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Combined Interpretations of the 2003, 2009, and 2016 Standards that apply to Volume 1 of the 2016 TNI Standard

MODULE 4: CHEMISTRY TECHNICAL REQUIREMENTS



Section: 1.5.2        Limit of Detection and Limit of Quantitation


Question:  Our laboratory was recently cited with "The laboratory has not established procedures to relate LOD's with Limits of Quantitation (LOQ's) (EPA 200.8, 300.0, 6020, 9056)." I must be missing something here, or perhaps an expectation is being created by this standard, which is a favorite deficiency for auditors.  The LOD (which is not clearly defined in the NELAC standard) is interpreted by our company to be equivalent to the MDL.  The MDL is derived from an MDL study following the guidance in 40CFR136. The LOQ is interpreted by our company to be lowest concentration that can be reliably and accurately reported, and it is required that it be encompassed in the calibration curve.  Typically the low point of the calibration curve is equal to the LOQ when adjusted for sample preparation factors. In this context, the LOD and the LOQ are numbers that are derived independently, and the only requirement is that the LOD be equal to or less than the LOQ.  However, auditors are implying that there should be a fixed factor (or range, such as 1-10) separating the LOD and the LOQ.  In our laboratory, metals by ICP-MS have ratios of LOQ/LOD that range from 1.4 to 100.  In my 20+ years in environmental laboratories, I have seen LOQ/LOD ratios that are all over the place. Is the standard giving me permission to adjust MDLs upward, provided that they are supported by MDL studies, so that the LOD is within a fixed factor of the LOQ?  This would be convenient, because the LOD would not change from year to year.  Our clients would be very appreciative of invariable LODs.  The question is, is this something that NELAC supports? I would like to see some clarification on this standard, because the way it is written, it seems to create the perception that we are missing something.

TNI Response:  This clause was deleted in the 2009 standard.  The SIR is obsolete.

 

Question:  The standard allows a lab to forgo the MDL determination if they do not report outside the calibration range unless the method requires it. Since the determination of the MDL and the LDR are pointless exercises for labs that do not report outside their calibration range, I believe that the MUR of 3/12/07 allows a lab to delete these requirements from method requirements since it does not change the chemistry, it does not change the determinative step, and it does not change the performance of the method. Agree? Disagree?

TNI Response:  The Standard has been modified and this is no longer applicable. The 2009 standard allows laboratories to forego the LOD study if data are only reported to the LOQ.  The 2016 standard reversed this and all labs must now perform LOD studies.  Also, the 2012 Method Update Rule that added section 136.7 to 40 CFR also requires labs to perform MDL studies.

 

Question:  It is felt that the LOD validation procedure in the 2003 NELAC Standard is ambiguous and can result in two different interpretations. By using the relevant standards (C.3.1.b, D.1.2.1.a) as well as definitions in the glossary especially for terms such as a quality system matrix, you can construe two different procedures.  One interpretation is that the LOD must be determined only in the matrix of the sample. In other words, if a lab is analyzing wastewater effluent samples, the LOD must be validated only in a wastewater effluent matrix. Not only is this not practical but not possible for many analytes.
This is a challenge to the practical and second interpretation which allows for the LOD to be validated in a reagent water matrix.  As someone who is engaged in quality assurance work, whenever an alternative interpretation is brought to me, I must evaluate objectively all viewpoints and I feel there is merit to the alternative argument. With respect to the two choices, we like to hear from you as to which choice is right and as stated we like to alert you that they may be an ambiguity issue with the LOD procedure.

TNI Response:  C.3.1 b) only states that the LOD must be verified on each instrument used for reporting data. It doesn't place a limit on when that must happen. Therefore, if one of the replicates analyzed for the MDL determination meets the applicable criteria for LOD verification, that would meet the intent of the Standard. The value of the spike used to calculate the MDL must be at no more than 2-3x the calculated MDL. It is expected that all of the replicates in such a study would show a recovery to be used to calculate the MDL.  The language is virtually identical in the 2009 standard, but this section has been extensively revised in 2016.  The SIR will be obsolete when the 2016 standard is implemented.

 

Question:  The Standard states you must use the "established test method acceptance criteria" or "client data quality objectives for accuracy" when confirming the LOQ.  First of all, our clients virtually never set 'data quality objectives for accuracy', they rely on the lab to set that for the methods.  Second, only new methods set acceptance criteria at the LOQ.  What criteria should be used, for instance, for EPA 8000-series tests, which only designate an 85-115% CCV criteria at mid-level for most methods, but usually mandate no specific criteria for LCSs?  While using our lab generated LCS criteria may work, those numbers are usually developed using mid-level spiking levels.  Many new methods state CCVs must be within 60-140% at the LOQ, while LCSs may be within 50-150% of expected values.  Mid-level criteria are usually tighter.  Last, there's a problem with respect to the statement in TNI Standard (section 1.5.2.2), "The annual LOQ verification is not required if the LOD was determined or verified annually on that instrument."  I have seen several LOD/MDL studies that have good precision (produces a relatively low LOD), but the accuracy is terrible (average of 250% recovery).  In my opinion, being able to physically see something at extreme low levels doesn't mean you can accurately determine the concentrations at low levels.  Some range should be set like 50-150% at the LOQ for confirmation.

