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Agricultural Marketing Service Room 2646-South Building Effective November 8, 2012

National Organic Program Washington, DC 20250 Page 1 of 4

File Name: NOP 2611 Laboratory Procedures for Residue Testing Rev03 09 13 2018 Authorized Distribution: Public

Instruction

Laboratory Selection Criteria for Pesticide Residue Testing

Links Update: September 13, 2018

1. Purpose

This document outlines the laboratory criteria recommended by the National Organic Program 

(NOP) for parties conducting pesticide residue analysis of organic agricultural products under the 

requirements at § 205.670 of the NOP regulations.

2. Scope

These procedures apply to certifying agents, State officials representing State organic programs, 

and representatives of the NOP who submit samples of organically produced agricultural 

products for pesticide residue testing.

3. Policy

Section § 205.670 of the NOP regulations specifies the conditions under which responsible 

parties should conduct testing of agricultural products that will be sold, labeled, or represented as 

“100 percent organic,” “organic,” or “made with organic (specified ingredients or food 

group(s)).” To meet this requirement, these parties are responsible for obtaining analyses of 

samples from organic agricultural products that are capable of detecting the presence of residues 

in violation of the NOP regulations as specified under § 205.105 or other applicable laws as 

provided for at § 205.670(e). To ensure consistency in the analytical approach and quality 

assurance of the data by parties conducting residue testing, the NOP is issuing the following 

instruction for the responsible parties to establish laboratory criteria as part of meeting the 

residue testing requirements under § 205.670 of the NOP regulations. Furthermore, under §

205.504(b)(6) certifiers must have procedures for sampling and residue testing to ensure that 

proper testing is routinely followed.

4. Procedures

4.1 Current Methods of Analysis

Analytical methods capable of determining multiple pesticide residues in a single analysis have 

been developed in recent years. The NOP recognizes that an international harmonized method 

for residue testing may not be possible at this time, but that sufficient policies and procedures 

must be in place to ensure that false positives and false negatives are not reported. To assess the 

incidence of pesticide residues remaining on foods, the NOP uses monitoring data compiled by 

USDA Agricultural Marketing Service (AMS), Science and Technology Program and U.S. state 

agricultural laboratories employing slight modifications to the QuEChERS method. The 

QuEChERS method has been readily accepted by many pesticide residue analysts and some 
United States Department of Agriculture 1400 Independence Avenue SW. NOP 2611

Agricultural Marketing Service Room 2646-South Building Effective November 8, 2012

National Organic Program Washington, DC 20250 Page 2 of 4

File Name: NOP 2611 Laboratory Procedures for Residue Testing Rev03 09 13 2018 Authorized Distribution: Public

modifications to the original method have been subsequently introduced to ensure efficient 

extraction of pH dependent compounds, to minimize degradation of susceptible compounds, 

expand the spectrum of matrices covered, and improve recoveries of pesticides not analyzed in 

the original reports.

The NOP recognizes that not all registered pesticides can be reliably determined using the 

QuEChERS method and that at this time no method exists which will analyze all registered 

pesticides efficiently. In collaboration with the USDA AMS Science and Technology Program, 

NOP created a “target” analyte list (NOP 2611-1) by examination of all 

pesticides/metabolites/environmental contaminants that have been detected in samples analyzed 

for the USDA Pesticide Data Program. Laboratories employed by certifying agents should 

attempt to analyze as many compounds on this list as possible. If certifying agents suspect a 

prohibited substance was used that is not included on the NOP “target” list, they should initiate 

sampling/testing and investigation.

4.2 Laboratory Selection Criteria

Certifying agents should consider the following when selecting a laboratory for residue analysis 

of their samples:

1. Laboratories should hold current accreditation to either:

o ISO/IEC 17025:2005, General Requirements for the Competence of Testing and 

Calibration Laboratories.

o An alternate standard approved by the NOP on a case-by-case basis. Certifying 

agents should contact their NOP Accreditation Manager for additional 

information.

A copy of the accreditation certificate should be provided to the certifying agent prior to 

shipping samples and should be attached to laboratory results when they are reported 

back to the certifying agent.

2. Laboratories should participate in an international proficiency test program. A 

proficiency testing program is the determination of the calibration or testing performance 

of a laboratory by means of inter-laboratory comparison. A copy of the proficiency test 

results from the most recent round of proficiency testing should be available from the 

laboratory together with any corrective actions taken if the laboratory has failed the 

proficiency test. Contact information for two international proficiency programs is

provided in the references below.

