FSNS is ramping up to test for over 400 pesticides in low-fat foods such as vegetables, fruits, and grains. The FSNS validated method employs QuEChERS with GC-MS/MS and LC-MS/MS detection to assure the presence of each detected pesticide is confirmed and accurately measured. As an add-on, each measured residue will include the US allowable Maximum Residue Levels (MRL) and of major countries of interest.
FSNS Method Summary
The FSNS pesticide screen uses QuEChERS with GC-MS/MS and LC-MS/MS detection. QuEChERS (Quick Easy Cheap Effective Rugged Safe) is an extraction and clean-up protocol developed by a USDA research group that uses special solvents with cleaning salts to collect all pesticide residues present in the food. That extract is then further cleaned using a dSPE procedure. The pesticides are then detected and quantified by using both Liquid Chromatography Tandem Mass Spectrometry (LC-MS/MS) and Gas Chromatography Tandem Mass Spectrometry (GC-MS/MS). Our state-of-the-art mass spectrometers are highly sensitive so the method has precise quantification capabilities of pesticides at levels down to 0.010 ppm to support regulatory compliance.
Regulatory Oversight
The U.S. government defined pesticides in the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) as “any substance or mixture of substances intended for preventing, destroying, repelling, or mitigating any pest, [and] any substance or mixture of substances intended for use as a plant regulator, defoliant, or desiccant.”1
For pesticides that are allowed to be applied to specific foods being grown, transported, or stored, EPA/FDA has set MRLs for specific pesticide-food combinations.2 For example, in the US, linuron is allowed to be used on carrots with an MRL of 1 ppm and chlorpyrifos on wheat at 0.5 ppm. If an allowed pesticide is detected above its MRL, the food is considered adulterated and subject to seizure.
If a pesticide found in a food does not have an allowable MRL, the food is also considered adulterated and subject to seizure. No regulatory agency has an official “default acceptable level” for pesticides without MRLs but generally, a limit of 0.010 ppm is considered the typical value such occurrences are compared against. It should be noted that regulatory agencies reserve the option to evaluate each occurrence on a case-by-case basis which may result in different interpretations.
For international trade, CODEX has established MRLs for each food group.3 Each country also has its own MRL allowances such as the EU4 so it is recommended their regulations be reviewed to reduce the risk of detention.
A Short Testing History
Pesticide residue analytical methods historically tested for single residues to determine if the levels of allowed pesticides were below acceptable levels. These analytical methods then evolved into multi-residue screens where groups of pesticides were analyzed at the same time. These groups were Organochlorides (OC), Organonitrogens (ON), Organophosphorous (OP) and methyl-carbamates with each group requiring different instruments to detect the group-specific molecular components.
The current industry norm is a broader multi-residue screen simultaneously testing for all the pesticide groups. This approach is commonly referred to as “QuEChERS with GC-MS/MS and LC-MS/MS detection” and is now the prevalent protocol to simultaneously analyze for the presence and amounts of hundreds of pesticides in food and foodstuffs. The MS/MS detection also confirms the identity of the detected pesticides to prove they are present at the measured levels. While the Limit of Detection for each pesticide in different foods does vary, the target LOD of 0.010 ppm is included in the FSNS method.
1 https://www.epa.gov/enforcement/federal-insecticide-fungicide-and-rodenticide-act-fifra-and-federal-facilities
2https://www.epa.gov/pesticide-tolerances
3http://www.fao.org/fao-who-codexalimentarius/codex-texts/dbs/pestres/pesticides/en/
4https://ec.europa.eu/food/plant/pesticides/eu-pesticides-db_en