TNI Response:  It is up to the laboratory to determine these criteria if they are not specified in the method or by other rule or regulation. The language is virtually identical in the 2009 standard, but this section has been extensively revised in 2016.  The SIR will be obsolete when the 2016 standard is implemented.  Webcast training on LOD and LOQ is now available on the TNI website under the Educational Delivery System tab.

 

Question:  The description of the LOQ does not specify a requirement that the standard used for verification of the LOQ include all sample processing steps (like extractions and digestions). The language presented for the LOD verification clearly states that all sample processing steps must be included in the LOD verification process.  Should all sample processing steps be included in the analysis of the LOQ standard verification?

TNI Response:  C.3.2 states 'The laboratory shall determine the LOQ for each analyte of concern according to a defined, documented procedure. This implies that the procedure used for samples and LOQ is by the same defined, documented procedure.  The language is virtually identical in the 2009 standard, but this section has been extensively revised in 2016.  The SIR will be obsolete when the 2016 standard is implemented.

 

Question:  Are there parameters/analytes for which TNI does not require MDLs/LOD?  For example, residue(TSS, TDS, TS), BOD.....

TNI Response:  C.3.1 c) states in part 'An LOD study is not required for any component for which spiking solutions or quality control samples are not available such as temperature, or, when test results are not to be reported to the LOD (versus the limit of quantitation or working range of instrument calibration)...' The NELAC Standard doesn't require any LOD determinations unless data are reported below the LOQ, AND a spiking solution or quality control sample is available. The proposed revisions to the TNI standard provide additional clarity to this subject.  The language is virtually identical in the 2009 standard, but this section has been extensively revised in 2016.  The SIR will be obsolete when the 2016 standard is implemented.

 

Question:  Routine samples for TKN are analyzed daily with an automated distillation titration apparatus.  Typical results are 15 to 30 ppm based on a 100 mL digestion.  MDL studies of LFB samples @ 2.5 ppm yield results too little variation for valid LOD/LOQ values.  However, this lab never sees samples at this low in the range.  Do the sections cited above relieve the lab from performing any further MDL's?  Can the laboratory state it will not report any values lower than say 5 ppm or some other conservative value?

TNI Response:  C.3.1 c) states in part 'An LOD study is not required for any component for which spiking solutions or quality control samples are not available such as temperature, or, when test results are not to be reported to the LOD (versus the limit of quantitation or working range of instrument calibration)...' The NELAC Standard doesn't require any LOD determinations unless data are reported below the LOQ, AND a spiking solution or quality control sample is available. If the laboratory SOP or QA Manual states that this analysis is not reported below the LOQ, then an LOD is not required by the Standard. If more stringent standards or requirements are included in a mandated test method or by regulation, the laboratory shall demonstrate that such requirements are met.  The language is virtually identical in the 2009 standard, but this section has been extensively revised in 2016.  The SIR will be obsolete when the 2016 standard is implemented.

 

Question:  For our lab, MDL is the LOD. Once an acceptable LOD is established via MDL, if the spike used meets the LOD spike concentration criteria (2-3X the LOD of the single analyte), is it necessary to prep and analyze another sample, or can one of the replicates analyzed for the MDL determination itself can be considered as a verification of the LOD?

TNI Response:  C.3.1 b) only states that the LOD must be verified on each instrument used for reporting data. It doesn't place a limit on when that must happen. Therefore, if one of the replicates analyzed for the MDL determination meets the applicable criteria for LOD verification, that would meet the intent of the Standard. The value of the spike used to calculate the MDL must be at no more than 2-3x the calculated MDL. It is expected that all of the replicates in such a study would show a recovery to be used to calculate the MDL. The language is virtually identical in the 2009 standard, but this section has been extensively revised in 2016.  The SIR will be obsolete when the 2016 standard is implemented.

 

Question:  In reviewing an onsite report for metals analyses, the auditor noted that the lab did perform LOD analyses annually but that the LODs for vanadium and arsenic were lower than the blank analysis and that new LODs and LOQs must be reestablished.  I see nothing in D1.2.1.b that makes any comparison of an LOD to the blank results.  Does an LOD need to be higher than the blank?

TNI Response:  There is no requirement to compare the LOD with the blank. Theoretically, a blank should have no detectable contaminants. Any detection in a blank must be evaluated according to D.1.1.1d).  The language is virtually identical in the 2009 standard, but this section has been extensively revised in 2016.  The SIR will be obsolete when the 2016 standard is implemented.

 

Question:  Is it acceptable to demonstrate the accuracy and precision at the Limit of Quantitation (LOQ) using a concentration that is less than the LOQ, including down to ½ the LOQ?

