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Procedures for Detection and Quantitation

Technical Workgroup

Federal Advisory Committee on Detection and Quantitation Approaches and Uses in Clean Water Act (CWA) Programs

Summary of Technical Work Group Conference Call #17
January 11, 2006
1:00 – 3:00 p.m. EDT

The next Technical Work Group call is scheduled for Wednesday, January 18, from 1:00 - 3:00 PM EST. The call-in number is 866-299-3188; access code is 2025661045#.

Future Meeting Dates

Subsequent Technical Work Group calls will resume on a biweekly basis, at 1:00 PM EST, as follows:

Action Items

The Technical Work Group agreed to the following action items during the 11 January 2006 conference call:

Bob Wheeler, Larry LaFleur and Jim Pletl will discuss, via telephone, ways to proceed with identifying what the federal advisory committee wants a detection and quantitation procedure to do. They will also discuss ways to effectively link Technical and Policy Work Group discussions.

The Single-Lab Subgroup will:

The Calibration Design Study Group (a.k.a. Multi/Inter-Lab Subgroup) will:

Ken Miller will begin filling in the revised matrix of procedures and characteristics as an effort toward normalizing the matrix. The draft matrix will be discussed at the February 1, 2006 Technical Work Group conference call.

Triangle will send the revised description of characteristics and reformatted matrix of procedures and characteristics to Technical Work Group members.

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Welcome and Introductions

At 1:00 PM Bob Wheeler, facilitator, welcomed participants to the call, conducted a roll call of Technical Work Group members and observers, and briefly reviewed the agenda for the meeting. He proposed adding a few items to the end of the agenda, or as additional topics to consider during discussion of the existing agenda. Those additional items were:

Mr. Wheeler asked for comments on two draft meeting summaries the group received via email: November 30 and December 14. Cliff Kirchmer requested a clarification on page 1 of the November 30 draft meeting summary regarding the issue of zero versus blank. He said that it was not that he did not understand the issue, rather he did not understand why this was an issue.

Mr. Kirchmer also commented on the December 14 notes saying that, with regard to the list of decisions made at the December federal advisory committee meeting, it was interesting to note that the reasoning behind the decision to drop consideration of blank correction was based on convenience rather than scientific evidence. John Phillips responded by saying that he was right in that the committee decided not to consider blank correction in analytical methods, but added that the discussion at the meeting was based more on practicality. Mr. Phillips said the federal advisory committee is interested in developing recommendations that EPA will implement. The method(s) the committee is looking at does not exclude blank correction; it does not require it. Requiring blank correction in analytical methods would require revisions to existing analytical methods.

The Technical Work Group agreed to adopt the November 30 summary, with revisions. They approved the December 14 summary, as written.

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Procedures and Characteristics Matrix

Bob Wheeler introduced the discussion topic saying that, although this was not a specific assignment from the committee, it has been suggested it could be a beneficial exercise for the Technical Work Group to complete and for the committee to have. Richard Reding, EPA, added that if understanding the difference among the procedures is prohibiting moving forward, it may be worthwhile to spend some time filling in and discussing the matrix in the time leading up to the March federal advisory committee meeting.

Mr. Wheeler said the goal would be to keep the priority assignments in mind, but ask one person to fill in the matrix and start discussions from that point. Technical Work Group members agreed that the issue with this exercise the first time it was done was that several individuals filled in the matrix based on their own interpretation of what was meant by each of the characteristics and their own understanding of the procedure. Since then, the characteristics have been revised to minimize any confusion on intent. Having one person begin to fill in the matrix would go a long way toward normalizing the answers within. Mr. Wheeler said there were two questions before the Technical Work Group:

  1. Should the group take on the additional task of normalizing the matrix, keeping in mind the priority assignments from the federal advisory committee?
  2. If so, should the person to fill it in be from the Technical Work Group or an EPA contractor?

The group agreed that it could be very beneficial to have the matrix complete in time for the March committee meeting, and agreed that the best option for impartiality would be an EPA contractor. Further, the group agreed that Ken Miller, EPA contractor, would complete the matrix for discussion at the February 1 Technical Work Group meeting. Mr. Miller will make note of his assumptions, comments and questions, and forward that with the completed matrix.

