Zhenjiang Agricultural Products Quality Inspection and Testing Center, Zhenjiang, Jiangsu, China
Abstract: A rapid detection method for 45 pesticides and 8 metabolites (53 Pesticide Residues，Multi-Pesticide Residues) including fluazinam and chlorotoluron in strawberries was established using a multifunctional syringe filter and LC-MS/MS based on QuEChERS preprocessing technology. Strawberry samples were extracted with 1% acetonitrile containing acetic acid, purified and filtered using a QuEChERS syringe filter, and separated on a Waters BEH C18 column. Detection was performed using MRM mode on mass spectrometry. Results showed excellent linearity (R² > 0.99) for different target compounds at three fortification levels (0.05, 0.10, 0.20 mg/kg), with spike recoveries ranging from 75% to 114% and relative standard deviations (RSD) of 0.1% to 14.7%. The method is simple, rapid, accurate, reliable, requires minimal reagent use, and is suitable for multi-pesticide residues detection in strawberries.
QuEChERS syringe filter, Multi-Pesticide Residues, 53 Pesticide Residues, Multiple Pesticide Residues
In 2003, the United States Department of Agriculture’s Anastassiaeds. Metal. proposed the QuEChERS preprocessing method. Due to its advantages such as simplicity, speed, high recovery rates, accuracy, and precision, it has been widely used in pesticide residue detection technology.
This study employed a multifunctional syringe filter based on QuEChERS preprocessing technology, which simplifies and speeds up the purification and filtration of samples. Combined with LC-MS/MS, the study established a rapid multiresidue detection method suitable for 45 pesticides and 8 metabolites including fluazinam and chlorotoluron in strawberries.
1.Materials and Method
1.1 Instruments and Materials
- LC-MS spectrometer
- C18 column (1.7μm，1× 100 mm),
- Electronic balance
- Homogenizer
- High-speed refrigerated centrifuge
- HPLC-grade acetonitrile, HPLC-grade methanol, HPLC-grade formic acid, ultrapure water, analytical-grade acetic acid, analytical-grade sodium chloride
- QuEChERS Syringe Filter ( F-QuEChERS-AOAC 3201)
- 53 Pesticide standards, standards for multi-pesticide residues analysis
1.2 Sample Extraction and Purification
Accurately weigh 10 g of sample into a 50 mL centrifuge tube. Add 10 mL of 1% acetonitrile containing acetic acid. Homogenize at high speed for 1 minute, then add 4 g of sodium chloride. Vortex for 2 minutes, centrifuge at 7000 rpm for 5 minutes, and transfer 1 mL of the supernatant through a multifunctional syringe filter into a sample vial for analysis.
1.3 Instrument Conditions
Waters BEH C18，1.7μm，2.1×100 mm；
Temp.: 30 ℃；
Injection Sample Volume: 2μL；
Moble phase: 5 mmol/L
Ammonium acetate aqueous solution + 0.1% formic acid (aqueous phase) and methanol (organic phase)
Gradient elution, flow rate of 0.25 mL/min
Gradient elution program (5 mmol/L ammonium acetate aqueous solution + 0.1% formic acid : methanol)
| 0～2 min | 90%∶10% |
| 4 min | 50%∶50% |
| 6 min | 20%∶ 80% |
| 8～12 min | 10%∶90% |
| 13 min | 90%∶10% |
| 13～ 15 min | 90%∶10%。 |
MS: H-ESI; positive scan mode voltage 3,500 V, negative scan mode voltage 2,500 V; sheath gas (nitrogen) flow rate 45 Arb, auxiliary gas (nitrogen) flow rate 10 Arb; ion transfer tube temperature 350 ℃. Data collected in MRM mode for 53 compounds, with MS parameters for LC-MS/MS detection shown in Table 1.
