🍎 Pesticide multi-residue (QuEChERS)
In short
Multi-residue analysis of pesticide residues in food by QuEChERS method (acetonitrile extraction + dSPE) with GC-MS/MS and LC-MS/MS detection. The test is performed according to PN-EN 15662:2018; Number of analytes: 200–500 pesticides simultaneously. The procedure comprises 11 steps (about 2 h 30 min–3 h 20 min in total); it is used for: Official control of pesticide residues in food (EC Reg. 396/2005), Monitoring of imported fruits and vegetables (RASFF program), Quality control of organic products (BIO).
At a glance
- Standard: PN-EN 15662:2018
- Category: Food Chemistry
- Procedure steps: 11
- Total time of stages: 2 h 30 min–3 h 20 min
- Number of analytes: 200–500 pesticides simultaneously
- Limit of quantification (LOQ): 0.001–0.01 mg/kg
- Recovery: 70–120% (SANTE/11312 acceptance criterion)
Overview
QuEChERS (Quick, Easy, Cheap, Effective, Rugged, Safe) is a revolutionary sample preparation method for multi-residue pesticide analysis in food. Developed in 2003 by Anastassiades and colleagues, it has become the European standard EN 15662 and is used by food control laboratories worldwide.
The method involves extraction of homogenized food sample with acetonitrile (MeCN) with simultaneous phase partitioning using salts (MgSO₄ + NaCl + citrates as buffers). Then the extract is cleaned by dispersive solid-phase extraction (dSPE) using sorbents (PSA, C18, GCB) removing co-extracted matrix components (fats, chlorophyll, sugars, organic acids).
The cleaned extract is analyzed simultaneously by GC-MS/MS (volatile and semi-volatile pesticides — organochlorines, organophosphates, pyrethroids) and LC-MS/MS (polar and thermolabile pesticides — carbamates, neonicotinoids, triazines, strobilurins). Wide analytical scope covers 200–500 pesticides in one test, with limits of quantification at 0.001–0.01 mg/kg level.
EN 15662 method uses citrate buffering (pH 5–5.5), which ensures stability of pH-dependent pesticides and good recoveries for a wide spectrum of analytes. This is the preferred method by EFSA and official food control laboratories in the EU for routine pesticide residue monitoring in fruits, vegetables, cereals, and processed food.
Method principle
Sample (10 g homogenate) is extracted with 10 mL acetonitrile by vigorous shaking. Addition of extraction salts (4 g MgSO₄, 1 g NaCl, 1 g sodium citrate dihydrate, 0.5 g disodium citrate sesquihydrate) causes phase separation and buffering to pH 5–5.5. After centrifugation, an aliquot of organic phase is cleaned by dSPE — shaking with 150 mg MgSO₄ + 25 mg PSA (removing fatty acids, sugars) ± 25 mg C18 (removing fats) ± 2.5 mg GCB (removing chlorophyll). Cleaned extract is analyzed by GC-MS/MS and/or LC-MS/MS in MRM (Multiple Reaction Monitoring) mode with identification based on retention time and ion ratio.
Applications
- Official control of pesticide residues in food (EC Reg. 396/2005)
- Monitoring of imported fruits and vegetables (RASFF program)
- Quality control of organic products (BIO)
- Testing of cereals, tea, spices, and processed food
- HACCP systems and supplier control in food industry
- GlobalGAP / IFS / BRC certification
- Testing under EFSA monitoring programs
Key parameters
| Parameter | Value |
|---|---|
| Number of analytes | 200–500 pesticides simultaneously |
| Limit of quantification (LOQ) | 0.001–0.01 mg/kg |
| Recovery | 70–120% (SANTE/11312 acceptance criterion) |
| Sample size | 10 g homogenate + 10 mL MeCN |
| Sample preparation time | 15–30 min (QuEChERS) |
| Detection technique | GC-MS/MS (EI) + LC-MS/MS (ESI±) |
Standard
- Standard number
- PN-EN 15662:2018
- Title (PL)
- Żywność pochodzenia roślinnego — Wielopozycyjne metody oznaczania pozostałości pestycydów z zastosowaniem GC-MS i/lub LC-MS/MS po ekstrakcji/podziale acetonitrylem i oczyszczaniu metodą dyspersyjnej SPE (metoda QuEChERS)
- Title (EN)
- Foods of plant origin — Multimethod for the determination of pesticide residues using GC- and LC-based analysis following acetonitrile extraction/partitioning and clean-up by dispersive SPE — QuEChERS method
Step-by-step procedure
-
Sample homogenization
Homogenize entire laboratory sample (min. 200 g fruits/vegetables) in blade homogenizer. Take 10 g into 50 mL tube.
-
Extraction
Add 10 mL acetonitrile. Shake vigorously for 1 min (manually or on shaker).
-
Extraction salts addition
Add EN salt kit: 4 g MgSO₄ + 1 g NaCl + 1 g sodium citrate + 0.5 g disodium citrate sesquihydrate. Shake 1 min.
-
Centrifugation
Centrifuge 5 min at ≥4000 rcf. Acetonitrile phase with pesticides — upper layer.
-
dSPE cleanup
Take 6 mL upper phase into dSPE tube (150 mg MgSO₄ + 25 mg PSA ± C18 ± GCB). Shake 30 s.
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Cleanup centrifugation
Centrifuge 5 min at ≥4000 rcf. Collect cleaned extract into autosampler vial.
-
Internal standards addition
Add internal standards (isotope-labeled or analogues) for recovery control and matrix effect compensation.
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GC-MS/MS analysis
Inject 1–2 µL into GC-MS/MS. DB-5ms or HP-5ms column (30 m). MRM mode. Temperature program 60→300°C.
