United States Department of Agriculture

Agricultural Marketing Service, Science & Technology

Pesticide Data Program

SOP No: PDP SAMP Page 1 of 29

Title: Sampling Procedures for PDP

Revision: 2 Replaces: 07/01/2018 Effective: 06/05/2023

1. Purpose:

To provide standardized procedures for all States participating in the USDA/AMS Pesticide Data 

Program (PDP) for the following:

⎯ development of quarterly sampling plans and sampling documentation.

⎯ sampling procedures.

⎯ packing and shipping procedures.

⎯ implementation of Sample Information Forms (SIFs) and Chain of Custody.

2. Scope:

This Standard Operating Procedure (SOP) shall be followed by all State personnel involved in the 

management and collection of samples for PDP.

3. Outline of Procedure:

5. SAMPLING PLANS AND DOCUMENTATION

5.1 Master Site List

5.2 Relative Volume Information for Sampling Sites

5.3 Quarterly Selection of Sampling Sites

5.4 Quarterly Sampling Schedules, Fact Sheets, Laboratory Mailing Addresses, and Shipping 

Assignment Charts

5.5 Assignment of Sample Collectors

6. SAMPLING PROCEDURES

6.1 Primary, Alternate, and Proxy Site Sampling

6.2 Sample Size

6.3 Sample Collection

6.4 Collection of Specific Commodities

6.5 Purchasing Samples

7. PACKING AND SHIPMENT OF SAMPLES

7.1 Packing Procedures for All Commodities

7.2 Packing Fresh and Delicate Commodities

7.3 Packing Processed Commodities

7.4 Shipment of PDP Samples

7.5 Shipping Fresh and Delicate Commodities

7.6 Shipping Processed Commodities

8. SAMPLE INFORMATION FORMS AND CHAIN OF CUSTODY

8.1 PDP General Requirements
United States Department of Agriculture

Agricultural Marketing Service, Science & Technology

Pesticide Data Program

SOP No: PDP SAMP Page 2 of 29

Title: Sampling Procedures for PDP

Revision: 2 Replaces: 07/01/2018 Effective: 06/05/2023

8.2 Electronic Sample Information Forms (eSIFs)

8.3 Paper Sample Information Forms

8.4 Chain of Custody

9. TRAINING AND EVALUATION OF SAMPLE COLLECTORS

9.1 Training for Sample Collectors

9.2 Evaluation of Sample Collectors

10. Special Sampling Scenarios

10.1 Makeup and Resample

10.2 Double or Triple Sampling

4. References:

• Duan, F., Gregg, M., Jacob, T., Keller, T., and Quan, P. 2016. Estimating the Precision of Quantile 

Estimates of Pesticide Residues. U.S. Department of Agriculture, National Agricultural Statistics 

Service, Methods Division, internal publication.

• PDP/MDP Federal/State Meeting, Denver, CO, September 27-29, 2005

• PDP Federal/State Meeting, Fairfax, Virginia, October 26-28, 2004

• Sampling Managers’ Meeting, Manassas, Virginia, June 18-19, 2002

• Federal-State Meeting, Seattle, Washington, October 30-November 1, 2002

• Memo; PDP Sampling and RDE Issues, November 16, 1999

• Federal-State Meeting, Alexandria, Virginia, October 26-28, 1999

• PDP/MDP Technical Meeting, Richmond, Virginia, March 27-31, 2006

• USDA Tropical Products Transport Handbook, September 1989

• USDA Agricultural Export Transportation Handbook, February 2004

• USDA, AMS, Protecting Perishable Foods During Transport by Truck September 1995; 

Reprinted July 2008.

• FedEx Guide to Proper Packaging

• FedEx Guide on Packaging Perishable Shipments

• User Guide for PDP Remote Data Entry (RDE) Electronic Sample Information Form (eSIF),

Version 5.0 September 2016

• SAMP APPE-1: A blank Sample Information Form (Revision 6, version effective October 1, 

2016) with accompanying instructions 

5. Sampling Plans and Documentation:

5.1 Master Site List

Each State participating in PDP sample collection shall be responsible for 
United States Department of Agriculture

Agricultural Marketing Service, Science & Technology

Pesticide Data Program

SOP No: PDP SAMP Page 3 of 29

Title: Sampling Procedures for PDP

Revision: 2 Replaces: 07/01/2018 Effective: 06/05/2023

documenting a master site list that includes all PDP sampling sites.

Sampling sites for PDP samples will be close to the point of consumption. The current 

sampling frame consists of wholesale food locations such as distribution centers and terminal 

markets. Retail sites should not be included on the master site list.

The master site list shall include the following information for each sampling site: 

• Site code

• Region or other geographical division (if applicable)

• Facility name and mailing address

• Date of inclusion or date of deletion from the site list, when known, clearly marked as 

such. Refer to Section 5.1.10 and 5.1.11 for requirements on the recording of new and 

inactive sites. 

• Type of facility (e.g., terminal market, chain store distribution center, wholesale market, 

etc.)

• Type(s) of commodities available at the sampling site (e.g., fresh/canned/frozen fruit and 

vegetables, etc.). This information will be used by MPD to code the sites in the PDP 

database.

• Relative volume information (Refer to Section 5.2 for method of calculation)

For all types of sampling facilities, States shall assign each site a unique numerical 

reference code per MPD instructions. At terminal market locations, each vendor will be assigned 

a unique site code. This site code will be included as part of the sample's permanent 

identification number. 

If site codes are assigned based on a particular organizational structure, rather than 

random numerical or alphabetical order, this numbering system shall be easily identifiable on 

the site list. For example, a State may divide its sites into geographical regions and assign the 

site codes accordingly (i.e., 100's for Region 1, 200's for Region 2, etc.).

Small, remote sampling sites that are too expensive or difficult to access to collect a 

sample should not be included on the State’s master site list. State internal SOPs shall explain 

the basic criteria used to determine which sampling sites to allow or exclude from the master 

site list. 

Site codes shall be assigned only once. If the physical location and facility remains the 

same (only the name changes), the site may retain the original site number. The old and new 

name should be shown on the master site list for referencing samples collected prior to the name 

change.

If the site name remains the same, but the physical location of the facility is moved to 
United States Department of Agriculture

Agricultural Marketing Service, Science & Technology

Pesticide Data Program

SOP No: PDP SAMP Page 4 of 29

Title: Sampling Procedures for PDP

Revision: 2 Replaces: 07/01/2018 Effective: 06/05/2023

a new address, a decision on the assignment of the original or a new site code will be made by 

the PDP Sampling Team in consultation with National Agricultural Statistics Service (NASS)

on a case-by-case basis.

If a site has been deleted from active sampling and is later reinstated, it must retain the 

same site number as before.

When locations are added to a master site list, each new location’s corresponding 

relative volume information shall also be provided. The revised master site list and relative

volume information shall be provided to NASS.

Inactive sites must remain on the master list but shall be denoted as no longer included 

in active sampling. Inactive sites may become “active” again later if appropriate. The site code 

and all other information pertaining to an inactive site shall remain on the master site list for 

future reference. 

Changes to the master site list shall be made as they occur. Information on site changes 

shall be provided to the PDP Sampling Team, PDP Database Administrator, and the NASS 

statistician. NASS must be aware that sites have been made inactive so that they are removed 

from the quarterly selection process. When new sites are added or previous sites are reinstated 

as active, the PDP Sampling Team, PDP Database Administrator, and the NASS statistician 

shall be notified as soon as possible because these sites should be included in the routine site 

selection process. If a State selects sites for sampling from its own Master Site List, notification 

of changes need only be reported to MPD as they occur.