Table 1: Mass Spectrometry Parameters for LC-MS/MS Detection of 53 Compounds (Simulating 53 pesticide residues)
| NO. | Compounds | Mode | Precursor ion (m·z-1) | Product ion (m·z-1) | Collision energy/V | RF lens voltage/V |
| 1 | Methamidophos | Positive | 141.97 | 94.11* 125 | 12 | 58 |
| 2 | Acetamiprid | Positive | 183.91 | 125 143.00* | 16 10 | 40 |
| 3 | Glyphosate | Positive | 213.94 | 155.00 182.93* | 15 10 | 65 |
| 4 | Thiamethoxam | Positive | 218.15 | 78.15 105.11* | 38 19 | 93 |
| 5 | Imidacloprid | Positive | 207.12 | 89.15* 132.11 | 10 | 43 |
| 6 | Thiamethoxam | Positive | 240.03 | 86.22 148.07* | 19 13 | 63 |
| 7 | Malathion | Positive | 163.3 | 88.11 106.11* 122.11 | 10 | 49 |
| 8 | Carbendazim | Positive | 192.09 | 132.05 160.00* | 29 17 | 129 |
| 9 | Thiacloprid | Positive | 291.94 | 132.00 180.99 211.06* | 20 21 | 85 |
| 10 | Imidacloprid | Positive | 256.03 | 175.04 209.00* | 17 14 | 107 |
| 11 | Citrinin | Positive | 345.04 | 143.11 239.11* | 27 12 | 92 |
| 12 | 3-Hydroxykynurenine | Positive | 238.12 | 163.05 181.13* 220.00 | 12 10 10 | 89 |
| 13 | Dinotefuran | Positive | 223 | 99.00 126.00* | 20 15 | 103 |
| 14 | Malathion | Positive | 229.94 | 125.07 198.88* | 20 10 | 82 |
| 15 | Thiamethoxam | Positive | 116.12 | 70.22 89.11* | 10 | 46 |
| 16 | DDT | Positive | 220.94 | 79.18 109.04* 145.00 | 25 17 12 | 116 |
| 17 | Carbaryl | Positive | 222.03 | 123.12 165.07* | 20 10 | 96 |
| 18 | Methomyl | Positive | 202.03 | 127.12 145.07* | 27 10 | 64 |
| 19 | Methidathion | Positive | 277.00 | 97.04 142.93 170.93 198.95* | 32 19 12 10 | 87 |
| 20 | Methamidophos | Positive | 292.94 | 143.00 171.00* 247.00 | 16 10 1 | 92 |
| 21 | Dimethoate | Positive | 312.00 | 236.00 270.00* | 25 18 | 102 |
| 22 | Chlorpyrifos | Positive | 248.06 | 129.04* 155.00 | 16 13 | 78 |
| 23 | Thiophanate-methyl | Positive | 317.97 | 105.12 133.07 160.00* | 43 35 10 | 90 |
| 24 | Methomyl | Positive | 200.12 | 107.11 183.00 | 24 23 | 174 |
| 25 | Difenoconazole | Positive | 294.13 | 70.29* 125.11 | 20 36 | 89 |
| 26 | Acetamiprid | Positive | 388.06 | 165.00 272.93 301.00* | 31 29 20 | 183 |
| 27 | Malathion | Positive | 331.03 | 284.93 127.11* | 10 | 74 |
| 28 | Triadimefon | Positive | 294.06 | 197.00* 225.00 | 15 12 | 127 |
| 29 | Triazophos | Positive | 314.12 | 119.12 162.07* | 31 17 | 150 |
| 30 | Fonofos | Positive | 386.91 | 258.84 281.88 350.88* | 38 31 10 | 142 |
| 31 | Flonicamid | Negative | 436.79 | 329.58* 332.50 | 14 16 | 123 |
| 32 | Fluazinam | Positive | 316.10 | 165.04* 247.06 | 27 17 | 109 |
| 33 | Fluensulfone | Negative | 418.88 | 261.89 313.89 382.89* | 28 19 10 | 130 |
| 34 | Carbaryl | Negative | 308.97 | 151.00 155.99 288.95* | 16 10 10 | 106 |
