Upcoming revisions to three wastewater methods reviewed at NEMC 2017

Monday morning, representatives from the EPA’s wastewater office reviewed the significant changes for the three major GC wastewater methods: 608.3, 624.1, and 625.1.

The overarching goals were to modernize the methods and bring the language and QC requirements in line with the methods from the drinking water and hazardous waste offices. The methods have been modified to include capillary columns, and the QC requirements have been updated to reflect this. Maximum calibration RSDs have been dropped to 20% from 35%, and they want to see full list QC spikes.

The most disappointing change is the requirement that the CCV be prepared from a 2nd source. The 500 and 8000 series methods have recently and explicitly moved away from this practice because a 2nd source doesn’t so much verify ICAL stability (precision) as it does accuracy. I’m including the relevant sections for 8270D Rev 5 below:

9.3.2 There must be an initial calibration of the GC/MS system as described in Sec. 11.3. In addition, the initial calibration curve should be verified immediately after performing the standard analyses using a second source standard (prepared using standards different from the calibration standards). The suggested acceptance limits for this initial calibration verification analysis are 70-130%. Alternative acceptance limits may be appropriate based on the desired project-specific DQOs. Quantitative sample analyses should not proceed for those analytes that fail the second source standard initial calibration verification. However, analyses may continue for those analytes that fail the criteria with an understanding these results could be used for screening purpose and would be considered estimated values.

11.4.3 The initial calibration (Sec. 11.3) for each compound of interest should be verified once every twelve hours prior to sample analysis, using the introduction technique and conditions used for samples. This is accomplished by analyzing a calibration standard (containing all the compounds for quantitation) at a concentration either near the midpoint concentration for the calibrating range of the GC/MS or near the action level for the project. The results must be compared against the most recent initial calibration curve and should meet the verification acceptance criteria provided in Secs. 11.4.5 through 11.4.7.

You’ll notice that the ICV acceptance criteria when using a 2nd source is 70-130%, while the daily (or 12 hour) CCV acceptance criteria is ± 20%. This is because the 2nd source brings additional uncertainty.

I’m making the revised methods available for anyone to review.

Method 608.3 – Organochlorine Pesticides and PCBs by GC/HSD

Method 624.1 – Purgeables by GC/MS

Method 625.1 – Base/Neutrals and Acids by GC/MS

3 Responses to “Upcoming revisions to three wastewater methods reviewed at NEMC 2017”

  1. James Ball says:

    I would agree that requiring a second source for the CCV is not a good idea. Sometimes I have to try multiple vendors before I can get a second source to agree with the primary source for all compounds, and then sometimes all but a few will agree and a third source is needed to get those outliers confirmed.

    Unless the vendors are using second sources from competing vendors to verify their standard mixes as in the method,(and that is included in their data packets) it will be difficult to be certain that all sources are equal.

    The EPA should really force the three branches (Drinking Water, Waster Water, and Office of Solid Waste) to harmonize their methods. I mentioned the term MS/MSD to someone from Drinking Water and they didn’t recognize the terminology until it was restated as LFSM/LFSMD, both acronyms are simply spiked sample matrix for QC. To me Matrix Spike makes more sense than Laboratory Fortified Sample Matrix.

  2. Travis Weaver says:

    That requirement is not a CCV, it is a one time verification of the initial calibration (ICV). This has been required in drinking water methods and NELAC for some time. I’m glad they state a wider limit, our auditors have required us to meet the CCV limits, even though there is increased uncertainty.

    Also note the methods you posted are not approved for the Clean Water Act, and have been modified (again) in the Method Update Rule from last year.

  3. James Ball says:

    In 624.1 the CCV is listed as being the same as the LCS which is defined in section 8.2.1

    8.2.1
    For the DOC, a QC check sample concentrate containing each analyte of interest (Section
    1.3) is prepared in methanol. The QC check sample concentrate must be prepared
    independently from those used for calibration, but may be from the same source as the
    second
    -source standard used for calibration verification/LCS (Sections 7.4 and 8.4). The
    concentrate should produce concentrations of the analytes of interest in water at the mid

    point of the calibration range, and may be at the same concentration as the LCS (Section
    8.4).

    The CCV requirements are listed in section 8.4

    8.4
    Calibration verification/laboratory control sample (LCS)
    – The working calibration curve or RF
    must be verified at t
    he beginning of each 12-hour shift by the measurement of an LCS.
    Note:
    The 12-hour shift begins after analysis of the blank that follows the LCS and ends 12 hours
    later. The blank is outside of the 12-hour shift. The MS and MSD are treated as samples
    and are analyzed within the 12-
    hour shift.
    8.4.1
    Prepare the LCS by adding QC check sample concentrate (Section 8.2.1) to reagent water.
    Include all analytes of interest (Section 1.3) in the LCS. The LCS may be the same sample
    prepared for the DOC
    (Section 8.2.1). The volume of reagent water must be the same as
    the volume used for the sample, blank (Section 8.5), and MS/MSD (Section 8.3). Also add
    an aliquot of the surrogate solution (Section 6.7) and internal standard solution (Section
    7.3.1.3).
    The concentration of the analytes in reagent water should be the same as the
    concentration in the DOC (Section 8.2.2).

    So according to this, the calibration for 624.1 must be checked every 12 hours (CCV) by using an LCS that is prepared from a source independent from the initial calibration source(Second Source).

    524 and 8260 define the CCV as being from the same source as the initial calibration which is more logical for ongoing checks.

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