MPD shall be responsible for updating the PDP database to reflect sampling site 

changes as they occur. MPD will send the State Sampling Manager an updated site look-up table 

for distribution to their sample collectors for import into their Remote Data Entry (RDE)

electronic sample information form (eSIF) application when new sites are added. Quarterly, 

MPD will send the laboratories an updated site look-up table holding all States/Sites for import 

into their local lab RDE tool.

Yearly, MPD shall provide State Sampling Managers with a copy of their State’s 

master site list from the PDP central database, which will include the codes for the sampling

sites, type of commodities sampled at each site (i.e., canned/frozen/fresh commodities), and 

relative size measures for each site (refer to Section 5.2). State Sampling Managers will be 

responsible for comparing the database site list with their records to detect any discrepancies 

and send revisions to the PDP Sampling Team. MPD will make corrections, as needed, to update 

the information in the PDP database and distribute site look-up table updates for the RDE 

software. 
United States Department of Agriculture

Agricultural Marketing Service, Science & Technology

Pesticide Data Program

SOP No: PDP SAMP Page 5 of 29

Title: Sampling Procedures for PDP

Revision: 2 Replaces: 07/01/2018 Effective: 06/05/2023

5.2 Relative Volume Information for Sampling Sites

Each State shall provide comparative volume information (quantity of the produce 

distributed compared to other sites) for each of the sampling sites on its master site list. The 

State will determine the “size measure” (comparative volume number) for the random selection 

of sampling sites. Size measures must be reviewed and updated as changes occur. If the State 

Sampling Manager encounters any problems in obtaining this volume information, they should 

inform the PDP Sampling Team and the NASS statistician. 

Internal SOPs for each State shall explain how the size measures are determined.

The size measures shall be the basis of random site selection. For example, on a scale 

of 1 to 10, a site distributing 100,000 pounds of produce may be given a size measure of 10, 

whereas a site distributing 10,000 pounds of produce may be given a size measure of 1. The site 

with a site measure of “10” will then be ten times more likely to be selected during any one 

month than the site with a measure of “1.”

States should try to further break down the volume information for a site into 

commodity groups (e.g., fresh produce, canned produce, and frozen produce). It is permissible, 

however, to have a single size measure for all available commodities or commodity groups. The 

NASS statistician can assist the States in making these determinations.

Sample collectors should also have this information with them in the field to aid them 

in making alternate site selections that are closely equivalent in size to the primary site.

5.3 Quarterly Selection of Sampling Sites

Each participating State shall be assigned a set number of samples to collect per 

commodity each month. The assigned number of samples per month is based on State 

population. This number shall remain constant from month-to-month throughout the calendar 

year, unless otherwise indicated.

NASS selects sites for quarterly sampling from a State’s master site list using 

probability proportional to size (PPS) and simple random sampling methods. These statistically 

sound selection methods are an important factor in the national representativeness of PDP 

sampling. State Sampling Managers should adhere to the sampling sites selected by NASS, and 

only switch sites out in rare circumstances.

Each participating State has the option of seeking advice and/or assistance from the 

NASS statistician regarding the quarterly site selection process. If a State chooses to perform 

its own quarterly site selection, the NASS statistician should be provided with all relevant 

information regarding the site selection process for approval. NASS should review all selection 
United States Department of Agriculture

Agricultural Marketing Service, Science & Technology

Pesticide Data Program

SOP No: PDP SAMP Page 6 of 29

Title: Sampling Procedures for PDP

Revision: 2 Replaces: 07/01/2018 Effective: 06/05/2023

procedures and the review should be documented by MPD and NASS. After the procedures 

have been approved by NASS, the State Sampling Manager shall send an email to MPD and 

NASS yearly indicating that the site selection procedures have not changed. NASS should rereview procedures every five years or when changes to the selection procedure are made. 

Sites shall be chosen for the entire quarter. Site selection criteria must be approved by 

NASS and requested by the State Sampling Manager 30 days prior to the start of the new quarter. 

The Sampling Manager may separate the selected sites into three distinct subsets of equal size 

at the convenience of the State (e.g., based on geographical location). The three groups may 

then be randomly assigned in a one-to-one manner to each of the three months in the quarter. 

Alternatively, the NASS statistician will randomly assign selected sites to months. 

No site, regardless of its size measure, shall have more than two samples of each 

commodity collected from the same site in a given month. Exceptions will be approved by MPD 

and the State Sampling Manager.

Every reasonable effort should be made to ensure the assigned number of samples are 

collected. Good communication between the sample collectors and their Sampling Managers, 

as well as between the State Sampling Managers and the laboratories is essential for detecting 

and correcting problems with missing, unavailable, or damaged samples. State Sampling 

Managers are encouraged to request assistance from MPD, if needed, to facilitate this process.

5.4 Quarterly Sampling Schedules, Fact Sheets, Laboratory Mailing Addresses, and 

Shipping Assignment Charts

Forty-five (45) days prior to the beginning of each new quarter, the PDP Sampling 

Team will provide State Sampling Managers and Laboratory Directors with a draft of the 

proposed PDP Quarterly Sampling Schedule, Shipping Assignment Chart, new Commodity 

Fact Sheets (when applicable), and laboratory mailing addresses for commodities to be collected 

in the new quarter. These schedules are initial suggestions only: State Sampling Managers and 

Laboratory Directors should review the documents through communication with each other and 

offer their preferred schedule to the PDP Sampling Team within 10 days of receipt of the 

documents. 

Thirty (30) days prior to the beginning of each new quarter, the final PDP Quarterly 

Sampling Schedule, Shipping Assignment Chart, and new Fact Sheets will be distributed. The 

PDP Sampling Team shall ensure that MPD sampling documents are updated on the PDP 

SharePoint site as changes occur. 

The Shipping Assignment Chart is updated quarterly to reflect program changes and 

is provided to the State Sampling Manager for distribution to the sample collectors. 
United States Department of Agriculture

Agricultural Marketing Service, Science & Technology

Pesticide Data Program

SOP No: PDP SAMP Page 7 of 29

Title: Sampling Procedures for PDP

Revision: 2 Replaces: 07/01/2018 Effective: 06/05/2023

State Sampling Managers shall review the laboratory mailing addresses distributed 

with the quarterly sampling information to ensure shipping information (i.e., contact person and 

address, including Building/Room number) is current for each State in their shipping provider 

account.

State Sampling Managers shall upload final copies of their monthly schedules to the 

PDP SharePoint site prior to the beginning of each new quarter by the following date: Quarter 

1, December 15; Quarter 2, March 15; Quarter 3, June 15; Quarter 4, September 15. Contact the 

PDP Sampling Team if you have trouble uploading your schedule.

The State Sampling Schedule shall be divided into the three months of the quarter.

Each month’s schedule shall include at least the following information:

▪ Sampling dates and commodity(ies) to be sampled

▪ Primary site numbers for each commodity

State Sampling Managers and laboratories shall coordinate sampling dates by the first 

day of the month prior to the start of the new quarter. This collaboration will allow the States 

time to finalize their sampling schedules.

State Sampling Schedules should never include any sites known to be inactive or that 

have declined participation in the program.

If necessary, the PDP Sampling Team will assist in the coordination between the State 

Sampling Managers and laboratories to agree on the selection of specific sampling weeks for 

the collection of the assigned number of samples per commodity. If necessary, the same 

commodity may be collected over a 2-day period; however, the receiving laboratory shall first 

be notified and must agree to the 2-day collection timeframe. When coordinating sampling 

weeks, each participant must also be made aware of any Federal and State holidays or other 

days when samples cannot be received at the laboratory.