TNI Response:  "The validity of the LOQ shall be confirmed by successful analysis of a QC sample containing the analytes of concern in each quality system matrix 1-2 times the claimed LOQ." The standard requires concentrations that are 1-2 times the claimed LOQ. A concentration below the LOQ may not have the same accuracy and precision and therefore could not be used to verify the LOQ. The language is virtually identical in the 2009 standard, but this section has been extensively revised in 2016.  However, this SIR may still be relevant.

 

Question:  Section 1.5.2.1 Limit of Detection (LOD) in its opening sentence states: "If the laboratory is not reporting a value below the Limit of Quantitation, a Limit of Detection study is not required."  Does this opening statement supersede, nullify, lessen and/or somehow impact on the requirements found in 1.5.2.1 d), e) and f)? To paraphrase, if you do not report a value below the Limit of Quantitation does a laboratory still have to initially determine the LOD, perform an LOD each time there is a change in the method or the instrument and/or verify the LOD annually.  There is a need for clarity the standard and obtain an standards interpretation of this section of the standard as it pertains to the above question.

TNI Response:  If the laboratory is not reporting a value below the Limit of Quantitation, a Limit of Detection study is not required, unless specified by the reference method. This statement supersedes any requirements that follow in Section 1.5.2.1.  The 2009 standard allows laboratories to forego the LOD study if data are only reported to the LOQ.  The 2016 standard reversed this and all labs must now perform LOD studies.  Also, the 2012 Method Update Rule that added section 136.7 to 40 CFR also requires labs to perform MDL studies.


Section: 1.5.2.1.2        MDL Requirements


Question:  40 CFR 136 Appendix B (3) (a) "During any quarter in which samples are being analyzed, prepare and analyze a minimum of two spiked samples on each instrument, in separate batches, using the same spiking concentration used in Section 2." If the variation in the spiking concentration is used to calculate the MDL (MDLS = t(n -1, 1-α = 0.99)Ss), and the lab uses the MDL to calculate a LOQ (maintaining that the LOQ ≥ the lowest calibration concentration), this may not be "a spike at or below the LOQ" as prescribed in TNI V1M4-2016 §1.5.2.1.2 because the concentration value does not play a role in calculating the MDL (DL). It seems the TNI ongoing verification definition differs from 40 CFR. If the lab were to use a concentration at or below the LOQ, this would not always satisfy 40 CFR 136 Appendix B (4) (b) "Include data generated within the last twenty four months, but only data with the same spiking level." The lab seeks clarification on when to verify at or below the LOQ and when to use the same spiking concentration as in the original study. Thank you.

TNI Response:  The TNI requirement does differ from the EPA MDL procedure in that it requires that the spikes used for the ongoing verification of the MDL be "at or below the LOQ." The EPA MDL procedure has no limitations for the spike concentration used in the initial determination and ongoing verification, other than they be at the same concentration. In order to comply, the LOQ would therefore be set at the concentration at or above the lowest calibration standard or the concentration of the spiked samples used to determine the MDL, whichever is greater. This will ensure that the spike concentration is at or below the LOQ and that the ongoing verification can be carried out using spikes of the same concentration as the initial determination, as is required by the TNI standard. Performing the EPA MDL procedure alone is not adequate to meet the requirements set forth in the TNI MDL standard. However, if you are required by the method to use the 40 CFR 136(b), then the EPA method must be used, per the first sentence of V1M4 §1.5.2.1.


Section: 1.6        Demonstration of Capability (DOC)


Question:  Currently our laboratory uses Work Groups for IDOC and DOC of the sample preparation methods (i.e., EPA 3005, EPA 3510, ... etc.) and the we perform IDOC and CDOC on individual analysts for the test methods (i.e., EPA 6020, EPA 8270, ... etc.).  This represents well our actual practice of having a formalized group of employees performing sample prep as a team effort, and then subsequent actual instrument analysis is performed by an individual. Because the 2009 Standard has been revised to no longer explicitly describe work groups, will it be required to DOC our prep group personnel individually under the 2009 Standard, or are these types of work groups still allowed to be DOCed as a formal team? As an alternative, under the 2009 Standard is it permissible to maintain DOC on the analyst as the individual responsible for the sample(s) for that test, with the prep team working under that DOCed analyst’s oversight?  This essentially wraps the sample prep and analysis together under a designated analyst who utilizes “assistant” individuals within the process. 

TNI Response:  Each individual analyst must have documentation on file that indicates that he/she is competent to perform the portion of the analysis for which he/she is responsible. Work cells may be used. The laboratory needs to define how the concept is used to demonstrate individual competence.

 

Question:  A laboratory in our program has requested clarification that the term "outside source" has the same or a different meaning from the term "secondary source."  The laboratory understands that a "secondary source" should be used for instrument calibration per NELAC 5.5.5.2.2.1.d but this is not required for demonstration of capability or determination of LOD or determination of LOQ.  The question is "Is 'outside source' the same as 'secondary source'?"  
TNI Response:  The term outside source is not equivalent to the term secondary source. The outside source cited in C.1 a) meant a source other than calibration standards. This is consistent with the definition of Quality Control Sample, which may be a Certified Reference Material, quality system matrix fortified by spiking, or actual samples fortified by spiking.  This language was deleted in the 2009 (and 2016) standards.  The SIR is obsolete.

