Rapid Multiresidue Pesticide Detection in Food

Application Note Environmental Author Brooke C. Reaser Agilent Technologies, Inc. Abstract Multiresidue pesticide analysis has become one of the most difficult but important analytical challenges for those using gas chromatography and mass spectrometry. The Agilent 8890 gas chromatograph (GC) coupled with the Agilent 7010 triple quadrupole mass spectrometer (GC/TQ) with a high efficiency source 2.0 (HES 2.0) upgrade is an analytically accurate, robust, and reproducible instrument for multiresidue pesticide analysis of complex samples. The analysis of 190 pesticides in a spinach extract was conducted using an Agilent QuEChERS extraction kit across 800 injections. Only GC inlet maintenance was required over the duration of the injections. The instrument configuration that enabled robust performance included a multimode inlet, a mid-column backflushing configuration, and the HES 2.0. No degradation of the analytical method, sensitivity, or instrument performance occurred, allowing for the high-throughput, accurate, robust, and sensitive detection of pesticides in spinach. Enhanced Longevity and Revolutionized Robustness for the Sensitive Detection of 190 Pesticides over 800 Injections 2 Introduction Multiresidue pesticide analysis remains an important analytical challenge for food safety.1-7 Pesticides used to improve crop yield can end up in the final product, raising concerns for consumer safety. As a result, multiple governing bodies worldwide have published requirements for the maximum legal residue limit (MRL) or tolerance for pesticides allowed in a product. However, the number of pesticides used in food products continues to grow as novel chemicals are introduced, which in turn increases the complexity of the multiresidue pesticide analysis. For especially difficult matrices, QuEChERS, which stands for quick, easy, cheap, effective, rugged, and safe, has become widely accepted as a sample preparation technique for multiresidue pesticide analysis.1 Agilent QuEChERS extraction kits provide prepackaged dispersive and extraction products, extraction salts, and ceramic homogenizers in easy-to-use kits. The kits are ready-made for various methods, including methods of the Association of Official Agricultural Chemists (AOAC)2 and European Standard (EN).3 QuEChERS extracts of food commodities can be analyzed by either GC or high performance liquid chromatography (HPLC) combined with a mass spectrometer (MS) or tandem mass spectrometers (MS/MS).4,5 Depending on the extent of sample cleanup and the food commodity being analyzed, QuEChERS extracts can cause contamination of the instrument, resulting in poor data quality.6 This contamination can exhibit as loss of sensitivity, retention time shifting, poor peak shape, and more. Regular maintenance of the instrument, including GC inlet maintenance, GC column trimming, and ion source cleaning, is required to ensure the robustness and accuracy of the method results. Backflushing is one of the key practices in which GC/MS/MS analyses of complex matrices can be improved.7 Backflushing refers to the reversing of flows in the capillary column so that unwanted matrix components are flushed out of the GC split vent instead of proceeding to the detector. Backflushing can provide improved method robustness and help minimize the required maintenance of the mass spectrometer. Agilent has introduced the new HES 2.0 ion source as part of the 7010D triple quadrupole mass spectrometer (TQ), and it is also available as an upgrade to 7010A/B/C GC/TQ instruments. The HES 2.0 ion source provides improved system robustness, allowing the analysis of hundreds of injections of pesticides in food matrices with only GC maintenance and ion source cleaning necessary. The HES 2.0 delivers the same unparalleled analytical sensitivity for ultratrace-level analysis as the original HES. Multiresidue pesticide analysis in spinach extract was carried out using a 7010B GC/TQ upgraded with the HES 2.0. Matrix-matched standards were used to analyze and quantify over 400 injections of baby spinach extract spiked with 50 ppb of multiresidue standards, demonstrating both method and instrument robustness. The multimode inlet (MMI) and backflushing between two 15 m columns allowed for minimal downtime for GC inlet maintenance. Sensitivity and quantitative accuracy were maintained without any maintenance performed on the mass spectrometer. Experimental GC/TQ analysis An 8890 GC with a 7010B TQ system upgraded with the HES 2.0 was used for analysis. The instrument and method were configured as outlined in a previous application note7 , as shown in Figure 1. Agilent 7010 with HES 2.0 PSD (helium) Agilent 8890 GC Liquid Injector Multimode inlet (helium) HES 2.0 Agilent HP-5ms UI 15 m, 0.25 × 0.25 Figure 1. The Agilent 8890/7010B GC/TQ system upgraded with the HES 2.0 and system configuration. 