States may group different commodities for collection on the same day at the same 

site.

Days of the week selected for sample collection may vary from State to State but shall 

be within the first three working days of the specified collection week. Monday and Tuesday 

are the preferred days for PDP sample collection. Exceptions to this schedule must first be 

approved by the receiving laboratory or may occur when one of the first three days of the 

specified collection week is a Federal or State holiday.

Friday sampling is not permitted for fresh or frozen commodities.
United States Department of Agriculture

Agricultural Marketing Service, Science & Technology

Pesticide Data Program

SOP No: PDP SAMP Page 8 of 29

Title: Sampling Procedures for PDP

Revision: 2 Replaces: 07/01/2018 Effective: 06/05/2023

Samples shall not be shipped out the day before a Federal or State holiday. Sampling 

States that have the option to hand deliver samples directly to the laboratory may arrive the day 

before a holiday if prior arrangements have been made with the receiving laboratory.

Additional information regarding sample collection, packaging, and shipping will be 

provided by the PDP Sampling Team 30 days prior to the beginning of the next quarter.

States performing PDP sample collection may be required to ship special collection 

samples to one or more State or Federal laboratories for analysis. Specific information regarding 

such assignments is provided in the PDP Sample Shipping Assignment Charts.

5.5 Assignment of Sample Collectors

Each State shall designate individuals to serve as their sample collectors.

Each participating State shall maintain a list of personnel involved in the collection of 

PDP samples. This list shall include the following: 

▪ Name 

▪ Assignment of sampling sites, cities, and geographical regions (if applicable)

▪ Whether the employee works on PDP full-time or part-time

▪ The estimated number of full-time equivalents (FTEs) used to fulfill the 

requirements of PDP sampling. This number shall include ALL aspects of 

sampling (e.g., sample collection, management of the program, tracking 

samples, clerical duties, etc.)

The PDP Sampling Team shall be notified of changes to sample collector information 

as changes occur.

State Sampling Managers or designee shall designate the number of commodity 

samples, with corresponding dates and sites, to be collected by each sample collector per month.

If a sample(s) will not be collected due to personal emergency, plant closure, weather 

conditions, etc., the sample collector shall notify the State Sampling Manager for reassignment 

to a different collector, alternate site, or sampling date.

If a sample collector cannot sample a product on the scheduled day, they shall 

immediately notify the State Sampling Manager. The State Sampling Manager (or designee) 

shall in turn notify MPD and contact the receiving laboratory to arrange for a resampling date.

Makeup samples shall be collected as soon as feasible and within the same month. It 

is permissible to collect a sample in a month following the scheduled sample collection date 

only under one of the following circumstances: (1) carrier delays result in the sample not 
United States Department of Agriculture

Agricultural Marketing Service, Science & Technology

Pesticide Data Program

SOP No: PDP SAMP Page 9 of 29

Title: Sampling Procedures for PDP

Revision: 2 Replaces: 07/01/2018 Effective: 06/05/2023

arriving in acceptable condition on their scheduled date near the end of a month and it is not 

possible to resample before the month’s end, (2) the sample has arrived at the laboratory in 

unacceptable condition and it is not possible to resample before the month’s end, (3) general 

unavailability of commodity, or (4) special circumstances arise where consultation is made 

between the collection State and MPD and it is determined that resampling a following month 

is deemed necessary. In any of these instances, MPD and the receiving laboratory must be 

notified for approval to “make up” the lost sample on a specified day the following month. 

Frequent make-ups are strongly discouraged. Over time, these actions may introduce 

undesirable bias in the PDP results. Make-up sampling shall not occur after the end of a calendar 

year (December 31) because the results would represent sampling efforts from two different 

years.

6. Sampling Procedures:

6.1 Primary, Alternate, and Proxy Site Sampling

Sample collectors are responsible for carrying with them the current version of 

necessary reference documents when sampling:

• State and PDP SOPs

• Quarterly Sampling Schedules and Shipping Charts

• Master Site List 

• Commodity Fact Sheets

• Paper SIFs

• Office, Lab, and PDP Contact Information and Mailing Address

Sample collectors should make every effort to collect samples at the scheduled primary 

site. A primary site is the scheduled, preferred site from the State's master site list of active sites 

where the sample should be collected. If it is determined that the commodity will not be 

available at the primary site, sample collectors should then choose an alternate site. If the 

commodity is not available at the primary or alternate site, a proxy (retail) site may be selected. 

Alternate sites are preferred to proxy sites. An alternate site is a back-up site from the 

State's master site list of active sites where the sample should be collected if it is not available 

at the primary site. The alternate site should be similar in size to the primary site, if feasible. If 

the first alternate site does not have the commodity(ies), the sample collector can procure 

samples from another site of similar size as long as the site has not been sampled for the same 

commodity during the sample selection period (usually a month, but this can be a fraction of a 

month when the product is scheduled for double or triple sampling).
United States Department of Agriculture

Agricultural Marketing Service, Science & Technology

Pesticide Data Program

SOP No: PDP SAMP Page 10 of 29

Title: Sampling Procedures for PDP

Revision: 2 Replaces: 07/01/2018 Effective: 06/05/2023

The selection of an alternate site number or vendor shall be totally objective in nature, 

with no pre-determination made regarding the date of last sampling, variety of commodity 

available, etc.

If the sample is collected at an alternate site, it is the sample collector’s responsibility 

to include the primary (scheduled) site code on the sample identification label that is affixed to 

each sample. See Module 4_Sample Collection_Prepare in the PDP Sampling Training Program 

for more information on sample IDs.

A proxy site is a retail store that may be in close proximity to the primary or alternate 

site and preferably receives the product directly from the primary or alternate site (in the 

distribution chain). Proxy sites are only to be used if the commodity is not available at the 

primary or alternate site. Proxy sites should be coordinated and approved by the State Sampling 

Manager. It is preferable, but not required, that proxy sites be supplied by the primary site. 

Samples collected from proxy sites must be in their original carton/container and 

collected from the retail store’s storage room, if possible. Only sealed, pre-packaged 

commodities may be collected from the retail store’s shelf provided all necessary sample 

information is available and can be verified. If a sample is collected from the retail shelf the 

sample must be sealed in a way to prevent cross-contamination and tampering (i.e., mesh bags

and zippered bags are not considered sealed for this purpose). Products that are not completely 

sealed and pre-packaged (e.g., fresh fruits and vegetables) should not be sampled from the front 

of the store at proxy locations as they have a higher potential for cross contamination and full 

product information may not be available (grower, packer, etc.).

If a proxy site is used for the collection of samples, the sample collector must note the 

following information on the eSIF: (1) the primary site code number and the correct Source ID 

code shall be recorded on the eSIF and on the sample identification label of the sample. Use 

Source ID code “P” for a single sample collected at a proxy site or “U-Z” for multiple samples 

collected at a proxy site (where the same site code number is entered for multiple samples);

and (2) the name and address or name and store number of the proxy site shall be entered in the

facility name field. Note: When a proxy site is used, there is no need to include the alternate 

site on the eSIF – only the originally assigned primary site and proper proxy site designation is 

required.

When more than one commodity is scheduled for sampling at the same site on the 

same date, all may be sampled from the primary or an alternate site/vendor, based on 

availability. All do NOT have to be sampled at the same site.
United States Department of Agriculture

Agricultural Marketing Service, Science & Technology

Pesticide Data Program

SOP No: PDP SAMP Page 11 of 29

Title: Sampling Procedures for PDP

Revision: 2 Replaces: 07/01/2018 Effective: 06/05/2023

6.2 Sample Size

MPD provides Fact Sheets that include collection information for each commodity. 

