Non-Field PT Requirements

Municipal, Industrial, Commercial and Other Laboratories

Under the NC WW/GW LC Rule 15A NCAC 2H .0800, laboratories must demonstrate proficiency for all certified parameters (for which a proficiency testing sample is available) each year and the graded results must be received in this office by September 30. Proficiency Testing samples must be obtained from an accredited vendor as unknowns. If performance evaluation samples are not available for a parameter, certification for that parameter may be based on the proper use of the approved procedure as determined by an announced or unannounced on-site inspection.

North Carolina Permittees will not be required to order Discharge Monitoring Report-Quality Assurance (DMR-QA) Study PT samples (you can read more about the NC DMR-QA PT Study Exemption on the Field Lab PT Page) and, therefore, will not be responsible for reporting data for their contract laboratories any longer. 

PT Study Requirements

The following links describe proficiency testing requirements for commercial, municipal, industrial and other laboratories. A new Proficiency Testing Requirements document (see link below) serves as a guide to the PT sample requirements of the NC WW/GW LC program. In addition to clarifying the regulatory requirements for proficiency testing, this document answers many common questions concerning evaluation of PT sample results. Also included are important deadlines, penalties and corrective actions for proficiency testing sample failures. Highlighted changes, a condensed version of the proficiency testing requirements and an auditor's checklist may also be found in the links below.

Proficiency Testing Requirements Document (February 19, 2020, Revision 5.0) 

NC WW/GW LC memo describing 2019 PT Requirements  (January, 2019)

Highlighted Changes to PT Requirements for 2017 (May 31, 2017) [see above memo for additional changes]

List of Parameters and PTs Required for Non_Field Laboratories (June, 2020)

Proficiency Testing Checklist (May 12, 2017) 

Root Cause Analysis (RCA) and Corrective Action Report (CAR) Guidance (November, 2014)

NOTE:  At this time, we do not require PTs specific to each matrix. A single PT in either matrix shall suffice for demonstration of proficiency for that parameter method technology. A specific matrix PT is required only in cases where a method is matrix-specific (e.g., SW-846 9071B, SW-846 7471B, etc.).

Proficiency Testing Providers

The laboratory must obtain samples that are part of an official study obtained from a proficiency testing sample provider recognized by The NELAC Institute (TNI) and approved by the NC WW/GW LC program. A provider of PT samples must be accredited by a Proficiency Testing Provider Accreditor (PTPA) that meets the TNI requirements. A listing of organizations that are accredited to provide PT samples is available in the link below. Laboratories should check this list each time PT samples are ordered since the list changes periodically.

Link to current NC WW/GW LC and NELAC-approved Vendors of PT Samples

EPA Lab Codes

Since different accreditation programs use a wide array of laboratory identification systems, the PT providers need a singular means of identifying participant labs when grading and reporting PT results. This singular system of identification is your EPA Lab Code. Each certified laboratory must have an EPA Lab Code and this code must be documented on the results to the proficiency testing provider. Without this EPA Lab Code, the NC WW/GW LC program may be unable to credit the PT results to the correct laboratory. The EPA Lab Codes are assigned by the US EPA. The EPA contact for Lab Code assignment for PT studies is:

Mr. Jeffrey Wilmoth ( Phone: 706-355-8623

U.S. EPA Region 4
980 College Station Road
Athens, GA  30605-2720

Please include the following information with your request for a new EPA Lab Code:

Contact name:
Laboratory or Facility Name:
Physical Address (with zip code):
PO address (if different):
Lab/Facility phone number:
Fax number (if available):
Contact individual’s e-mail address:
Type of Study (WP, WS, DMR-QA):

EPA Lab Codes for Non-field Laboratories - updated May 2019

Chlorophyll a Round Robin Study

Currently, there are no performance evaluation samples for chlorophyll a that can be carried through an entire method from extraction to instrumental analysis.  Consequently, laboratories certified for chlorophyll a will be required to participate in a round robin with other government, academic, and commercial laboratories pursuant to North Carolina Administrative Code 15A NCAC 2H .0805 (c) (3). The round robin studies are designed to provide a measure of laboratory performance in the absence of vendor-supported proficiency testing. The reports provide an illustration of intra-laboratory and inter-laboratory precision as well as a best estimate of the central tendency of data reported by laboratories currently engaged in chlorophyll a testing. A copy of the Chlorophyll a Round Robin Study Standard Operating Procedure (SOP) can be viewed here.

The Division of Water Resources, Water Sciences Section began the annual chlorophyll a round robin in August 2007. Participating laboratories are asked to anlyze 6 to 10 samples, collected and split by Water Sciences Section staff according to their Standard Operating Procedure. The laboratories are also asked to complete a questionnaire concerning the analysis and their procedues. The Laboratory Certification Branch evaluates the study results and provides assistance to laboratories where needed. Participant laboratory results are not identified in the reports to ensure the reports are not used for unfair market advantage. Contact the Laboratory Certification Branch at (919) 733-3908 if you have any questions about a report.

Chlorophyll a round robin study reports
2007 2011 2015 2019
2008 2012 2016 2020
2009 2013 2017 2021
2010 2014 2018 2022

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