3. Laboratories should be capable of screening for the “target” analyte list of pesticides 

included on the document NOP 2611-1, analyzing the samples using gas chromatography 

(GC) and/or liquid chromatography coupled to a mass spectrometer (MS) or tandem mass 

spectrometers (MS/MS).
United States Department of Agriculture 1400 Independence Avenue SW. NOP 2611

Agricultural Marketing Service Room 2646-South Building Effective November 8, 2012

National Organic Program Washington, DC 20250 Page 3 of 4

File Name: NOP 2611 Laboratory Procedures for Residue Testing Rev03 09 13 2018 Authorized Distribution: Public

4. Laboratories should provide evidence that their analytical method is appropriate for the 

submitted sample and that suitable validation data are available. Correspondence should 

be available to the certifying agent documenting that the method meets the laboratories’ 

minimum internal quality assurance requirements.

5. Certifying agents should direct the laboratory to provide analytical results as follows:

If no residue is detected, then the result should be provided as not detected (ND). The 

limit of detection should be provided.

If some residue is detected below the limit of quantification (LOQ), then the result should 

be provided as “Trace” or “BQL” (below quantifiable level).

If residue is detected at or above the LOQ, then the result should be reported in parts per 

million (ppm). Parts per million (ppm) is equivalent to milligrams per kilogram (mg/kg).

4.3 Suggested Laboratory Practices

Laboratories should use a unique identifier to track the sample throughout the handling and 

analysis. Before homogenization, the sample may be stored at 4 degrees Celsius for up to 72 

hours, if fresh, or stored at ambient temperature in the case of samples normally stored at room 

temperature. If a sample was previously frozen and shipped on ice packs, then it should be 

homogenized upon receipt at the laboratory. The entire sample as received (up to 5 pounds (~2.5 

kg)) should be homogenized by the laboratory to obtain a suitable representative portion for 

analysis. Homogenized samples should be stored at less than -20 degrees Celsius. Violative 

sample homogenates should be retained (preferably stored at -80 degrees Celsius) until the 

contamination issue is resolved by the certifying agent.

Samples should not normally be washed or peeled (e.g. bananas, oranges). However, certain 

commodities may be hulled (e.g. hazelnuts, fresh soybeans), and/or pitted (e.g. mango, avocado) 

prior to homogenization. In some cases a sample will have to be reconstituted (frozen 

concentrated juices). It should be noted that U.S. EPA establishes tolerances on specific raw 

agricultural commodities (RACs) and feedstuffs derived from crops listed in Table 1 of the 

Residue Chemistry Guidance that may not apply to the submitted sample. For example,

tolerances on sweet corn are established from samples of sweet corn containing kernels and cob 

with the husk removed. A certifying agent submitting a sample of sweet corn for residue testing 

might chose to have the sample tested with the kernels, cob and husk and should direct the 

laboratory to do so. In those cases, sample results should indicate which part of the crop was 

tested.

5. References

Inspection and testing of agricultural product to be sold or labeled “organic”, 7 CFR, pt.205. 

Print.
United States Department of Agriculture 1400 Independence Avenue SW. NOP 2611

Agricultural Marketing Service Room 2646-South Building Effective November 8, 2012

National Organic Program Washington, DC 20250 Page 4 of 4

File Name: NOP 2611 Laboratory Procedures for Residue Testing Rev03 09 13 2018 Authorized Distribution: Public

Allowed and prohibited substances, methods, and ingredients in organic production and handling 

7 CFR pt.205. Print.

United States. Department of Agriculture. Agricultural Marketing Service. AMS Pesticide Data 

Program Standard Operating Procedures: SOP No: PDP QC. Revision 1. Washington, DC: 

United States Department of Agriculture, 2009. Print.

United States. Environmental Protection Agency. OCSPP Harmonized Test Guidelines Series 

860 - Residue Chemistry Test Guidelines. United States Environmental Protection Agency, Aug. 

1996. Web. 21 Dec. 2010.

"ISO/IEC 17025:2005 - General requirements for the competence of testing and calibration 

laboratories." ISO - International Organization for Standardization. 21 Dec. 2010.

AOAC INTERNATIONAL Homepage. 21 Dec. 2010 <http://www.aoac.org/>.

FAPAS Proficiency testing schemes - Quality assurance for laboratories worldwide. 21 Dec. 

2010 <http://www.fapas.com/>.

Quechers.com | home. 21 Dec. 2010 <http://www.quechers.com/>.

Approval

______________________________

Miles V. McEvoy

Deputy Administrator

National Organic Program