 

Question:  I would like to have interpreted Appendix C – Demonstration of Capability C.1 paragraph 6.  and step a).  The test methods we are applying for NELAC accreditation are the EPA 500 methods for SDWA compliance testing.  These methods are mandatory test methods by both State and Federal regulation.  In paragraph 6 it states “following steps shall be performed if required by mandatory test method or regulation”. So my question is:  If a test method specifically has the IDCs to be completed by use of an LFB (not a QCS obtained from an outside source) then shouldn’t NELAC recognize these IDCs as acceptable for accreditation? I also interpret the language at a) that the QCS to be used for the DOC only needs be what we usually refer to as second source if the stock standards were prepared within the laboratory and not acquired through an outside source.

TNI Response:  The outside source cited in C.1 a) meant a source other than calibration standards. This is consistent with the definition of Quality Control Sample, which may be a Certified Reference Material, quality system matrix fortified by spiking, or actual samples fortified by spiking. If the laboratory's LFB meets the definition of a Quality Control Sample, the lab would be in compliance.  This language was deleted in the 2009 (and 2016) standards.  The SIR is obsolete.

 

Question:  We seem to have a difference of opinion in our lab. We have a manager that feels that the Table 2 of the EPA Method 548.1 give the criteria to be used for % Recovery for DOCs. They are stating that the Concentration used 100 shows a  95% recovery.  They are trying to change their acceptance to 95% +/- 20% Section 9.3 of the method states to use the R value from this table 2.   Aren't these only suggestions of R values? At the moment it is +/- 20% of the mean recovery

TNI Response:  Note: Laboratories should attempt to reconcile all differences in the interpretation of the standards and/or analytical methods with the applicable EPA Program, Regional Office and/or accreditation body. In reviewing Method 548.1, Revision 1.0, section 9.3 it is our interpretation, which concurred with one of EPA's Cincinnati's Chemist, that the laboratory's mean recovery +/-20% with an RSD of 30% is acceptable for the IDOC, then the laboratory may use the same values or tighter for DOCs in accordance with Chapter V, Appendix C. Table 2 of the method was developed only using 7 replicates, therefore it would be best for a laboratory to adhere to limits for accuracy and precision developed using their own mean recovery.  Nothing was changed in the 2009 or 2016 standards to suggest this SIR is still not relevant.

 

Question: Assessors require that each analyst perform an Initial Demonstration of Capability prior to running samples.  This IDOC is, as referenced in Appendix C, is 4 aliquots of a quality control sample.  5.5.4.2.2 states 'The laboratory shall confirm that it can properly operate all methods before introducing the environmental tests.  If the method changes, the confirmation shall be repeated.'  Since the definition of method does not include 'analyst', does the introduction of a new analyst mean the method has changed? 5.5.4.2.2 a) states (in part – I believe I have not left out any language germane to the question) ‘Prior to acceptance and institution of any method, satisfactory demonstration of method capability is required.  (See Appendix C and 5.5.2.6.b)’. 5.5.4.2.2. b) states ‘Thereafter, continuing demonstration of method performance, as per the quality control requirements in Appendix D (such as laboratory control samples) is required.’ 5.5.4.2.2 e) states ‘A demonstration of capability must be completed each time there is a change in instrument type, personnel, or method.’  Does the order in which these items are presented determine the requirements, such that a demonstration of capability is required prior to acceptance of any method, but thereafter laboratory control samples can be used to demonstrate an analyst’s (even a new analyst’s) capability?

TNI Response:  5.4.2.2.a and b refer to the institution of any method in the lab. Unless there is an analysis that does not require an analyst, the analyst is considered the lab for the purposes of DOC. 5.5.4.2.2.e requires a repeat of demonstration for each analyst or instrument type or method change. So if a new analyst is introduced, yes he/she must perform a DOC. No, the order in which items are presented does not determine the requirements.  This language was revised in the 2009 (and 2016) standards to focus on individuals.  The SIR is obsolete.

 

Question:  Is it necessary to perform continued proficiency for all 8 aroclors and toxaphene? Would it be acceptable to performed continued proficiency for only one pattern to meet this requirement?   

TNI Response:  For initial demonstrations of capability all analytes of interest would need to be analyzed: In this case all aroclors and Toxaphene. For the continuing demonstration of capability only the method required spiking analytes would be necessary.  Nothing was changed in the 2009 or 2016 standards to suggest this SIR is still not relevant. The requirement to analyze all analytes may be understood from the Standard language, however.