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Policy Workgroup Update

Mr. Wheeler asked Larry LaFleur to update the group on the discussions occurring within the Policy Work Group. Mr. LaFleur explained that the main focus within the Policy Work Group at this point is measurement/data quality objectives (MQOs/DQOs). Discussions of MQOs/DQO's in relation to the pilot test resulted in two questions of the Technical Work Group:

  1. Is it possible to have a range of MQOs (e.g. precision = 10-30% RSD)?
  2. Could the group explore the impact of different MQOs on a procedure?

Richard Reding said that he had the opportunity to discuss this with Mary Smith at EPA. With respect to uses, the issue of MQOs has to do with how they are used in EPA programs. Mr. Reding explained that the process of method development is different from the process of analytical evaluation with regard to MQOs. Typically, in method development guidance, MQOs are set in the beginning. Later in the process, certain benchmarks may be set to measure the routine performance of the method. Mr. Reding asked the group, if MQOs were set before commencing the pilot, whether there would be one set of MQOs for all pollutants.

Mr. LaFluer responded by saying this question gets to the heart of one of the issues of the federal advisory committee. Mr. LaFleur mentioned that the committee could set MQOs based on the minimum quality of data required to determine regulatory compliance (prescriptive approach) or it could set them on a sliding scale of MQOs based on how good an analytical method performs. John Phillips responded to Mr. Reding's question by saying that the multi-lab pilot study would be able to deal with multiple MQOs, but the single-lab pilot study would need to know the required objectives.

After substantial discussion on the topic, the Technical Work Group members agreed to:

  1. Provide input to the Policy Work Group on MQOs. Jim Pletl and Larry LaFleur will work with Bob Wheeler to strategize on specific recommendations and requests to forward to the Policy Work Group.
  2. Both pilot study design subgroups will discuss the options for MQOs.

Jim Pletl added a final comment saying he understands the difficulty with setting numeric objectives. However, his feeling was that the federal advisory committee needed to more thoroughly discuss what it wanted out of procedures. While there may be differences based on uses and circumstances, he said it was important to seek committee consensus on what a procedure will do before deciding what the Technical Work Group wants to get out of the studies. This idea will be furthered via a discussion among Jim, Larry, and Bob Wheeler.

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Single-lab Subgroup Report

Bob Wheeler started the discussion by explaining, from his understanding, the two issues the Single-lab Subgroup is struggling with at the moment:

  1. The need for a better definition for what is meant by quantitation; and
  2. A definition for the critical level for censored methods.

Richard Burrows confirmed that was correct. The Subgroup has also been working with Ken Miller to collect and evaluate existing data to build an understanding of method performance over time. Mr. Burrows suggested it would be valuable to have the full Technical Work Group provide input on the latter, and said he would distribute via email a document identifying LC for various censored methods.

Mr. Wheeler asked what still needed to happen to evaluate LQ using existing data. Mr. Burrows responded that the Subgroup will need to obtain additional data from providers in a reasonable format. Mr. Burrows said his lab and some state labs could generate LCS data.

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Multi-lab Subgroup Report

Larry LaFleur said the Subgroup had held one conference call since the last Technical Work Group meeting and has various works in progress. The focus of their work has been on objectives and approaches to defining and designing multi-lab and inter-lab studies. The Subgroup is also looking at existing data to get a sense of how to design this study. Mr. LaFleur said that studies involving replicates with multiple spike levels (inter-lab) are really calibration studies. A multi-lab study is about using single-lab data across many labs, evaluating laboratory's LC, LD, and/or LQ, and then drawing conclusions based on criteria.

Mr. LaFleur said the former case will really be the emphasis of the Subgroup's study design. Therefore, he proposed changing the name of the Subgroup to be more reflective of its actual work. The Technical Work Group agreed to rename the Subgroup as the "Calibration Design Study Group," and requested that the name change be passed by the Policy Work Group.

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Public Comment

Tom Georgian of the US Army Corps of Engineers asked two questions:

  1. Is there intent to do LD for censored methods for the single labs? Mr. Burrows responded that the federal advisory committee already decided not to consider LD for the single-lab pilot study.
  2. 2. Does EPA intend to not do any statistical evaluation of the data near LC or LD, and if not, is that acceptable to EPA?

Mr. Georgian went on to say that values for LQ are much higher and errant than LC and LD. Using decision limits close to LQ is problematic; high censoring limits are very bad.

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Wrap-up and Closing

Mr. Wheeler summarized the action items from the discussion and thanked members for their hard work. He adjourned the meeting at 3:00 p.m. EST.

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Attendance

Technical Work Group Members

Triangle Associates: Derek Van Marter and Robert Wheeler

Observers

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