| 35 | Flusilazole | Negative | 450.91 | 243.88 281.95 414.89* | 48 27 15 | 173 |
| 36 | Fenoxycarb | Negative | 306.91 | 126.06 154.00* 270.93 | 25 10 10 | 107 |
| 37 | Buprofezin | Positive | 308.16 | 70.29* 125.04 | 22 36 | 93 |
| 38 | Dimethoate | Positive | 305.06 | 97.04 153.11 169.04* | 33 20 19 | 137 |
| 39 | Pyriproxyfen | Positive | 388.15 | 164.04 194.04* | 17 10 | 89 |
| 40 | Oxydemeton-methyl | Positive | 299.00 | 97.06 129. 12* | 17 10 | 84 |
| 41 | Imidacloprid | Positive | 375.94 | 265.89 308.03* | 16 10 | 122 |
| 42 | Malathion | Positive | 367.97 | 111.11 181.93* 321.96 | 37 13 10 | 114 |
| 43 | Methamidophos | Positive | 261.00 | 75.22* 198.88 | 10 | 58 |
| 44 | Propiconazole | Positive | 406.03 | 250.95* 336.88 | 23 16 | 126 |
| 45 | Methoxyfenozide | Positive | 404.09 | 329.00* 344.06 372.00 | 30 24 10 | 131 |
| 46 | Oxymatrine | Positive | 409.16 | 186.06 206.04* | 17 13 | 96 |
| 47 | Amitraz benzoate | Positive | 886.70 | 82.22 158.11* 868.44 | 47 34 19 | 298 |
| 48 | Chlorpyrifos | Positive | 372.91 | 302.75* 344.75 | 17 12 | 133 |
| 49 | DDT | Positive | 349.79 | 97.05 197.88* | 28 17 | 130 |
| 50 | Deltamethrin | Positive | 282.09 | 148.05 194.00 212.00* | 27 17 10 | 79 |
| 51 | Flupyrimin | Positive | 540.00 | 158.05 346.96 382.82* | 19 42 19 | 181 |
| 52 | Abamectin | Positive | 365.06 | 147.11 309.00* | 23 10 | 78 |
| 53 | Avermectin | Positive | 895.46 | 449.21 751.26* | 43 39 | 296 |
2 Results and Analysis
2.1 Selection of Extraction Solvent
In blank strawberry samples, pesticide standard solutions of known concentrations were added, subjected to preprocessing, and then analyzed. The mass concentration of compounds was plotted on the x-axis against the peak area of the quantitative ion pair response on the y-axis to construct calibration curves. The results indicated that all 53 compounds exhibited excellent linearity, with correlation coefficients greater than 0.99. The concentration corresponding to three times the signal-to-noise ratio was determined as the method detection limit (as shown in Table 2).
Compared to conventional QuEChERS preprocessing, the QuEChERS syringe filter integrates the purification and filtration processes of QuEChERS preprocessing into one step, achieving a streamlined approach that is simpler, quicker, and effectively enhances preprocessing efficiency.
QuEChERS Syringe Filter containing PSA 50mg and MgSO4 150mg
Table 2: Linear Regression Equations and Detection Limits of 53 Compounds
| No | Compounds | Retention time/min | Lnear range /（mg·kg-1） | Linear regression equation | R2 | Detection limit /（mg·kg-1） |
| 1 | Methamidophos | 2.14 | 0.002～0.200 | y= 1 051x-1 325 | 0.9984 | 0.002 |