 

Question:  Section 5.5.4.2.2 states "Prior to acceptance and institution of any method, satisfactory demonstration of method capability is required. (See Appendix C and 5.5.2.6.b) In general, this demonstration does not test the performance of the method in real world samples, but in the applicable and available clean quality system matrix sample (a quality system matrix in which no target analytes or interferences are present at concentrations that impact the results of a specific test method), e.g., drinking water, solids, biological tissue and air."  The statement, "such samples shall be grouped according to their origin", confuses categorization.  If a lab seeks accreditation for biological tissue matrix, is a DOC required for shellfish, plant, fish tissue, etc.?  (Assuming the lab will be analyzing various types of biological tissue.)  Extending to batch QC, is the lab required to use a shellfish CRM for shellfish samples, a fish CRM for fish samples, etc.?

TNI Response:  When all real world materials contain target analytes and/or interferences, a "representative" matrix may be used for a given test method and analyst. If the test method as defined by the combination of preparation, cleanup and determinative methods for a given biological tissue is different from the test method (preparation, cleanup and determinative method) for another biological tissue, then separate DOCs are expected. With regard to batch QC, it is highly improbable that CRMs exist for all biological tissues that could be analyzed. However, when available a CRM that matches the tissue type (e.g., shellfish, fish, etc.) should be used. A representative material may be used for laboratory control spikes as long as the material used follows all steps of the test method.  Nothing was changed in the 2009 or 2016 standards to suggest this SIR is still not relevant. The IDOC process is based on the Quality System matrix, in this case 'biological tissue'.

 

Question:  A laboratory accredited by our program asserts that the form in NELAC Chapter 5 Appendix C.2 is needed only for documentation initial demonstrations of capability and not continuing demonstrations of capability.  It cites the language from NELAC 5.5.4.2.2.d "in all cases, the appropriate forms such as the Certification Statement" and from NELAC Chapter 5 Appendix C.1 "It is the responsibility of the laboratory to document that other approaches to DOC are adequate."  Other language in the same appendix prescribes the use of the form, for example  C.1 "All demonstrations shall be documented through the use of the form in this appendix" and C.2 "The following certification statement shall be used to document the completion of each demonstration of capability."  I am requesting an interpretation to resolve the question, is the Chapter 5 Appendix C Certification Statement required for documentation of continuing demonstrations of capability?

TNI Response:  C.2 of Appendix C states that "The following certification statement shall be used to document the completion of each demonstration of capability" This statement refers only to the demonstration of capability, not continuing demonstrations of capability. The laboratory may choose to use the form to document continuing demonstrations, but it is not required.  The form was eliminated in the 2009 standard.  Rather, the standard requires documentation. The SIR is obsolete.

 

Question:  A laboratory in our program states that it is using "marginal exceedences" as part of its evaluation criteria for determining initial demonstrations of capability.  The question is "Is the use of 'marginal exceedences' as described for evaluation of laboratory control samples also allowed for the evaluation of data associated with initial demonstrations of capability?

TNI Response:  The TNI Standard requires that all analytes meet the corresponding acceptance criteria for precision and accuracy stated in the method (if applicable) or in laboratory-generated acceptance criteria (if there is not a reference method with established mandatory criteria) for an Initial Demonstration of Capability (IDOC) prior to the analysis of actual samples. If any one of the analytes does not meet the acceptance criteria, the performance is unacceptable for that analyte.


Section: 1.7.1.1        Initial Calibration


Question:  ICVs have historically been treated as CCVs, in that high-biased failures and samples with no target compounds did not require reanalysis. It has been noted in a previous audit that this is not acceptable even though there would be qualifications on the final client report. Why would this practice not be acceptable?

TNI Response:  If the Initial Calibration Verification (ICV) does not pass the established acceptance criteria for the calibration technique used, the calibration curve is not valid and corrective actions must be documented and samples reanalyzed. An ICV is not is not the same as a Continued Calibration Verification (CCV) and should not be evaluated against the CCV acceptance criteria.

 

Question:  What input variables (analyte lot, solvent lot, balance, operator, etc.) must change in order for a second lot of standard to be considered to be prepared independently?

TNI Response:  5.5.5.2.2.1 d states that a standard obtained from a second lot may be used if the lot can be demonstrated from the manufacturer as prepared independently from other lots. In our mind, this is analogous to a preparation batch being prepared with the same process, personnel and reagents during a set timeframe. Assuming the manufacturer prepares a specific quantity of standard and declares that quantity a "lot", another lot prepared at another time would be independent of the first. The laboratory would be expected to contact the manufacturer to verify that one lot is not the same as another.  The 2003 and 2009 standards have identical language.  This section was slightly reworded in 2016 and a definition of "lot" was added to V1M2: Lot: A definite amount of material produced during a single manufacturing cycle, and intended to have uniform character and quality.  The SIR still has some relevance in further explaining this issue.

 

Question:  Does the requirement for second source standard include calibration curves for surrogate compounds?

TNI Response:  Surrogates are intended to provide a measure of recovery for every sample matrix (D.1.1.3.3 a). A second source check is designed to assure that the analytes of concern are being correctly identified and quantified. Since surrogates are not analytes of concern, and may be held at a constant level in a calibration curve, they are not required to be verified by a second source.  The 2003 and 2009 standards have identical language.  This section was slightly reworded in 2016 and a definition of "lot" was added to V1M2: Lot: A definite amount of material produced during a single manufacturing cycle, and intended to have uniform character and quality.  The SIR still has some relevance in further explaining this issue.