Fact Sheets contain statements regarding the size, variety, list of acceptable and unacceptable 

products for collection, details on specially requested eSIF information, and special 

packing/shipping instructions. Fact Sheets are not comprehensive but serve as a reference to be 

used in conjunction with PDP SOPs. Additional information regarding the sampling of specific 

commodities will be provided, as necessary, in writing to State Sampling Managers by the PDP 

Sampling Team. 

A sample is a group of produce/food items randomly collected by trained sample 

collectors from a box/crate at a specific collection site that has a unique site code and/or 

grower/packer/distributor/variety/lot number assigned to it.

Designated samples shall represent a given number of units, volume, or weight of a 

specific commodity collected at an assigned site on an assigned date. Each commodity sample 

is unique in that its label and associated eSIF contain information indicating it is different from 

other samples of the same commodity in at least one of the following areas: collection State; 

collection date; collection site; lot number; variety; or origin of grower, packer, or distributor.

The weight and number of units per sample, as designated by MPD, shall be collected 

for each commodity. Information regarding the amount of each sample collected will be 

provided in the Fact Sheet and Shipping Assignment Chart by the PDP Sampling Team prior to 

the beginning of each new quarter. Refer to Section 5.4 for more on quarterly sampling 

documents.

Sample collectors should collect samples that are as close to the target weight as 

possible. The use of a scale is strongly encouraged. 

Acceptable collection weights shall be within ±20% of the required sample size 

specified on the commodity Fact Sheet. Samples that weigh less or are smaller in size than the 

lowest end of these ranges are not acceptable; in these cases, the sample collector may be asked 

to re-sample.

Avoid collecting samples that are more than 20% over the target weight. Depending 

on the commodity, preparing the sampled portion can be very time consuming for lab staff.

For dry goods, grain products, and selected fresh produce as authorized by MPD, if 

the size or weight of the available sample is at least twice the required amount designated by 

the PDP Shipping Assignment Chart or Fact Sheet, the sample collector may open the container 

or package and remove the required amount while adhering to the following:
United States Department of Agriculture

Agricultural Marketing Service, Science & Technology

Pesticide Data Program

SOP No: PDP SAMP Page 12 of 29

Title: Sampling Procedures for PDP

Revision: 2 Replaces: 07/01/2018 Effective: 06/05/2023

▪ Once containers are opened, the sample collector shall take necessary 

precautions not to contaminate the sample.

▪ The sample collector shall ensure a representative sample is obtained by 

collecting from multiple spots throughout the length, width, and depth of the 

container. 

▪ Each participating State that performs subsampling shall have written 

procedures that include specific details on how to subsample from large 

containers as part of their internal sampling SOPs.

In special cases, States may be required to collect larger amounts per sample for 

Quality Assurance programs, or to split samples within the collection State. Sample collectors 

shall receive specific instructions from the State Sampling Manager regarding these exceptions.

If a sample will be analyzed by more than one laboratory location, it may be necessary 

for the sample collector to pick-up a duplicate sample for shipment to each appropriate 

laboratory. When applicable, instructions on sample duplication and shipping destination will 

be made in the PDP Shipping Assignment Chart.

6.3 Sample Collection

States should call the scheduled sampling site up to one business day in advance of the 

assigned sampling date to inquire about the availability of the commodity(ies) to be sampled. If 

a sample collector calls ahead to have the product available upon arrival, the sample collector 

shall request that such product be stored in a refrigerated area until pick up. 

If feasible based on site logistics, the sample collector should request that personnel at 

the collection sites randomly select a sample carton/container and have it available for the 

sampler to pick up at the site, only if a sample collector is not provided access to the collection 

facility. This collection method shall be an exception and shall be used only when necessary.

Personnel at collection sites may not select the sample from a box/crate.

When selecting a pallet/group to be sampled at a vendor site, the sample collector shall 

use an appropriate means of random selection that is outlined in the State’s internal Sampling 

SOPs. These SOPs shall be kept on file by the State Sampling Manager. The random selection 

process used by the sample collectors must be acceptable to both the NASS statistician and the 

State Sampling Manager.

Once a pallet/group has been randomly chosen, it is permissible to collect the entire 

sample from one box/crate. This is the preferred method. Samples may be selected from a 

variety of boxes/crates, provided that all boxes/crates are from the same lot number. Time 

stamps may vary, but the entire lot number must be the same. Contact the PDP Sampling Team 
United States Department of Agriculture

Agricultural Marketing Service, Science & Technology

Pesticide Data Program

SOP No: PDP SAMP Page 13 of 29

Title: Sampling Procedures for PDP

Revision: 2 Replaces: 07/01/2018 Effective: 06/05/2023

for questions about lot numbers (pdp.sampling@usda.gov).

Sample collectors shall take note if any expiration dates are recorded on the 

commodity that is being sampled. Sample collectors shall not collect product beyond its 

expiration date.

A “Best Used By” date is not the same as an expiration date and only describes 

possible quality changes over time. Sample collectors may collect samples after a “Best Used 

By” date if the integrity of the product has not been compromised.

Samples should be collected and bagged in the warehouse facility to avoid exposure 

to inclement weather, high or sub-freezing temperatures, and external contamination.

If only the exact sample amount(s) will be taken from the sampling site, the correct 

portion should be placed directly in the official sample container (bag) and sealed by the sample 

collector prior to exiting the facility. The entire case of product may, in agreement with the 

warehouse management, be taken to a more convenient location within the facility before 

removing the sample portion (e.g., area of the warehouse maintained at normal room 

temperature).

If necessary, an entire case or carton of product may be taken to a more convenient 

location before removing the sample portion, provided that sufficient precautions are taken to 

ensure the sample remains in optimum condition and is not contaminated by external factors. 

Perishable products must be stored at refrigerated temperatures if the transfer/transit 

time exceeds 30 minutes before packaging for shipment is initiated.

When collecting and packaging more than one sample, the sample collector shall 

prevent cross-contamination between samples. This process may be accomplished by utilizing 

disposable gloves, sterile hand wipes, or the washing of hands with soap and water between 

samples. If gloves are used (preferred method), they must be worn throughout the process of 

collecting the entire sample, properly discarded afterwards, and replaced by fresh gloves prior 

to collecting the next sample.

All supplies used for the collection, storage, and transport of samples must be free of 

any contaminants that may affect the analytical results. The sample collector shall ensure 

adequate sanitation from sampling through packaging to avoid contamination of product.

Samples shall be placed in a plastic bag. Paper bags may be used only for certain 

commodities with written permission from the PDP Sampling Team (paper bags may contain 

compounds that will affect analytical results).
United States Department of Agriculture

Agricultural Marketing Service, Science & Technology

Pesticide Data Program

SOP No: PDP SAMP Page 14 of 29

Title: Sampling Procedures for PDP

Revision: 2 Replaces: 07/01/2018 Effective: 06/05/2023

Loose samples or prepackaged containers (e.g., clamshells) shall be bagged using at 

least a two (2) millimeter thick plastic bag.

The bag containing the sample shall be sealed in a manner that any attempt to tamper 

with the contents would easily be noticed. A detailed description of the tamper-proofing method 

used shall be included as part of the State's internal SOPs for sampling. These SOPs must be 

kept on file by the State Sampling Manager. If the sample is hand delivered to the laboratory, 

tamper-proofing methods are optional, provided chain of custody is maintained.