| 2 | Acetamiprid | 3.03 | 0.005～0.200 | y=999x+1 218 | 0.9989 | 0.005 |
| 3 | Glyphosate | 4.11 | 0.002～0.200 | y= 1 428x-1 052 | 0.9994 | 0.002 |
| 4 | Thiamethoxam | 4.30 | 0.010～0.200 | y= 194.7x-624.2 | 0.9988 | 0.010 |
| 5 | Imidacloprid | 5.10 | 0.010～0.200 | y=324.9x-3 068 | 0.9967 | 0.010 |
| 6 | Thiamethoxam | 5.48 | 0.002～0.200 | y= 1 696x+4 934 | 0.9975 | 0.002 |
| 7 | Malathion | 5.84 | 0.002～0.200 | y=702.3x+453.3 | 0.9977 | 0.002 |
| 8 | Carbendazim | 5.99 | 0.002～0.200 | y=977.8x-4 414 | 0.9977 | 0.002 |
| 9 | Thiacloprid | 6.03 | 0.001～0.200 | y=6 627x+32 470 | 0.9954 | 0.001 |
| 10 | Imidacloprid | 6.48 | 0.001～0.200 | y=2 333x+10 520 | 0.9989 | 0.001 |
| 11 | Citrinin | 6.71 | 0.020～0.200 | y=49.4x-622 | 0.9999 | 0.020 |
| 12 | 3-Hydroxykynurenine | 6.71 | 0.001～0.200 | y= 1 836x+5 092 | 0.9961 | 0.001 |
| 13 | Dinotefuran | 6.75 | 0.001～0.200 | y=8 176x+27 930 | 0.9973 | 0.001 |
| 14 | Malathion | 6.77 | 0.001～0.200 | y=6 110x+5 604 | 0.9992 | 0.001 |
| 15 | Thiamethoxam | 7.31 | 0.002～0.200 | y=3 290x-8 324 | 0.9959 | 0.002 |
| 16 | DDT | 7.66 | 0.002～0.200 | y=2 203x+3 681 | 0.9984 | 0.002 |
| 17 | Carbaryl | 7.69 | 0.001～0.200 | y=4 656x+13 140 | 0.9980 | 0.001 |
| 18 | Methomyl | 7.87 | 0.001～0.200 | y=3 664x+1 409 | 0.9986 | 0.001 |
| 19 | Methidathion | 8.03 | 0.001～0.200 | y=4 823x+2 562 | 0.9982 | 0.001 |
| 20 | Methamidophos | 8.11 | 0.005～0.200 | y=766.3x+2 719 | 0.9967 | 0.005 |
| 21 | Dimethoate | 8.18 | 0.005～0.200 | y=21.02x+555.2 | 0.9969 | 0.005 |
| 22 | Chlorpyrifos | 8.29 | 0.001～0.200 | y=26 820x+151 800 | 0.9956 | 0.001 |
| 23 | Thiophanate-methyl | 8.40 | 0.001～0.200 | y=8 266x+41 130 | 0.9952 | 0.001 |
| 24 | Methomyl | 8.54 | 0.005～0.200 | y=667.8x+9 015 | 0.9997 | 0.005 |
| 25 | Difenoconazole | 8.69 | 0.001～0.200 | y= 13 700x+644 500 | 0.9970 | 0.001 |
| 26 | Acetamiprid | 8.70 | 0.001～0.200 | y= 14 530x+52 340 | 0.9970 | 0.001 |
| 27 | Malathion | 8.70 | 0.001～0.200 | y=3 081x+7 849 | 0.9966 | 0.001 |
| 28 | Triadimefon | 8.77 | 0.001～0.200 | y=2 293x+9 925 | 0.9957 | 0.001 |
| 29 | Triazophos | 8.83 | 0.001～0.200 | y=7 062x-2 169 | 0.9975 | 0.001 |
| 30 | Fonofos | 9.02 | 0.002～0.200 | y=932.6x-2 997 | 0.9983 | 0.002 |
| 31 | Flonicamid | 9.13 | 0.002～0.200 | y= 1 264x-291.2 | 0.9976 | 0.002 |
| 32 | Fluazinam | 9.14 | 0.001～0.200 | y= 19 070x+96 730 | 0.9970 | 0.001 |
| 33 | Fluensulfone | 9.22 | 0.001～0.200 | y=8 332x-24 330 | 0.9975 | 0.001 |
| 34 | Carbaryl | 9.22 | 0.010～0.200 | y=94.43x-305.3 | 0.9957 | 0.010 |
| 35 | Flusilazole | 9.36 | 0.001～0.200 | y=8 325x-1 529 | 0.9985 | 0.001 |
| 36 | Fenoxycarb | 9.41 | 0.020～0.200 | y= 142.9x+2 219 | 0.9982 | 0.020 |
| 37 | Buprofezin | 9.42 | 0.001～0.200 | y= 14 330x+85 920 | 0.9958 | 0.001 |