 

Question:  We have been informed that Environmental lab auditors are now requiring labs to use a second vendor for their second source calibration standards even when use of a second manufactured lot from the same vendor is allowed by both the 2003 NELAC and 2009 TNI standards.   We have even heard that second source from a second manufacturer raw material prepared by the same vendor is being noted as non-compliant in some instances.  What is the interpretation of what this standard requires of labs where it applies to non-DoD programs with regard to the following options:
1. Same vendor/supplier - two independently prepared lots from the same raw material.
2. Same vendor/supplier - two independently prepared lots from different manufacturer raw materials when available.
3. Two different vendor/suppliers for each of the primary and secondary lot standards.

TNI Response:  The purpose is to verify that the standards used for calibration have been properly prepared. The verification standard must be prepared independently from the calibration standard(s). The best option is standards from two different vendors; alternatively, standards from the same vendor but different lot numbers. While the original source (manufacturer) of the neat standard is important, the standard stresses independent preparation.  The 2003 and 2009 standards have identical language.  This section was slightly reworded in 2016 and a definition of "lot" was added to V1M2: Lot: A definite amount of material produced during a single manufacturing cycle, and intended to have uniform character and quality.  The SIR still has some relevance in further explaining this issue.

 

Question:  k) The laboratory shall use and document a measure of relative error in the calibration. i, ii-a and ii-b discuss running calculations on the calibration standard results used in the curve. For metals analysis, we use ICP/ICPMS and a zero point and single calibration standard, which makes it impossible to calculate %RE or %RSE of a mid point and low level calibration standard. We are interpreting the standard to read that when a zero point, single calibration standard is used, the requirements of 1.7.1.1.k do not apply and are replaced by the requirements in the next paragraph - section 1.7.1.1.L (which specifically discuss requirements for single point calibrations.) Please confirm that we are interpreting these requirements correctly.

TNI Response:  Your interpretation is confirmed as correct.


Section: 1.7.1.2        Continuing Calibration Verification (CCV)


Question:  Section 5.5.5.10 begins with the statement “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 continuing instrument calibration verification with each analytical batch. The following items are essential elements of continuing instrument calibration verification:”. This is a forward looking statement meaning that the pass/fail status of the CCV standard being run is evaluated only in light of it’s impact on the samples which follow the CCV standard.  Section 5.5.5.10 e) reads “If the continuing instrument calibration verification results obtained are outside established acceptance criteria, corrective actions must be performed. If routine corrective action procedures fail to produce a second consecutive (immediate) calibration verification within acceptance criteria, then either the laboratory has to demonstrate acceptable performance after corrective action with two consecutive calibration verifications, or a new initial instrument calibration must be performed.” The corrective action language in the standard only address what is necessary to proceed with analysis without recalibration. I referred to this evaluation as being “forward looking”. There is no interpretation given regarding any additional considerations, or limitation on corrective actions for nonconforming CCV events where they occur in the middle or the end of a sequence that requires acceptable bracketing CCVs such as in GC analysis without the use of internal standards.

TNI Response:  Running a second CCV in a sequence is not the intention of the standard. The practice of running two CCVs routinely would require that the laboratory evaluate each of them on every occasion. There must be a form of corrective action (i.e., instrument maintenance) prior to the second CCV being evaluated. Since no corrective action is being taken between the two CCVs, the laboratory is failing the requirement in 5.5.5.10 e of performing routine corrective action (unless it can be documented that something occurred in the first CCV, such as poor sample introduction, that did not occur in the second CCV), and cannot use the second CCV to alleviate the failing of the first.

 

Question:  “Calibration shall be verified for each compound, element, or other discrete chemical species, except for multi-component analytes such as Aroclors...”  A laboratory is saying that they do not need to run a Chlordane standard to report non-detect chlordane results because of this NELAC Quality Systems Chapter 5 statement.  They are saying that the auditors allow it.  No continuing calibration is required for SW-846 Method 8082?

TNI Response:  It is important to read the entire Standard, not just a single phrase. The full language of the referenced section is as follows: "Calibration shall be verified for each compound, element, or other discrete chemical species, except for multi-component analytes such as Aroclors, Total Petroleum Hydrocarbons, or Toxaphene where a representative chemical related substance or mixture can be used." The requirement is that a representative chemical related substance or mixture is to be used to verify the calibration. If a representative substance were used, such as alpha or gamma Chlordane in lieu of Technical Chlordane, that would meet the requirements of this section.


Section: 1.7.2        Quality Control (QC)


Question:  With regards to the requirement of spiking all targeted components over a 2-year period, is this an overall requirement per ANALYTE or per METHOD?  As an example, we analyze pesticides by EPA 525.2 and EPA 8270C.  Can we spike all target analytes for one method and cover the other?  Or must we spike all for both methods?

