March 19, 2014

Adrian Hanley

USEPA Office of Water

1301 Constitution Ave NW

Washington, DC 20004

Dear Adrian:

The NELAC Institute is providing the attached proposed revision to the Method Detection Limit (MDL) 

procedure published in 40 CFR Part 136 Appendix B. TNI is requesting the Agency replace the current 

procedure with this one. Our stakeholder community of laboratories, state agencies, regulated industry 

and scientists believe this revision represents a significant improvement over the current MDL procedure. 

This new procedure is vitally important to the laboratory community in general and to the regulated 

NPDES dischargers they serve. We would specifically request this change be made in the next Method 

Update Rule.

The concept of an MDL, first developed by the Agency in 1979, is critical to ensuring the regulated 

industry provide reliable monitoring data. Laboratories need a reliable procedure that they believe will 

provide confidence in both their qualitative identifications as well as statements that reflect a non-detect 

and we believe this procedure achieves that goal. Replacing the current procedure with this revised 

procedure will benefit TNI’s 800 plus members as well as the public as a whole.

By way of background on the process, in 2011, TNI entered into a cooperative agreement with the 

Agency to develop measurement tools and accreditation standards. As part of this effort, TNI formed a 

new expert committee to “develop consensus standards that will establish requirements for fundamental

measurement practices such as Limit of Detection (LOD), Limit of Quantitation (LOQ), and instrument 

calibration to reduce quality system vulnerabilities.” To date, that effort has resulted in proposed revisions 

to the instrument calibration requirements in TNI’s accreditation standards applicable to laboratories that 

perform chemical measurements. The next stage now in progress will be a working draft standard for 

LOD and LOQ.

TNI is accredited by the American National Standards Institute as a consensus standards organization, 

and TNI’s Chemistry Committee conforms to all requirements of OMB Circular A-119. A membership 

roster of the committee showing stakeholder representation is attached to this letter.

The committee believes the Method Detection Limit procedure in 40 CFR Part 136 is, and will continue 

to be, the most frequently used procedure for determining an LOD. As you know, several of the members 

of TNI’s committee also served on the Federal Advisory Committee on Detection and Quantitation

(FACDQ). Based on recommendations in the FACDQ final report, TNI’s Chemistry Committee initiated 

an effort to revise the language in Appendix B of Part 136 to establish a new procedure that addressed the 

shortcomings of the current MDL procedure.

PO Box 2439, Weatherford, TX 76086  817-598-1624

www.nelac-institute.org
On August 22, 2013, TNI posted a draft version of a revised procedure on the TNI website with the 

opportunity for the public to provide comments. A copy of the proposed procedure was also provided to 

EPA’s Environmental Laboratory Advisory Board. The proposed procedure has been presented at 

national meetings such as the Environmental Measurement Symposium as well as many regional 

meetings such as the annual meeting of the Florida Society of Environmental Analysts. There has been 

overwhelming support for TNI’s efforts from the public.

TNI’s Chemistry Committee developed the proposed procedure using our consensus process. The 

committee believes this document represents the consensus opinion of all the stakeholders who 

participated in the effort. TNI is providing this document with no copyright restrictions as we believe this 

procedure is fundamental to the environmental monitoring community.

Please feel free to contact me if you have any questions.

Sincerely,

Jerry Parr

TNI Executive Director

CC: Jan Matuszko, EASB, Branch Chief 

Janet Goodwin, TSB, Branch Chief.

Lemuel Walker, EAD

Richard Burrows, TestAmerica, Inc.

Sharon Mertens, Milwaukee Metropolitan Sewerage District

PO Box 2439, Weatherford, TX 76086  817-598-1624

www.nelac-institute.org
Chemistry Expert Committee

The mission of this committee is to improve the technical quality of environmental testing 

methodologies by providing tools (e.g., detection, quantitation and calibration) that assure the quality 

of data, which may be adopted by federal and state regulatory agencies. 

Name Organization Stakeholder Group Sub-Group

Richard Burrows TestAmerica, Inc. Laboratory Commercial Laboratory

Francoise Chauvin New York City DEP Laboratory Municipal Laboratory

Dan Dickinson New York State DOH Accreditation Body NELAP Accreditation 

Body

Tim Fitzpatrick Florida DEP Laboratory State Laboratory

Nancy Grams Advanced Earth 

Technologies, Inc.

Other Consultant

John Phillips Ford Motor Co Other Regulated Industry

Gary Ward Oregon SPHL Accreditation Body NELAP Accreditation 

Body

Brooke Connor US Geological Survey Other Federal Agency

Mandi Edwards Envirochem 

Laboratories 

Laboratory Commercial Laboratory

Anand Mudambi US EPA Other Federal Agency

Scott Siders Illinois EPA Accreditation Body NELAP Accreditation 

Body

PO Box 2439, Weatherford, TX 76086  817-598-1624

www.nelac-institute.org