 The tamper-proofing mechanism shall be initialed and dated by the sample collector 

who has bagged the sample. This information, coupled with a Quarterly Sampling Schedule that 

each laboratory maintains on file, will suffice to complete chain of custody requirements, and 

will allow initiation of sample processing and analysis in the event of a delayed eSIF.

Each sample bag shall be labeled with information that uniquely identifies the sample 

(i.e., the sample ID). The sample identification number is an 18-digit number that uniquely 

identifies each sample. The identification number must include: 2-letter State of collection, 6-

digit date (yy/mm/dd), 4-digit site code number, 2-letter commodity code, 3-character receiving 

laboratory code, and 1-letter source ID code when required. An example sample identification 

number is: CO-220817-0046-AP-WA1 (Colorado collected on August 17, 2022, at site 0046 a 

sample of fresh apples that will be analyzed at the Yakima, Washington laboratory).

A legible and permanently marked sample label shall be placed in a clear packing 

envelope affixed to the outside of each sample bag. Notations shall include: (1) unique sample 

identification information, (2) date, (3) sample collector name, and (4) alternate or proxy site 

information (if applicable). Note: For chain of custody purposes, the sample collector name on 

the sample label should match the sample collector on the eSIF.

All information may be pre-entered on the label except for the site number, date, and 

whether an alternate and/or proxy site was sampled. All information for a particular sample 

shall be unequivocally identified before leaving the site.

The use of whiteout is not permitted. Sample collectors should use a single line to 

cross-out the error and neatly write the correct information. It is best practice for samplers to 

initial and date the correction.

Simple errors (e.g., transposing lot numbers, labeling, etc.) do not require the initiation 

of a corrective action unless specified in an internal SOP.

If a deviation from the SOP is required, the change shall be approved in writing by the 

MPD Director.
United States Department of Agriculture

Agricultural Marketing Service, Science & Technology

Pesticide Data Program

SOP No: PDP SAMP Page 15 of 29

Title: Sampling Procedures for PDP

Revision: 2 Replaces: 07/01/2018 Effective: 06/05/2023

6.4 Collection of Specific Commodities

Fresh and Delicate Commodities

Fresh commodities refer to raw, whole produce (i.e., whole carrots, heads of lettuce, 

celery stalks, etc.). Not included are "prepared" produce, such as salad mixtures, sliced carrots 

or chopped celery, unless otherwise stated in writing by MPD. Items that are merely washed, 

brushed, or bagged are acceptable (i.e., leaf spinach, apples). 

Delicate commodities refer to fresh produce (e.g., strawberries, raspberries, peaches, 

etc.) that are highly susceptible to bruising, crushing and/or deterioration during the sampling, 

packaging, and shipping process or may deteriorate if exposed to excessive temperature or 

humidity.

Sample collectors shall be careful to select individual fruit or vegetables that are in 

good condition without any noticeable bruises, decay, or other visible defects.

Sample collectors should select fresh commodities with uniform maturity or ripeness.

Collection of under ripe or immature product is encouraged. Select fresh commodities that are 

not fully matured or ripened to ensure that the sample arrives to the laboratory in acceptable 

condition. For example, strawberries that contain a small amount of green outside flesh are 

acceptable. Some commodities may be difficult to determine maturity or ripeness, but 

collectors should use their best professional judgment when collecting samples. 

The sample should be culled to sort out overripe, bruised, decayed, or otherwise 

defective portions.

Sample collectors should exercise extreme caution when handling delicate 

commodities to minimize bruising or crushing.

If the sample collector transports fresh commodities from a location other than the 

collection site for packaging and shipping, necessary precautions should be taken to package 

the product in a container to minimize shifting of product during transit.

When samples are collected during the warm season, delicate commodities should be 

packaged in a pre-cooled insulated container to minimize damage from heat and humidity 

during transit. Maintaining recommended transit temperature for delicate commodities is 

crucial in ensuring that the product arrives in acceptable condition.

If a situation arises where the commodity cannot be packaged and shipped on the same 

day as sample collection, the commodity must be refrigerated. The State Sampling Manager, 

the receiving laboratory, and MPD shall be notified.
United States Department of Agriculture

Agricultural Marketing Service, Science & Technology

Pesticide Data Program

SOP No: PDP SAMP Page 16 of 29

Title: Sampling Procedures for PDP

Revision: 2 Replaces: 07/01/2018 Effective: 06/05/2023

Processed Commodities

Processed commodity refers to any food product that has undergone physical or 

chemical treatment resulting in a substantial change in the original state of the food. Frozen, 

canned, and dried foods are examples of processed commodities.

Sample collectors may not open frozen or canned products to obtain the appropriate 

size or weight unless previously approved in writing by MPD.

Sample collectors shall be careful to select products that are free from any noticeable 

dents, leakage, or other noticeable exterior damage.

Processed commodities shall consist of only the commodity to be sampled. For 

example, creamed corn, vegetable mixes, Italian style tomatoes, juice blends or cocktail 

juices, etc. are not acceptable.

In some instances, frozen, dried, or canned commodities may be substituted for fresh 

commodities. Any substitution information will be provided on commodity Fact Sheets or 

otherwise in writing by the PDP Sampling Team.

Occasionally, the collection of concentrated commodities will be alternated with 

ready-to-serve products, or a frozen commodity will be alternated with a liquid form based on 

the ratio of U.S. consumption or national sales. Additional information regarding sampling 

criteria for concentrated commodities will be provided in writing to the State Sampling 

Managers by the PDP Sampling Team unless otherwise stated in the Shipping Assignment 

Chart and commodity Fact Sheet.

Additional information regarding sampling criteria for processed products will be 

provided on the commodity Fact Sheets or otherwise in writing by the PDP Sampling Team.

6.5 Purchasing Samples

The sample collector shall make payment to the appropriate site/vendor(s) as 

necessary.

Exact method of payment (e.g., cash or State voucher) is determined by the individual 

States.

A receipt must be provided by the vendor. Original paper receipt or electronic copy of 

the receipt should be retained by the State for all sample payments for a two-year period. After 

two years, State Sampling Managers may transfer only electronic records of receipts to a Federal 

Records Center (FRC). Contact MPD with questions concerning the disposition or transfer of 
United States Department of Agriculture

Agricultural Marketing Service, Science & Technology

Pesticide Data Program

SOP No: PDP SAMP Page 17 of 29

Title: Sampling Procedures for PDP

Revision: 2 Replaces: 07/01/2018 Effective: 06/05/2023

records or if a State wishes to transfer records within a timeframe shorter than two years.

The sample collector may purchase either the required sample amount or the entire 

case of product as required by the vendor.

If an entire case is purchased, records must be kept and retained for two years by the 

States as to the disposal (donated, left with vendor, discarded, etc.) of the unused product. 

Donation of excess product is encouraged, and donation records should be sent to MPD 

annually, as requested.

Payment for samples should approximate the local retail price, but an additional 

amount may be added, as appropriate, for the vendor's administrative costs. Prices for PDP 

commodities may fluctuate. Contact the PDP Sampling Team with concerns regarding 

commodity prices. 

Specific procedures/requirements regarding the purchase of PDP samples shall be 

explained as part of the State's internal SOP for sampling.

7. Packing and Shipment of Samples:

7.1 Packing Procedures for All Commodities

These packing procedures provide minimum PDP requirements and are presented as 

general guidelines. Each participating State shall, as part of their internal sampling SOPs, have 

on file written procedures that include specific details as to the materials and procedures used 

for packing the PDP samples. Both the PDP SOP and the State's internal SOPs will be used as 

the measure of compliance during MPD sampling reviews.

Each sample shall be packed by the sample collector.