3 The GC was equipped with an Agilent 7650A automatic liquid sampler (ALS) and 50-position tray. The GC used an MMI to achieve a temperature-programmed splitless injection. Mid-column backflush was carried out using an Agilent Purged Ultimate Union (PUU) installed between two identical 15 m columns; the 8890 GC pneumatic switching device (PSD) module allowed for fewer occurrences of regular maintenance. The method parameters are listed in Table 1. Table 1. Agilent 8890 GC and Agilent 7010B upgraded with the HES 2.0 ion source conditions for pesticide analysis. GC Instrument Agilent 8890 with Fast Oven, Auto Injector and Tray Inlet Multimode Inlet (MMI) Mode Splitless Purge Flow to Split Vent 15 mL/min at 0.75 min Septum Purge Flow 3 mL/min Septum Purge Flow Mode Switched Injection Volume 1.0 µL Injection Type Standard L1 Air Gap 0.1 µL Gas Saver Off Inlet Temperature 60 °C for 0.1 min, then to 280 °C at 600 °C/min Postrun Inlet Temperature 310 °C Postrun Total Flow 25 mL/min Carrier Gas Helium Inlet Liner Agilent Ultra Inert 2 mm dimpled liner (p/n 5190‑2297) Oven Initial Oven Temperature 60 °C Initial Oven Hold 1 min Ramp Rate 1 40 °C/min Final Temperature 1 170 °C Final Hold 1 0 min Ramp Rate 2 10 °C/min Final Temperature 2 310 °C Final Hold 2 3 min Total Run Time 20.75 min Postrun Time (Backflushing) 1.5 min Equilibration Time 3 min Column 1 Type Agilent HP-5ms UI (p/n 19091S-431UI) Length 15 m Diameter 0.25 mm Film Thickness 0.25 µm Control Mode Constant flow Flow 1.00 mL/min Inlet Connection Multimode inlet (MMI) Outlet Connection PSD (PUU) PSD Purge Flow 5 mL/min Postrun Flow (Backflushing) –7.873 mL/min Column 2 Type Agilent HP-5ms UI (p/n 19091S-431UI) Length 15 m Diameter 0.25 mm Film Thickness 0.25 µm Control Mode Constant flow Flow 1.200 mL/min Inlet Connection PSD (PUU) Outlet Connection MSD Postrun Flow (Backflushing) 8.202 mL/min MSD Model Agilent 7010B Source Agilent HES 2.0 Vacuum Pump Performance turbo Tune File Atunes.eihs.tune.xml Solvent Delay 3 min Quad Temp (MS1 and MS2) 150 °C Source Temperature 280 °C Mode dMRM or Scan He Quench Gas 4 mL/min N2 Collision Gas 1.5 mL/min MRM Statistics Total MRMs (dMRM mode) 552 Minimum Dwell Time (ms) 2.63 Minimum Cycle Time (ms) 82.42 Maximum Concurrent MRMs 48 EM Voltage Gain Mode 10 4 The Agilent Pesticide and Environmental Pollutant (P&EP) database (P&EP 4, part number G9250AA) was used to easily and rapidly create the dynamic multiple reaction monitoring (dMRM) method. This method, which enabled the analysis of 190 pesticides with a total of 552 MRMs, resulted in a maximum of 48 concurrent MRMs, as shown in Figure 2. QuEChERS sample preparation The sample preparation procedure is summarized in Figure 3. A bag of frozen organic baby spinach was homogenized using a spice grinder. Then, eight replicates were prepared. For each replicate, 15 g of the homogenized spinach were weighed into a 50 mL test tube. Then, two of the replicates were designated as samples, while the remaining six were designated for pooled matrix-matched standards. Fifteen microliters of the internal standard mixture (part number 5190-0502) diluted to 50 ng/µL was added to the two spinach samples. To all eight replicates, 15 mL of 1% acetic acid in acetonitrile was added and the mixture was vortexed until well mixed. To each Figure 2. Concurrent MRMs versus retention time. Retention time (min) Concurrent MRMs 0 4 8 12 16 20 24 28 32 36 40 44 48 52 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 Figure 3. Sample preparation workflow. QuEChERS extraction kit Agilent QuEChERS dispersion kit 15 g of spinach + 15 mL of ACN with 1% AA, vortex Take 8 mL supernatant Shake and centrifuge Shake and centrifuge Dilute, spike, and prepare in-vial Sample analysis on GC/TQ 5 50 mL tube, the salt packet and two homogenizers from the QuEChERS kit (part number 5982-5755) were added for extraction. These were shaken for 1 minute, then centrifuged at 4,000 rpm with a maximum radius of 17.4 cm for 5 minutes. For the samples and the pooled standards, 8 mL of the supernatant was transferred to a tube with salt for dispersion using the QuEChERS kit (part number 5982-5058). These were shaken for 30 seconds then centrifuged as before for 5 minutes. The supernatant for each of the samples was removed and placed in an amber glass vial. For the pooled standards, the supernatant of all replicates was removed and mixed in a large amber jar for standard preparation. Standard preparation The multiresidue matrix-matched standards were created from the FDA analytical reference standards kit (part