The Minnesota Department of Agriculture (MDA) requires that a current Quality Assurance/Quality Control (QA/QC) plan from a proposed commercial laboratory as well as specific analytical methods be pre-approved by the MDA for most agricultural chemical investigations. A QA/QC plan and analytical methods which were approved by the MDA and/or updated within the last two years are generally acceptable for fulfilling this requirement. Refer to Section D of this document for information required to be submitted or reported to the MDA. Please be aware that all laboratory data submitted to the MDA are subject to the reporting requirements listed below in item D.8.

A. Pesticides

The MDA maintains standard analytical lists for pesticides commonly required for agricultural chemical investigations in Guidance Document 26 Analytical Lists for Pesticide Incident Investigations. The MDA does not require specific methods for these analyses, therefore the proposed analytical methods also must be pre-approved. The minimum acceptable reporting limit will vary from compound to compound. Specific reporting limits for MDA standard list compounds in soil and water are attached to this document. The MDA laboratory staff will be available to discuss proposed analytical methods.

B. Nutrients – Nitrate/Nitrite-Nitrogen, Total Kjeldahl Nitrogen, Ammonia/Ammonium-Nitrogen

Nitrogen analyses required on agricultural chemical investigations for the compounds listed in Attachment 1 must have MDA approval for water and soil matrices. The laboratory will follow the requirements listed in Part D. of this document. Specific reporting requirements for MDA Standard list compounds are included in Attachment 1.

As a service to the public, the MDA will maintain and distribute a list of commercial laboratories (GD23 Pre-approved Commercial Laboratories: Fixed Base and Mobile) with MDA pre-approved QA/QC plans and analytical methods for standard MDA list compounds. All information provided to the MDA will be public information unless clearly marked as a trade secret under Minn. Statutes, Section 13.37, Subd. 1(b).

C. Additional Compounds

Additional compounds that could be requested on a site, including but not limited to arsenic, pentachlorophenol, polynuclear aromatic hydrocarbons (PAHs) and dioxins require the laboratory have ISO/IEC 17025:2005, National Environmental Laboratory Accreditation Program (NELAP), or Minnesota Department of Health Laboratory Accreditation.  The laboratory will provide the current scope list and certificate for the accrediting authority to MDA.

With the exception of MDA List pesticides and nutrients described above, the accreditation must be for the same compounds of interest at the site. There may be some exceptions to this requirement that will be handled on a case by case basis. Again, the MDA does not require specific methods for these analyses, therefore proposed analytical methods for non-accredited compounds also must be pre-approved.

D. Commercial Laboratories

Commercial laboratories performing work for agricultural chemical investigations involving MDA pesticides and nutrient analyses must provide the information described below to the MDA prior to doing work on a site.

  1. Quality Assurance Manual
  2. Organizational Chart
  3. Primary contacts including the project manager and QA manager/officer. Please provide names, phone numbers and email addresses.
  4. Analytical Methods: The laboratory will provide the written methodologies employed by the lab. The minimum reporting limits that must be met on standard analytical list compounds are found in Tables 1, 2 and 3 of Attachment 1.
  5. Method Detection Limit Studies: A method detection limit (MDL) study is required with each method and matrix submitted for approval. 40 CFR Part 136, Appendix B protocols will be followed.  Include the initial MDL determination, and ongoing annual verification with the yearly submission.  Include individual results with analysis dates, along with statistics used in the MDL calculation.
  6. Proficiency Testing: The laboratory will participate in a proficiency testing (PT) program that includes the compounds listed in Attachment 1 at a minimum of once per year. Please refer to the A2LA website for approved providers ( The PT results must be submitted to the MDA on an annual basis. Compounds that fall outside the performance limits will require corrective action. Corrective actions will be forwarded to the MDA.
  7. Quality Control Requirements: Laboratories participating in the MDA Pesticide Approval Program need to meet the QC outlined in Guidance Document 29-Laboratory Quality Control and Data Policy Guidance (GD29) Laboratories will not be required to fill out or submit the attachment that is included with GD29.
  8. Reporting requirements for results submitted to the MDA:  Please note that this information should be submitted for all compounds analyzed by the laboratory. 
  • Date of collection
  • Date of extraction
  • Date of analysis
  • Results of analysis
  • Internal Standards and Surrogate Recoveries as appropriate
  • Method detection and reporting limits
  • Assessment of data; include definitions of flags used in reporting
  • Results of field quality control samples
  • Results of quality control recoveries (spike recoveries, duplicate expressed as relative percent difference (RPD) or RSD
  • Narrative to describe any problems with analyses. This includes but is not limited to homogeneity of samples received, raising reporting limits, matrix interferences (e.g., discussion as to issues with matrix spike or the decision to analyze the sample in duplicate or triplicate and forgo matrix spike because of high levels in sample) and other issues with analysis.
  • Other information required by order, permit, etc.

Please direct any general questions or correspondence to: Stuart Orlowski, Laboratory Coordinator, Pesticide and Fertilizer Management Division at (651) 201-6148.

Attachment 1

Reporting Limits (R.L.)

Table 1. MDA List 1 Pesticides

Compound CAS # Soil R.L. (mg/kg) Water R.L. (ug/L)
Acetochlor 34256-82-1 0.05 0.5
Alachlor 15972-60-8 0.05 0.5
Atrazine 1912-24-9 0.05 0.5
Chlorpyrifos 2921-88-2 0.05 0.5
Cyanazine 21725-46-2 0.05 0.2
Deethylatrazine 6190-65-4 0.05 0.5
Deisopropylatrazine 1007-28-9 0.05 0.5
Dimethenamid 876-68-8 0.05 0.5
EPTC 759-94-4 0.05 0.5
Ethalfluralin 55283-68-6 0.05 0.5
Fonofos 944-22-9 0.05 0.5
Metolachlor 51228-45-2 0.05 0.5
Metribuzin 21087-64-9 0.05 0.5
Pendimethalin 40318-45-4 0.05 0.5
Phorate 298-02-2 0.05 0.3
Propachlor 1918-16-7 0.05 0.5
Prometon 1610-18-0 0.05 0.5
Propazine 139-40-2 0.05 0.5
Simazine 122-34-9 0.05 0.5
Terbufos 13071-79-9 0.05 0.2
Triallate 2303-17-5 0.05 0.5
Trifluralin 1582-09-8 0.05 0.5


Table 2. MDA List 2 Pesticides

Compound CAS # Soil R.L. (mg/kg) Water R.L. (ug/L)
2,4,5-TP (Silvex) 93-72-1 0.1 0.5
2,4-D 94-75-7 0.1 0.5
2,4-DB 94-82-6 0.1 0.5
2,4,5-T 93-76-5 0.1 0.5
Bentazon 25057-89-0 0.1 0.5
Dicamba 1918-00-9 0.1 0.5
MCPA 94-74-6 0.1 0.3
Picloram 1918-02-1 0.1 0.5
Triclopyr 55335-06-3 0.1 0.5


Table 3. MDA Nutrients

Compound   Soil R.L. (mg/kg) Water R.L. (mg/L)
Nitrate-Nitrogen NO3-N 10 NA
Nitrate/Nitrite-Nitrogen NO3/NO2-N NA 1.0
Total Kjeldahl Nitrogen TKN 150 1.0
Ammonia/Ammonium-Nitrogen NH3/NH4-N 20 0.02