TNI Response:  The standard for multi-analytes tests requires that all targeted components be included in a spike mixture for evaluation during a 2-year period and includes any reported analyte (whether detected or not).The committee noted that the preparation for 525.2 and 8270C are different, and spike results could differ. Therefore, each method requires a separate spiking schedule. Methods 624 and 8260, which use the same preparation procedure, could use the same spiking study.

 

Question:  Under Matrix Duplicates it states that the precision may be expressed as RPD or another statistical treatment. We do not do matrix duplicates, we perform sample duplicates only and use percent recovery. Are we required to run matrix duplicates, or are we okay running sample duplicates only? If we are allowed to run sample duplicates only, do we have to express precision as RPD, or can we stick to percent recovery? If we need to switch to matrix duplicates do we need to use RPD or can we use percent recovery?

TNI Response:  Any laboratory-duplicated sample (however named, such as matrix duplicates, sample duplicates, or matrix spike duplicates) must be evaluated for precision. A percent recovery evaluates accuracy, but not precision. Precision must be evaluated by a statistical technique such as RPD, absolute difference or Percent relative standard deviation (% RSD).


Section: 1.7.3        Data Acceptance/Rejection Criteria


Question:  The composition of a method blank shall consist of a quality system matrix that is similar to the associated samples and known to be free of analytes of interest. No reference could be found in SW-846 Methods 5035, 8000, and/or 8260 that require a VOA method blank to contain a solid matrix.  In fact, in method 5035 section 8.2 it is stated before processing samples to analyze an organic-free water method blank....  Nothing about adding a solid matrix is mentioned. Adding a solid matrix to a VOA method blank would only potentially add contamination and not be reflective of the cleanliness of the analytical system.  Also if one adds a solid matrix (even if it does not contain analytes of interest) to a VOA method blank, should not the same solid matrix be added to all the samples as well? Basically, is it necessary to add a solid matrix to a VOA method blank when analyzing low level soil samples? Is it the intent of NELAC's definition of a method blank to override what is presented in the method?

TNI Response:  A blank is required to be free of the analytes of interest. Therefore, an appropriate blank for a solid matrix should not contribute contamination.  5.9.3 c) provides the following statements concerning the difference between 5035 and TNI: "The laboratory shall ensure that the essential standards outlined in Technical Modules or mandated methods or regulations (whichever are more stringent) are incorporated into their method manuals. When it is not apparent which is more stringent, the QC in the mandated method or regulations is to be followed."

 

Question:  There is inconsistency as to whether a data qualifying code must be applied to a sample result for which no target analyte was quantitated at or above the reporting limit, yet for which the same target analyte concentration in the method blank was at or above the reporting limit.  For instance, a laboratory measures a concentration of a target analyte in the method blank at or above the reporting limit.  However, upon evaluation of the nature of the contaminant and the effect on the analysis of each sample within the batch they determine there is no need or benefit to qualify sample results which were not above the reporting limit for the target analyte in question.  They determine, in this specific instance, the blank contamination does not affect the sample results.  At many laboratories and Accrediting Bodies the interpretation of the standard language is: if there is nothing reportable in the sample (e.g., no positive hits above the reporting limit) then there is no effect on the analysis and hence the blank contamination does not affect the sample results.  On the opposite end, an Accrediting Body has been observed to require laboratories to qualify all sample results (i.e., even those for which there were no reportable results) due to method blank contamination at or above the reporting limit.  Additionally, there has been observed inconsistency and a lack of a common understanding between both laboratories and Accrediting Bodies on the original intent of the above standard language.  That is, was it the intent of the standard authors for this language to apply in instances where the measured amount of a target analyte in both the method blank and sample is above the reporting limit and not to apply to sample results where the target analyte is not reportable (e.g., at or below the LOQ).  Please note, in this instance/example, it can be assumed a laboratory is fully complying with the standard in that they are investigating the source and cause of the contamination observed in the method blank, taking and documenting corrective action and reanalyzing and/or appropriately qualifying sample results at or above the reporting limit for a given method.  Please provide clarification on how the standard language is to be interpreted and applied by both laboratories and Accrediting Bodies in the above stated instance.

TNI Response:  Section 1.7.4.1 requires that ALL listed conditions be met before analytical results are qualified due to blank contamination. The laboratory must review the batch to determine the affect of blank contamination on each sample within the batch. The laboratory must reprocess or qualify the data if all the items described in a) through c) are met. The laboratory must document a corrective action if blank contamination is observed and evaluated.

 

Question:  The Standard states:  "The LCS shall be analyzed at a minimum of one (1) per preparation batch.  Exceptions would be for those analytes for which no spiking solutions are available, such as TSS, TDS, TVS, TS, pH, color, odor, temperature, dissolved oxygen or turbidity."  However, there are now spiking solutions available for some of these analytes such as TSS, TDS, TS, and many labs are using them.  The Standard has not been updated to reflect the availability of these solutions, and this exception has been in effect since at least the 2001 NELAC Standard.  Are labs now required by the Standard to analyze an LCS for TSS, TDS, and TS since spiking solutions are now available?  Is this section being changed in the 2015 Standard?