| 38 | Dimethoate | 9.48 | 0.001～0.200 | y=29 710x+23 010 | 0.9986 | 0.001 |
| 39 | Pyriproxyfen | 9.51 | 0.001～0.200 | y= 16 950x+5 987 | 0.9972 | 0.001 |
| 40 | Oxydemeton-methyl | 9.54 | 0.001～0.200 | y=3 787x+1 492 | 0.9979 | 0.001 |
| 41 | Imidacloprid | 9.60 | 0.001～0.200 | y= 1 403x+3 442 | 0.9993 | 0.001 |
| 42 | Malathion | 9.65 | 0.001～0.200 | y=3 664x+8 460 | 0.9961 | 0.001 |
| 43 | Methamidophos | 9.72 | 0.005～0.200 | y= 1 670x+680.3 | 0.9975 | 0.005 |
| 44 | Propiconazole | 9.80 | 0.001～0.200 | y=33 750x+72 370 | 0.9978 | 0.001 |
| 45 | Methoxyfenozide | 9.81 | 0.001～0.200 | y=7 851x+4 174 | 0.9975 | 0.001 |
| 46 | Oxymatrine | 9.81 | 0.001～0.200 | y= 16 120x+21 870 | 0.9986 | 0.001 |
| 47 | Amitraz benzoate | 10.09 | 0.002～0.200 | y=4 689x+5 001 | 0.9990 | 0.002 |
| 48 | Chlorpyrifos | 10.20 | 0.001～0.200 | y= 10 630x-5 436 | 0.9970 | 0.001 |
| 49 | DDT | 10.72 | 0.002～0.200 | y= 1 776x-2 236 | 0.9955 | 0.002 |
| 50 | Deltamethrin | 10.83 | 0.001～0.200 | y=6 603x-20 390 | 0.9986 | 0.001 |
| 51 | Flupyrimin | 11.28 | 0.001～0.200 | y=4 782x-2 798 | 0.9979 | 0.001 |
| 52 | Abamectin | 11.53 | 0.001～0.200 | y=34 420x+19 580 | 0.9981 | 0.001 |
| 53 | Avermectin | 11.99 | 0.010～0.200 | y=41x+341.4 | 0.9963 | 0.010 |
2.4 Accuracy and Precision of the Method
In blank strawberry samples, pesticide standard solutions of known concentrations were separately added at levels of 0.05, 0.10, and 0.20 mg/kg. The results showed that at these addition levels, the recovery rates ranged from 75% to 114%, with relative standard deviations (RSD) ranging from 0.1% to 14.7% (as shown in Table 3).
Table 3: Recovery Rates and Relative Standard Deviations (n=6) of 53 Pesticides in Strawberries
| No. | Compounds | Spiked concentration /（mg·kg-1） | Recovery Rate/% | RSD/% |
| 1 | Methamidophos | 0.05、0.10、0.20 | 76～90 | 1.9～4.5 |
| 2 | Acetamiprid | 0.05、0.10、0.20 | 75～98 | 5.0～14.4 |
| 3 | Glyphosate | 0.05、0.10、0.20 | 76～90 | 0.9～6.3 |
| 4 | Thiamethoxam | 0.05、0.10、0.20 | 92～102 | 2.0～6.4 |
| 5 | Imidacloprid | 0.05、0.10、0.20 | 75～110 | 9.6～12.0 |
| 6 | Thiamethoxam | 0.05、0.10、0.20 | 90～100 | 2. 1～6.0 |
| 7 | Malathion | 0.05、0.10、0.20 | 90～98 | 3.2～14.7 |
| 8 | Carbendazim | 0.05、0.10、0.20 | 95～106 | 1.6～9.5 |
| 9 | Thiacloprid | 0.05、0.10、0.20 | 98～102 | 3. 1～3.7 |
| 10 | Imidacloprid | 0.05、0.10、0.20 | 95～104 | 1.6～4.8 |
| 11 | Citrinin | 0.05、0.10、0.20 | 98～113 | 7.8～10.7 |
| 12 | 3-Hydroxykynurenine | 0.05、0.10、0.20 | 94～100 | 0.2～1.4 |
| 13 | Dinotefuran | 0.05、0.10、0.20 | 96～104 | 0.3～4.5 |
| 14 | Malathion | 0.05、0.10、0.20 | 98～104 | 4.6～7.0 |
| 15 | Thiamethoxam | 0.05、0.10、0.20 | 98～104 | 3.5～8.4 |
| 16 | DDT | 0.05、0.10、0.20 | 98～104 | 0.9～5.8 |