Samples of commodities that require refrigerated temperatures to maintain their 

original integrity shall be placed in a pre-cooled, insulated shipping container.

Use enough frozen cold packs to maintain the product cool during transit. Most 

products will not be shipped via temperature-controlled transportation. Cold packs should be 

insulated from the commodity by creating a barrier with a material that will prevent direct 

contact with the commodity, thereby preventing any “freezer burn.” Maintaining recommended 

transit temperature is crucial to ensure that the product arrives in an acceptable condition. Loose 

wet ice is not an acceptable coolant material.

Sample collectors shall use shipping containers that are the correct size for the 

commodity being shipped.
United States Department of Agriculture

Agricultural Marketing Service, Science & Technology

Pesticide Data Program

SOP No: PDP SAMP Page 18 of 29

Title: Sampling Procedures for PDP

Revision: 2 Replaces: 07/01/2018 Effective: 06/05/2023

Samples shall be packed in an insulated container (e.g., Styrofoam lined or thermal 

liner) for shipping.

Sample collectors may place a solid polyethylene (plastic) bag liner in the insulated 

container to ensure against inadvertent leakage. The liner should be closed and properly sealed.

Commodities should be arranged compactly inside the insulated container allowing 

space for ice packs.

Sufficient room shall be provided inside the shipping box so that samples are not 

squeezed, broken, bent, or bruised and there is no danger of rupturing sealed bags.

The sample collector shall use enough packing materials (i.e., recycled paper, white 

butcher paper, and/or bubble wrap) to prevent movement of the produce during transit. These 

packing materials also provide insulation against sub-freezing temperatures during air transport. 

Newspaper, brown butcher/kraft paper, and shredded computer paper are not acceptable 

packaging materials.

If the shipping container will not change hands, thereby maintaining chain-of-custody, 

it is not necessary for the packing box to be sealed (i.e., the collector “hand” delivers the 

sample(s) to the laboratory). The sample collector must ensure that the container lid fits tightly 

and securely so that it does not open during transit.

7.2 Packing Fresh and Delicate Commodities

If commodities have been grouped for collection, it is permissible for more than one 

commodity type to be placed directly in the same shipping container. When packaging more 

than one fresh commodity type, sample collectors should package together fresh commodities 

that have similar temperature, moisture, packaging, and shipping requirements to minimize 

product degradation. It is recommended that only commodities with similar sizes, weights, 

cooling requirements, and ethylene sensitivities be placed together in the same container.

Information regarding these requirements is provided on each commodity Fact Sheet.

For light-weight commodities (e.g., blueberries, raspberries, etc.) there is no limit on 

the number of like samples that may be shipped together in one box/container, as long as there 

is no possibility of crushing or damaging the samples. For heavier commodities such as 

nectarines and peaches, no more than two (2) samples shall be shipped together in the same 

box/container.

7.3 Packing Processed Commodities

Processed products shall be packed in a manner to conserve space, maintain 
United States Department of Agriculture

Agricultural Marketing Service, Science & Technology

Pesticide Data Program

SOP No: PDP SAMP Page 19 of 29

Title: Sampling Procedures for PDP

Revision: 2 Replaces: 07/01/2018 Effective: 06/05/2023

temperature, and to minimize movement of product to avoid the rupturing or crushing of 

containers while in transit.

When sampling glass containers, such as baby foods, protect individual containers in 

bubble wrap to prevent them from breaking during transit. 

Frozen samples must be packaged using a method that will ensure that the samples 

arrive at their receiving laboratory cold-to-the-touch.

7.4 Shipment of PDP Samples

To help reduce sampling costs, the reuse of shipping containers and ice packs is 

encouraged. If a sampling State elects to have a shipping container and packaging materials 

returned, a return shipping label must be included inside the box. Return shipping should be 

accomplished by the most cost-effective means possible.

The sample collector and/or State Sampling Manager shall be responsible for ensuring 

that samples are shipped to the correct laboratory(ies) as provided quarterly on PDP Sample 

Shipping Assignment Charts.

Individual commodity Fact Sheets shall be referenced for shipping instructions. 

Special shipping requirements will be specified in the Packing and Shipping section of the 

individual commodity Fact Sheet.

All samples must be shipped by a service that results in the sample arriving at the 

assigned laboratory no later than the day following sample collection. Note: Some commodities 

are permitted to be shipped using ground shipping. See commodity Fact Sheet for specific 

shipping instructions. State Sampling Managers are responsible for following-up to determine 

if the samples are arriving within the established timeframe, are in acceptable condition, and/or 

taking action (e.g., changing delivery services) as needed if they are not.

Sample collectors should receive prior approval from the laboratory for any samples 

arriving on Friday or the day before a holiday. Laboratory staff may not be available on days 

immediately before or after a holiday. 

Copies of shipping transactions for all samples shall be kept on file by the State in case

shipping problems arise.

7.5 Shipping Fresh and Delicate Commodities

The sample collector should label the outside of the box with statements such as: 1) 

FRAGILE, 2) THIS END UP, 3) PERISHABLE PRODUCT, or 4) REFRIGERATE UPON 
United States Department of Agriculture

Agricultural Marketing Service, Science & Technology

Pesticide Data Program

SOP No: PDP SAMP Page 20 of 29

Title: Sampling Procedures for PDP

Revision: 2 Replaces: 07/01/2018 Effective: 06/05/2023

RECEIPT.

Fresh and/or perishable commodities may be shipped to arrive at their respective 

laboratories at the latest by 5:00 p.m. on the day following sample collection if refrigerated 

internal temperatures can be maintained throughout transit. Receiving laboratories must approve 

this shipping schedule; otherwise, a 10:00 a.m. receiving time on the day following sample 

collection shall be followed.

If perishable samples are hand delivered to a local State office, shipping facility, or 

State laboratory, sample collectors shall place the product in a pre-cooled insulated shipping 

container along with enough ice packs to ensure refrigerated temperatures during transport.

Perishable commodities shall not be shipped on Friday or the day before a Federal or 

State holiday. Exact dates for observed Federal Holidays are included in the Quarterly Sampling 

Memo.

7.6 Shipping Processed Commodities

Frozen samples shall be shipped frozen by the sample collector on the date of 

collection in a manner that ensures they arrive at least “cold-to-the-touch” at the receiving 

laboratory. For “delicately frozen” commodities (i.e., fish), it is suggested that the product be 

frozen overnight before shipping.

Most processed samples will be shipped at ambient temperature and can be shipped 

by ground to save on shipping costs. See commodity Fact Sheet for specific shipping details.

8. Sample Information Forms and Chain of Custody:

8.1 PDP General Requirements

Sample Information Forms (SIFs) allow MPD to track the number and type of samples 

collected, the number of missing samples, and the reason(s) why a sample was not 

collected/analyzed.

Electronic SIF (eSIF) is considered the default sample data recording option and 

should be used when feasible. The term eSIF will be used throughout this document. 

The sample collector shall ensure that one eSIF is completed for each assigned sample.

If a sample will not be collected, an eSIF must be completed for each sample not 

collected and emailed to MPD. If paper SIFs are used for notification of an uncollected sample, 

the paper SIF must be sent or emailed to the receiving laboratory who in turn notifies MPD.
United States Department of Agriculture

Agricultural Marketing Service, Science & Technology

Pesticide Data Program

SOP No: PDP SAMP Page 21 of 29

Title: Sampling Procedures for PDP

Revision: 2 Replaces: 07/01/2018 Effective: 06/05/2023

In addition to sample identification information, the eSIF shall include: (1) available 

information regarding Country of origin, grower, packer, distributor, and lot number, and (2) 

details pertaining to agricultural practices employed during or after production such as 

organically grown or chemically treated with sanitizers. As this information can be time 

consuming to input, entries such as “post-harvest treatment applied” are acceptable. If available, 

this type of information can be found on the commodity container (box/crate) and should be 

taken from the packaging closest to the sample that has the needed information (e.g., for citrus 

in a netted bag inside a wax box, the netted bag is closest to the sample). This information should 

be entered in the free-form Comment field of the eSIF.

