concentrations selected to establish calibration shall be three except for all the following:
Dissolved oxygen meters, for which the minimum shall be one. Dissolved oxygen meters shall be calibrated against water-saturated air or air-saturated water at a known temperature and pressure. Alternatively, calibration may be performed using an iodometric method.
Conductivity meters, for which the minimum shall be one. Conductivity meters shall be calibrated by verifying the cell constant or adjusting the meter based on the analysis of a potassium chloride standard solution.
Inductively coupled plasma emission spectrophotometers and inductively coupled plasma mass spectrometers, for which the minimum number shall be one.
Quadratic calibration models, for which the minimum shall be five.
Cubic calibration models, for which the minimum shall be seven.
Concentration levels of standards.
The concentration of the standards chosen to establish a calibration function shall be within the same orders of magnitude as the expected concentration of samples.
The laboratory shall select a calibration model that is appropriate for the expected behavior of the analytical instrument to be calibrated. To generate a calibration model, the laboratory shall select a reduction technique or algorithm that is appropriate for the calibration model and the number of nonzero standards used, subject to all the following:
The selected algorithm or reduction technique shall be describable mathematically and shall provide equations, coefficients, or parameters necessary to characterize the calibration function uniquely, unless an analytical instrument is tuned to conform to a universally accepted scientific law or scale.
NR 149.444 Note
The response of dissolved oxygen meters is generally adjusted to conform to the concentration of oxygen allowable in a given liquid at a specified temperature and pressure. The response of an ion selective electrode is generally tuned to conform to the Nernst equation. The response of a pH meter is tuned to conform to the universally accepted pH scale. When these instruments are adjusted or tuned according to these principles, characterizing the calibration reduction algorithm mathematically is not necessary.
Non-linear functions may not be used to compensate for instrument saturation, insensitivity, or malfunction.
The laboratory may use weighted algorithms, unless the weighted algorithms are chosen to compensate for deviations from the expected behavior of a detector of an analytical instrument resulting from saturation, insensitivity, or malfunction.
Except for methods that allow average response factors and average calibration factors, the laboratory may not use reiterative reduction techniques or algorithms that force calibration functions through zero.
NR 149.444 Note
Reiterative reduction techniques or algorithms that force the calibration function through zero obtain mathematically, by repeated application, a null response for a zero standard that has a nonzero response or adjust calibration parameters to obtain a theoretical null response without analysis of a calibration blank. This paragraph does not prohibit the use of average calibration or response factors or automatic zeroing as part of an initial calibration, when methods, regulations, or covered programs allow those techniques.
Excluding calibration points.
If one or more calibration standards are excluded from the calibration, all the following criteria shall be met:
Except for ICP, ICP/MS, and HRGC/MS, if the highest calibration standard is removed, the linear range shall be limited to the remaining high standard concentration.
Evaluating algorithm validity.
The laboratory shall establish acceptability criteria for initial calibrations. The type of criteria chosen, and the acceptance range shall be appropriate for the type of analytes to be quantitated, the calibration model selected, and reduction technique or algorithm chosen. Acceptability criteria shall be established using any of the following:
When the x-intercept is used to evaluate the calibration, then the value of the x-intercept of the calibration function for each analyte may not exceed its LOD.
Unless otherwise specified by the method, when RSE is used to evaluate the calibration, the relative standard deviation may not exceed 15% for inorganic analytes or 20% for organic analytes.
Unless otherwise specified by the method, when residuals of each calibration standard are used to evaluate the calibration, the standard recovery for all but the lowest calibration point shall fall within 90% to 110% for inorganic analytes or within 70% to 130% for organic analytes. Recovery for the lowest calibration point shall be within 80% to 120% for inorganic analytes or 50% to 150% for organic analytes.
When average response factors are used to reduce calibration data, the relative standard deviation of the response factors may not exceed 20% unless the method allows a larger percentage.
When linear regression or least squares analysis is used to reduce calibration data, the correlation coefficient (r) of the resultant calibration shall be at least 0.995 for inorganic analytes or 0.99 for organic analytes.
When quadratic (2nd
order) or cubic (3rd
order) analysis is used to reduce calibration data, the coefficient of determination (r2
) of the resultant calibration shall be at least 0.995 for inorganic analytes or 0.99 for organic analytes.
(7) Verifying accuracy.
Except for calibrations generated using dissolved oxygen meters, pH meters, or conductivity meters, the laboratory shall verify all initial instrument calibrations after the calibrations are generated, but before the calibrations are used to quantitate any samples, with a second source standard, referred to as an ICV standard
. ICV standards shall be treated in the same manner as the standards analyzed for the initial calibration. Unless otherwise required by method, regulation, or covered program, the acceptance criteria for the ICV standard shall be all the following:
Obtaining concentrations within 10% of the theoretical concentrations of all reportable inorganic analytes.
Obtaining concentrations within 20% of the theoretical concentrations of all reportable organic analytes.
When methods require an ICB be analyzed after the initial calibration, the ICB shall be treated in the same manner as the initial calibration standards. The concentration of an analyte in an ICB may not exceed its LOD.
NR 149.444 History
History: CR 17-046: cr. Register February 2021 No. 782, eff. 6-29-21; correction in (2) (intro.) made under s. 35.17, Stats., Register February 2021 No. 782. NR 149.446
Continuing instrument calibration requirements. NR 149.446(1)(1)
When an initial instrument calibration is not performed on the day of analysis, the continuing validity of the initial calibration shall be verified prior to analyzing any batch quality control or environmental samples by the analysis of one or more CCV standards, subject to all the following:
Except for multi-peak analytes, CCV standards shall contain all analytes to be reported and may be prepared from the same standards used to generate the initial calibration. CCV standards are required for multi-peak analytes when the analytes are detected and reported in the samples.
CCV standards shall be treated the same as the standards used in the initial calibration. When the method requires that the standards be treated the same as samples, the CCV standards shall be performed with the associated batch so that the CCV standards and samples are all processed together.
Continuing calibration verification is not required for technologies when there are no initial calibrations established.
If an LCS also serves as a CCV standard, the acceptance criteria of the CCV standard shall be used.
Continuing calibration verification shall be performed at least once on each analysis day when an initial calibration is not performed and prior to sample analysis and batch quality control analysis.
Continuing calibration verification shall be performed after the consecutive analysis of each group of 20 environmental samples, if 20 or more samples constitute an analytical batch, unless otherwise required by method, regulation, or covered program.
Minimum number of standards and concentration levels. NR 149.446(3)(a)(a)
For linear and quadratic model calibration functions, the laboratory shall analyze at least a single CCV standard. The concentration of the standard shall be within the range established during the initial calibration.
NR 149.446 Note
Linear calibration models include electrometric technologies (pH and ion selective electrode), average response factor, average calibration factor, linear regression, and least squares analysis.
For cubic model calibration functions or third order polynomials, the laboratory shall analyze at least two CCV standards in each instance when a single CCV standard is required by method, regulation, or covered program.