| 17 | Carbaryl | 0.05、0.10、0.20 | 89～100 | 2.3～4.2 |
| 18 | Methomyl | 0.05、0.10、0.20 | 98～104 | 3.7～5.2 |
| 19 | Methidathion | 0.05、0.10、0.20 | 96～100 | 2.8～5.4 |
| 20 | Methamidophos | 0.05、0.10、0.20 | 94～98 | 2.6～14.5 |
| 21 | Dimethoate | 0.05、0.10、0.20 | 100～114 | 3.2～6.7 |
| 22 | Chlorpyrifos | 0.05、0.10、0.20 | 95～108 | 0. 1～7.0 |
| 23 | Thiophanate-methyl | 0.05、0.10、0.20 | 94～98 | 0.6～1.8 |
| 24 | Methomyl | 0.05、0.10、0.20 | 84～102 | 11.0～14.5 |
| 25 | Difenoconazole | 0.05、0.10、0.20 | 95～108 | 1.0～2.3 |
| 26 | Acetamiprid | 0.05、0.10、0.20 | 91～96 | 0.4～3.1 |
| 27 | Malathion | 0.05、0.10、0.20 | 94～98 | 1.8～4.5 |
| 28 | Triadimefon | 0.05、0.10、0.20 | 97～100 | 3.2～5.0 |
| 29 | Triazophos | 0.05、0.10、0.20 | 98～104 | 1.5～7.4 |
| 30 | Fonofos | 0.05、0.10、0.20 | 96～104 | 12.7～14.3 |
| 31 | Flonicamid | 0.05、0.10、0.20 | 98～104 | 0.4～4.1 |
| 32 | Fluazinam | 0.05、0.10、0.20 | 95～102 | 0. 1～4.7 |
| 33 | Fluensulfone | 0.05、0.10、0.20 | 96～104 | 1. 1～5.1 |
| 34 | Carbaryl | 0.05、0.10、0.20 | 96～106 | 1. 1～5.2 |
| 35 | Flusilazole | 0.05、0.10、0.20 | 94～100 | 0.7～3.5 |
| 36 | Fenoxycarb | 0.05、0.10、0.20 | 76～98 | 0. 1～4.5 |
| 37 | Buprofezin | 0.05、0.10、0.20 | 95～98 | 0. 1～4.7 |
| 38 | Dimethoate | 0.05、0.10、0.20 | 100～106 | 4.6～9.2 |
| 39 | Pyriproxyfen | 0.05、0.10、0.20 | 91～98 | 0.8～4.6 |
| 40 | Oxydemeton-methyl | 0.05、0.10、0.20 | 90～98 | 7.4～14.1 |
| 41 | Imidacloprid | 0.05、0.10、0.20 | 94～100 | 7.0～10.2 |
| 42 | Malathion | 0.05、0.10、0.20 | 100～104 | 2.6～6.0 |
| 43 | Methamidophos | 0.05、0.10、0.20 | 100～104 | 1.2～7.4 |
| 44 | Propiconazole | 0.05、0.10、0.20 | 92～102 | 1.6～2.0 |
| 45 | Methoxyfenozide | 0.05、0.10、0.20 | 91～100 | 1.5～8.1 |
| 46 | Oxymatrine | 0.05、0.10、0.20 | 97～104 | 1.2～1.8 |
| 47 | Amitraz benzoate | 0.05、0.10、0.20 | 92～96 | 0.2～5.7 |
| 48 | Chlorpyrifos | 0.05、0.10、0.20 | 100～104 | 0.5～2.7 |
| 49 | DDT | 0.05、0.10、0.20 | 94～104 | 2.6～8.4 |
| 50 | Deltamethrin | 0.05、0.10、0.20 | 90～100 | 1.6～6.0 |
| 51 | Flupyrimin | 0.05、0.10、0.20 | 94～100 | 0.8～3.9 |
| 52 | Abamectin | 0.05、0.10、0.20 | 96～100 | 0.6～1.5 |
| 53 | Avermectin | 0.05、0.10、0.20 | 108～114 | 0.3～12.6 |
3 Conclusion
This study employed a multifunctional syringe filter based on QuEChERS preprocessing technology, integrating purification and filtration into one unit. Combined with liquid chromatography-tandem mass spectrometry, a rapid multi-residue detection method was established for 45 pesticides and 8 metabolites in strawberries, including fluazinam and chlorpyrifos. The method offers a simple, fast, accurate, and reliable preprocessing step, providing an efficient analytical approach for screening and confirming pesticide residues in strawberries.
References: Omitted