TNI Response:  A Laboratory Control sample is defined in the definitions as a sample matrix, free from the analytes of interest, spiked with verified known amounts of analytes or a material containing known and verified amounts of analytes and taken through all sample preparation and analytical steps of the procedure unless otherwise noted in a reference method. It is generally used to establish intra-laboratory or analyst specific precision and bias or to assess the performance of all or a portion of the measurement system.  Volume 1 Module 4 Section 1.7.3.2.2 of the standard states that "Exceptions would be for those analytes for which no spiking solutions are available.” If spiking solutions are now available then an LCS would be required per the standard. The quoted section of the standard is the exception. The examples listed are not an inclusive list and should be expected to change overtime therefore cannot be used as the exception but just as potential examples from the time in which the standard was written.  In addition Volume 1 Module 4 Section 1.7.3.2.3 of the standard states, "Alternatively, the LCS may consist of a media containing known and verified concentrations of analytes or as Certified Reference Material (CRM)."

 

Question:  Is it the intent of the standard that when evaluated by the same criteria, a passing MS replace the LCS in its totality or can an individual target compound failure in the LCS be replaced by an individual acceptable result in a matrix spike sample?

TNI Response:  The standards states as a note in 1.7.3.2.3 that "The matrix spike may be used in place of this control as long as the acceptance criteria are as stringent as for the LCS."  This statement in the standards does not allow a matrix spike to be used in place of a failing LCS either in its totality or for an individual target compound. A matrix spike may however be used in place of an LCS if an LCS is not analyzed as required and the LCS control limits are used to evaluate the MS. If a method has specific requirements for an LCS this note does not supersede those method requirements. The 2009 standard allowed an MS to be used in lieu of an LCS.  The 2016 standard reversed this. This SIR will be obsolete when the 2009 Standard is no longer in use.

 

Question:  A recent finding our laboratory got was "The laboratory does not include all target analytes in the matrix spike mixture over a 2-year period (EPA 8082)."  We feel that some auditing entities may be overreaching in their interpretation of this section.  Our response follows:

  • EPA 8082 describes the analysis of PCBs in environmental samples.  PCBs can be reported as Aroclors or as individual congeners; Our laboratory reports PCBs as Aroclors. Section 7.1.2 of the method states that "Aroclor 1016/1260 mixture may be an appropriate choice for spiking" because these two in combination represent all PCBs.  Section 8.4 of the method states that "If samples are not expected to contain target analytes, laboratories should use a matrix spike and matrix spike duplicate pair, spiked with the Aroclor 1016/1260 mixture." Furthermore, the NELAC standard states in Appendix D, section 1.1.2.1 (c), referring to PCBs, that "the spike should be chosen that represents the chemistries and elution patterns of the components to be reported." Aroclors are a special situation in that they are not a compound, but rather a formulation of different proportions of PCBs.

TNI Response:  The components to be spiked SHALL be as specified by the mandated test method. 8082 7.1.2 specifically states  “Such samples should contain or be spiked with the compounds of interest in order to determine the percent recovery and the limit of detection for that sample type (see Chapter One). When other materials are not available and spiked samples are used, they should be spiked with the analytes of interest, either specific Aroclors or PCB congeners. When the presence of specific Aroclors is not anticipated, the Aroclor 1016/1260 mixture may be an appropriate choice for spiking” and 8.4.1 states “Documenting the effect of the matrix should include the analysis of at least one matrix spike and one duplicate unspiked sample or one matrix spike/matrix spike duplicate pair. The decision on whether to prepare and analyze duplicate samples or a matrix spike/matrix spike duplicate must be based on a knowledge of the samples in the sample batch. If samples are not expected to contain target analytes, laboratories should use a matrix spike and matrix spike duplicate pair, spiked with the Aroclor 1016/1260 mixture. However, when specific Aroclors are known to be present or expected in samples, the specific Aroclors should be used for spiking. If samples are expected to contain target analytes, then laboratories may use one matrix spike and a duplicate analysis of an unspiked field sample.”  The method requires analytes that you may expect in samples. This would mean spike all analytes over a two year period and if you're doing projects of known contamination you have to spike with those the known contaminant. If they can demonstrate that they've never seen any PCBs in their laboratory, a case could be made that they could just use 1016/1260 as a spiking mixture. If that can't be demonstrated, then all Aroclors must be spiked over the course of 2 years.

 

Question:  Can control limits include 0?  Marginal exceedances must be random.  If control limits don’t include 0, poor performing analytes will consistently be marginal exceedances.

TNI Response:  The laboratory would have to demonstrate how its data can meet all other aspects of the method and still generate control limits that include a 0% recovery. However, there is no restriction on control limits using 0 - look at PT criteria for soil to see examples of this occurring.  As for marginal exceedances, there's no such thing as a "consistent marginal exceedance", since they are required to be random. Consistent means that there is something wrong in the process or the method just doesn't work for that analyte.