-
LC-MS/MS analysis
Inject 5–10 µL into LC-MS/MS. C18 column (100 mm). Mobile phase: H₂O/MeCN + 0.1% HCOOH. MRM ESI± mode.
-
Identification and quantification
Identification: retention time ± 0.1 min + MRM ion ratio ± 30%. Quantification: matrix-matched calibration.
-
Quality control
Every series: blank, fortified sample (spike), CRM. Recovery 70–120%, RSD < 20% (according to SANTE/11312/2021).
Required equipment and apparatus
| Equipment | Example | Indicative price |
|---|---|---|
| LC-MS/MS system | Shimadzu LCMS-8060NX, Agilent 6470C, Waters Xevo TQ-XS | 600 000–1 200 000 PLN |
| GC-MS/MS system | Agilent 7010D, Shimadzu GCMS-TQ8050 NX, Thermo TSQ 9610 | 500 000–900 000 PLN |
| Laboratory centrifuge | Hettich Rotina 380 R, Eppendorf 5810 R (≥4000 rcf) | 15 000–40 000 PLN |
| QuEChERS kits — extraction | Agilent Bond Elut QuEChERS EN, Restek Q-sep, pack of 50 pcs. | 800–1 500 PLN / 50 pcs. |
| QuEChERS kits — dSPE cleanup | Agilent dSPE 15 mL (PSA + MgSO₄ + C18), pack of 50 pcs. | 600–1 200 PLN / 50 pcs. |
| Homogenizer | Grindomix GM 200 (Retsch), Robot Coupe Blixer | 10 000–25 000 PLN |
| Shaker / vortex | IKA Vortex 3, Heidolph Multi Reax, SPEX SamplePrep | 2 000–8 000 PLN |
Reagents, media and consumables
| Reagent | CAS | Details |
|---|---|---|
| Acetonitrile LC-MS grade | 75-05-8 | Extraction solvent, 2.5 L for ~50 samples |
| Anhydrous magnesium sulfate MgSO₄ | 7487-88-9 | Drying salt — binds water, facilitates phase separation, 1 kg |
| Sodium chloride NaCl | 7647-14-5 | High-purity salt assisting phase partitioning |
| Sodium citrate dihydrate | 6132-04-3 | Citrate buffer (pH 5–5.5), in QuEChERS kits |
| PSA (Primary Secondary Amine) | 39393-37-0 | dSPE sorbent removing fatty acids, sugars, pigments |
| Pesticide standards (mixes) | — | Certified CRM mixes (Dr. Ehrenstorfer, AccuStandard), 50–200 analytes, in MeCN |
| Isotope-labeled internal standards | — | E.g., TPP (triphenyl phosphate), atrazine-d5, chlorpyrifos-d10 for recovery control |
| Formic acid LC-MS grade | 64-18-6 | Mobile phase additive for LC (0.1%), ESI+ ionization enhancement |
Health and safety (OHS)
- Acetonitrile — flammable (H225), toxic (H302, H312, H332). Work under fume hood.
- Pesticide standards — toxic, CMR. Use gloves, goggles, work under fume hood.
- Formic acid — corrosive (H314). Dose carefully.
- Food samples with pesticides — treat as potentially contaminated material.
- Acetonitrile waste — collect separately as halogenated/non-halogenated solvents.
- MS equipment — gases under pressure (He, N₂, Ar). Follow gas safety procedures.
Frequently asked questions
Which standard describes this test?
The test is performed according to PN-EN 15662:2018 — “Foods of plant origin — Multimethod for the determination of pesticide residues using GC- and LC-based analysis following acetonitrile extraction/partitioning and clean-up by dispersive SPE — QuEChERS method”.
How does this method work?
Sample (10 g homogenate) is extracted with 10 mL acetonitrile by vigorous shaking. Addition of extraction salts (4 g MgSO₄, 1 g NaCl, 1 g sodium citrate dihydrate, 0.
What is the measuring range and accuracy?
Number of analytes: 200–500 pesticides simultaneously; Limit of quantification (LOQ): 0.001–0.01 mg/kg; Recovery: 70–120% (SANTE/11312 acceptance criterion); Sample size: 10 g homogenate + 10 mL MeCN.
How long does the test take?
The times given for the individual stages add up to approximately 2 h 30 min–3 h 20 min. The procedure comprises 11 steps.
What equipment is required?
LC-MS/MS system, GC-MS/MS system, Laboratory centrifuge, QuEChERS kits — extraction, QuEChERS kits — dSPE cleanup, Homogenizer, Shaker / vortex. Indicative cost of the core instrument (LC-MS/MS system): 600 000–1 200 000 PLN.
Where is this test used?
Official control of pesticide residues in food (EC Reg. 396/2005); Monitoring of imported fruits and vegetables (RASFF program); Quality control of organic products (BIO); Testing of cereals, tea, spices, and processed food; HACCP systems and supplier control in food industry; GlobalGAP / IFS / BRC certification; Testing under EFSA monitoring programs.
What safety precautions apply?
Acetonitrile — flammable (H225), toxic (H302, H312, H332). Work under fume hood.; Pesticide standards — toxic, CMR. Use gloves, goggles, work under fume hood.; Formic acid — corrosive (H314). Dose carefully.; Food samples with pesticides — treat as potentially contaminated material.; Acetonitrile waste — collect separately as halogenated/non-halogenated solvents.; MS equipment — gases under pressure (He, N₂, Ar). Follow gas safety procedures.
Which laboratory can perform this test?
The test is performed by laboratories accredited to ISO/IEC 17025. On LabCoda you can find them by the standard number PN-EN 15662.