Sample collectors should make every attempt to locate and record origin and 

grower/packer/distributor information.

Product variety information must be included on the eSIF, when available.

It is important that sample collectors complete all necessary fields of the eSIF. Freeform fields such as Variety, Brand Name, Expiration Date, Packer Name, Grower Name, 

Distributor Name, and Lot Number/Other ID, must not be left blank. If the requested 

information cannot be found on the commodity container/box/carton, the sample collector shall 

enter “NA” in the field provided. 

When proxy (retail) sites are used for sample collection, the sample collector shall 

include the appropriate Source ID in the Sample ID and the proxy site’s name (or store number),

and address in the Facility Name field (refer to Section 6.1.8).

It is strongly recommended that when typical sample information is not available, the 

sample collector record any other available identification information that could be used to track 

the sample in the Comments field of the eSIF.

Paper versions of the SIF are acceptable only in instances where problems occur with 

the use of the electronic version (power outages, computer shutdowns, etc.). When paper SIFs 

are used, copies must be emailed to the appropriate laboratory within a timeframe to coincide 

with sample arrival (refer to Section 8.2.7). If computer problems prevent scanning and emailing 

the paper SIF, refer to instructions in Section 7.1.11.

MPD occasionally requests that special information (specific ingredients, generic 

varieties, etc.) be recorded and collected for certain commodities. Sample collectors are required 

to include this information on their eSIFs. The Fact Sheets list these special requests and explain 

where the information should be recorded on the eSIF. 

If, due to illness, natural disaster, weather conditions, etc., a State is unable to collect 
United States Department of Agriculture

Agricultural Marketing Service, Science & Technology

Pesticide Data Program

SOP No: PDP SAMP Page 22 of 29

Title: Sampling Procedures for PDP

Revision: 2 Replaces: 07/01/2018 Effective: 06/05/2023

the scheduled sample(s), a new collection date shall be rescheduled for a different week/day of 

that month with the approval of the receiving laboratory. When the items are collected on the 

rescheduled date, the new collection date shall be entered on the eSIF.

If re-scheduling must occur during the following month the new collection date shall 

be entered on the eSIF, along with a brief explanation of the delay. Refer to Section 5.5.7 for

exceptions.

Once the sample collector has mailed/emailed the eSIF, no changes shall be made to 

the document without approval from the State Sampling Manager.

8.2 Electronic Sample Information Forms (eSIFs)

Sample information is entered on a windows-based laptop, desktop, or tablet

computer.

Training for all sample collectors on the use of the eSIF application is required.

Sample information shall be entered into the eSIF application as specified in the RDE

eSIF User Guide, which is available on the PDP SharePoint site. 

If sample information is pre-entered into the sample collector’s eSIF device, all 

entered data should be reviewed AFTER sample collection is completed to ensure the 

information is correct for samples that were collected. Reviewing sample information is 

important to ensure that accurate comparisons can be made between the sample once it is 

received at the laboratory and its corresponding eSIF.

Multiple samples may be exported from the eSIF application into a text file that shall 

be transmitted to MPD.

All eSIF text files shall be e-mailed to the following designated USDA account: 

amsmpo.data@usda.gov.

It is preferred that eSIF files should be emailed on the same day as sample collection. 

However, eSIF files must be emailed no later than 12:00 p.m., Eastern Time, on the day 

following sample collection.

New RDE program information shall be updated on State’s field computers (handheld 

or laptop computers) when supplied by MPD.
United States Department of Agriculture

Agricultural Marketing Service, Science & Technology

Pesticide Data Program

SOP No: PDP SAMP Page 23 of 29

Title: Sampling Procedures for PDP

Revision: 2 Replaces: 07/01/2018 Effective: 06/05/2023

8.3 Paper Sample Information Forms

It is acceptable for sample collectors to hand-write sample information on a paper SIF, 

if necessary, for later recording on the eSIF. If this practice is performed, the sample collector 

must: (1) record all necessary sample information on the paper SIF BEFORE leaving the site, 

(2) sign and date the paper SIF and, (3) keep all paper SIFs on file for a minimum of two years 

because they are considered “raw data.” 

After two years, State Sampling Managers may transfer electronic copies of the paper 

SIF forms to a FRC (refer to procedures and templates in SOP PDP-ADMIN). MPD should be 

contacted for any questions concerning the disposition or transfer of records or if a State wishes 

to transfer records within a timeframe shorter than two years.

Sample collectors shall ensure that all applicable portions of the form are PRINTED

neatly and legibly. Mistakes on the SIF shall be marked through with a single line and dated 

and initialed at the time of the correction.

The paper SIF must be signed and dated by the sample collector at the time of 

collection. If someone else collects the sample in place of the originally assigned collector, that 

individual must sign the form. Forms should never be signed prior to sample collection.

If computer/electronic problems occur that prohibit the use of eSIFs, paper SIFs for

both collected and uncollected samples shall be placed in a separate re-sealable plastic bag in 

the same shipping container as the corresponding sample, with any other samples collected by 

the sample collector, and mailed to the designated laboratory(ies).

Sample collectors shall refer to the PDP SIF instruction sheets for further explanation 

on filling out the form. Instructions may be found on the PDP SharePoint site in the PDP 

Sampling section.

8.4 Chain of Custody

Chain of custody requirements ensure the chronological possession of samples as they 

pass from sample collector to the carrier to the laboratory.

The sample collector shall ensure that all chain of custody requirements are fulfilled.

See Section 6.3.16.

When eSIFs are used, written documentation (a paper SIF inside the shipping 

container) is unnecessary if all sample collection information entered in the eSIF is received by 

the laboratory.
United States Department of Agriculture

Agricultural Marketing Service, Science & Technology

Pesticide Data Program

SOP No: PDP SAMP Page 24 of 29

Title: Sampling Procedures for PDP

Revision: 2 Replaces: 07/01/2018 Effective: 06/05/2023

Paper SIFs serve as written documentation of the sample collector’s possession of the 

sample and shall include the commodity collected, the site code, the date the samples were 

collected, the signature of the individual collecting and packaging the samples, and the date of 

transfer to the carrier.

9. Training and Evaluation of Sample Collectors:

9.1 Training for Sample Collectors

PDP-based training and evaluations serve as tools from which to teach and judge the 

sample collector’s level of knowledge and skills for PDP sampling operations.

PDP has developed a standardized training program for use by the States. The program 

consists of eight PowerPoint modules detailing each aspect of the sampling process, a video on 

packing delicate commodities, and an Appendix. The training program can be found under the

PDP Sampling section of the PDP SharePoint site. 

Training shall be conducted at least once a year to ensure that sample collectors have 

an acceptable level and working knowledge of PDP SOPs, the PDP RDE application, and 

current program updates. Although it is preferable that collectors meet in person with their State 

Sampling Manager for their training needs, it is acceptable for Sampling Managers to deliver 

training via electronic means.

Sample collectors shall be updated on PDP program changes at the time State 

Sampling Managers are notified of such changes by MPD.

Sample collectors shall be provided with reference documents listed in Section 6.1.1.

New sample collectors shall become familiar with PDP SOPs, view applicable training 

presentations, and spend ample time in the field collecting, packaging, and shipping PDP 

commodities with their respective State Sampling Manager, or designee, prior to initiating their 

own collections.

Sample collectors shall be provided and become familiar with all collection, 

packaging, and shipping supplies that are approved for use by their State Sampling Manager, or 

designee.

State Sampling Managers shall keep on file a record of the training each sample 

collector receives and shall have such records available for viewing by MPD when requested. 

(Refer to SOP PDP-ADMIN).
United States Department of Agriculture

Agricultural Marketing Service, Science & Technology

Pesticide Data Program

SOP No: PDP SAMP Page 25 of 29

Title: Sampling Procedures for PDP

Revision: 2 Replaces: 07/01/2018 Effective: 06/05/2023

9.2 Evaluation of Sample Collectors

Sample collector evaluations shall be conducted once a year or more frequently as 

necessary.

As part of the sample collector’s routine evaluation, the State Sampling Manager, or 

designee, shall accompany the sample collector into the field to observe their sample collection 

techniques and knowledge of PDP SOPs.

Evaluations shall include a review of eSIFs to ensure sample information is being 

obtained and recorded in an acceptable manner.

Collection problems shall be corrected as they occur and shall include sample collector 

re-training as necessary.

Sampling Managers shall keep a record on file of the evaluations each sample collector 

receives and shall have such records available for viewing by MPD when requested. (Refer to 

SOP PDP-ADMIN).

10. Special Sampling Scenarios:

10.1 Makeup and Resample

When samples are not collected on the assigned day due to unavailability of 

commodities, weather related impacts, etc., the sample should be collected at a different time 

and in consultation with MPD and the receiving laboratory (Refer to Section 5.5.7). 

A makeup sample is a sample that was not collected on the assigned day and will be 

collected on a different scheduled date. State Sampling Managers should coordinate the 

collection of a makeup sample with the receiving laboratory. 

A resample is a sample that was collected on the assigned day but could not be 

analyzed by the testing laboratory. A resample may be necessary when the sample is damaged 

in transport, arrives to the laboratory in poor condition, or is unacceptable based on commodity 

criteria (weight, variety, etc.). A resample may be required after a viable sample has been 

received by the testing laboratory.

10.2 Double or Triple Sampling

Double or triple sampling refers to extra samples collected during a specified period 

to make up for times (or seasons) when certain commodities are unavailable and therefore are 

unable to be collected. This sampling scenario will generally occur during a commodity’s peak 
United States Department of Agriculture

Agricultural Marketing Service, Science & Technology

Pesticide Data Program

SOP No: PDP SAMP Page 26 of 29

Title: Sampling Procedures for PDP

Revision: 2 Replaces: 07/01/2018 Effective: 06/05/2023

availability months (e.g., fresh cranberries in the 4th quarter).

Double sampling is defined as the collection of twice the assigned monthly number of 

samples per commodity; for example, double sampling of a given commodity that normally has 

7 samples collected per month would entail the collection of 14 samples for that commodity 

that month.

Triple sampling is defined as the collection of three times the assigned monthly 

number of samples per commodity; for example, triple sampling of a given commodity that 

normally has 7 samples collected per month would entail the collection of 21 samples for that 

commodity that month.

Double or triple sampling shall be conducted during the entire designated collection 

time period unless otherwise directed by MPD.

Double or triple sampling must be approved by MPD and the NASS statistician and

coordinated with the laboratory(ies) receiving the samples.

Sampling states that use NASS for quarterly site selection will require additional sites 

for double and triple sampling. For every month in a quarter a commodity is double sampled, 

the number of subsets is increased by one. When there is triple sampling, the number of subsets 

is increased by two.

Each extra sample shall be collected at a different site OR on a different day than the 

regularly collected sample of the same commodity. More than one sample must not be collected 

from the same site on the same day (Refer to Section 6.2.3 for exceptions).

Extra samples may be collected at proxy sites, after attempting to collect at the 

scheduled primary site and checking for the commodity at an alternate site. A proxy site for a 

particular distribution center will be considered a completely different site than the primary 

distribution center site. Guidance in 10.2.10 should be followed with regard to selecting 

samples.

The sample collector shall ensure that all requested sample information is recorded 

correctly on the eSIF. Omission of pertinent data may void the extra sample and resampling 

may be required.

If double or triple sampling is performed, the sample collector shall ensure that each 

sample is taken from a different grower, packer, or distributor, or is a different variety. If a 

product with a different grower, packer, or distributor cannot be found (preferred selection), it 

is acceptable to sample second or third products with a different lot number. 
United States Department of Agriculture

Agricultural Marketing Service, Science & Technology

Pesticide Data Program

SOP No: PDP SAMP Page 27 of 29

Title: Sampling Procedures for PDP

Revision: 2 Replaces: 07/01/2018 Effective: 06/05/2023

When two or more samples are collected from the same site on the same day with 

different grower, packer, or distributor, or is a different variety or lot number, differentiation 

shall be made between the samples by entering A through M for a primary site or U through Z 

for a proxy site in the Source ID Code field of the eSIF and on the sample identification label.

If special sampling or different labeling distinctions are requested by MPD, the sample 

collector will find instructions on individual commodity Fact Sheets.
United States Department of Agriculture

Agricultural Marketing Service, Science & Technology

Pesticide Data Program

SOP No: PDP SAMP Page 28 of 29

Title: Sampling Procedures for PDP

Revision: 2 Replaces: 07/01/2018 Effective: 06/05/2023

Revised By: Amy Gaines Date 

Revised By: Jessica Murillo Date

Monitoring Programs Division 

1400 Independence Ave, SW

Washington, DC 20250

Reviewed By: Brian Regan Date

Presiding Member of PDP Sampling Advisory Group

Michigan Department of Agricultural and Rural Development

1615 South Harrison Road

East Lansing, MI 48823

Approved By: Brenda Foos Date

PDP Director, Monitoring Programs Division 

1400 Independence Ave, SW

Washington, DC 20250

Original signed by Brian Regan 6/5/2023

Original signed by Brenda Foos 6/6/2023

Original signed by Amy Gaines 6/5/2023

Original signed by Jessica Murillo 6/5/2023
United States Department of Agriculture

Agricultural Marketing Service, Science & Technology

Pesticide Data Program

SOP No: PDP SAMP Page 29 of 29

Title: Sampling Procedures for PDP

Revision: 2 Replaces: 07/01/2018 Effective: 06/05/2023

Revision 2 June 2023 Monitoring Programs Division

• Updated references

• Changed section order for easier readability

• Removed redundant information

• Defined sampling frame

• Added language that retail sites should not be included on Master Site List

• Updated PDP Sampling Manager to PDP Sampling Team 

• Removed references to “faxing” and “printing” of documents

• Updated language regarding expired products

• Defined how often MPD provides copies of Master Site List to States for comparison

• Defined how often NASS must review site selection procedures for states that select their own 

sites

• Added language that Sampling Mangers should review provided contact information quarterly

• Added language on PDP Sampling Training Program

• Added requirement for training on RDE eSIF application for sample collectors

• Added language stating that Monday and Tuesday are the preferred sampling days

• Removed sampling objective requirement

Revision 1 June 2018 Monitoring Programs Division

• Clarified language in section 5.1.6 that alternate site info is not required for proxy site samples

• Added language for subsampling large containers to section 6.3.5

• Added language that simple errors do not require a CA unless specified in internal SOPs to 

section 6.4.1.1

• Specified paper SIFs do not need to be faxed to MPD in section 8.3

• Dropped the requirement for duplicate labels in section 8.4.4