number PSM-101). Mixes A, B, C, D, E, L, M, N, O, and P from the PSM-101 pesticides mix were combined to create a 10 ppm stock standard of 190 pesticide residues. The stock solution was then diluted in acetonitrile down to the following nominal concentrations: 1,000, 100, 10, and 1 ppb. In a GC vial, the standards were combined with the spinach extract. The internal standard mixture of parathion-d10 and alpha-BHC-d6 , and acetonitrile were combined until the nominal concentration of the internal standard was 50 ppb and the nominal concentrations of the matrix-matched standards in a total volume of 1,500 µL were as follows: 0.1, 0.5, 1, 5, 10, 50, 100, 253.3, 500, and 1,000 ppb. Extra vials of the 50-ppb matrix-matched standard were made for quantification to test robustness. The samples were diluted by a factor of three in the vials to match the matrix concentration in the standards. This 3x dilution factor was determined by analyzing the matrix alone in full scan mode as described in a previous application note7 to ensure that the instrument was not overloaded or saturated by the matrix. Vials with 250 µL glass inserts were used with 100 µL of each standard or sample in-vial for GC analysis. Sequence Each sequence included 102 injections of spinach extract, either as a sample or matrix-matched standard. Additional injections of blank acetonitrile were used to evaluate system cleanliness by ensuring no analyte carryover or additional background contamination. A representative MRM chromatogram of the 50-ppb matrix-matched standards in spinach extract is shown in Figure 4A with a zoomed in portion shown in Figure 4B. The sequence included: – Matrix-matched calibration curve (10 pts) – Two spinach samples – Matrix-matched calibration curve (10 pts) – Matrix-matched standards (50 ppb) × 60 times – Matrix-matched calibration curve (10 pts) × 2 times, each standard in duplicate Figure 4. A representative chromatogram (A) and a zoomed in portion of the chromatogram (B). ×108 A Acquisition time (min) Counts 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 ×107 B Acquisition time (min) Counts 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 6 To achieve more than 400 injections of the 50 ppb matrix-matched standard, seven sequences were run for a total of 819 injections, of which 714 were spinach matrix injections. After each sequence, the GC inlet liner and septum were changed, and the 5 µL syringe was changed as necessary. Also, the GC vials were refreshed with samples and standards that had been stored in the freezer. No additional instrument maintenance was performed. Results and discussion Of the 190 pesticide residues analyzed by GC/TQ, 114 were selected for further study based on their analytical response and performance. These 114 residues were chosen because their calibration curves were either linear or quadratic throughout the seven sequences. These curves did not require extensive analyst intervention, such as manual integration, and had calibration curves that encompassed the 50 ppb point so that the 50 ppb matrix-matched standards for robustness could be calculated as samples. Any points on the calibration curve that had signal-to-noise (S/N) < 3, were interfered with by contaminants, or had accuracy greater than or equal to ± 25% were excluded (≥ ± 25%). A table summarizing these residues can be found at the end of the application note in Table 2. Many of the pesticide residues could accurately be quantified down to 0.5 or 0.1 ppb while maintaining S/N > 10 and quantification accuracy of < 25%. For example, Figures 5A, 5B, and 5C show the 0.1 ppb peak, corresponding qualifiers, and calibration curve of DCPA, respectively. The data are defined well by a quadratic calibration curve over the calibration range 0.1 to 1,000 ppb through four orders of magnitude. DCPA has many MRLs as defined by the US FDA down to 50 ppb in various fruits and vegetables. Figure 5. Integrated peak (A) and qualifiers (B) of the 0.1 ppb peak of DCPA as well as the full calibration curve (C). ×103 ×102 A B ×10 C 1 Acquisition time (min) Counts + MRM CID at 25.0 (298.9 & 221.0) 10.26 10.28 10.30 10.32 10.34 10.36 10.38 10.40 10.42 10.44 Acquisition time (min) 10.26 10.28 10.30 10.32 10.34 10.36 10.38 10.40 10.42 10.44 -0.2 0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 10.325 min -0.2 -0.1 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 298.9 & 221.0 300.9 & 223.0 331.8 & 300.9 Ratio = 89.2 (95.1%) Ratio = 42.0 (97.0%) DCPA Relative concentration 0 1 2 3 4 5 6 7 8 9 10 -0.2 0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6 y = -0.013350x2 + 2.835571x + 0.001611 R2 = 0.99899365 R = 0.99969055 Weight: 1/x Relative abundance (%) Relative responses 7 Figures 6A and 6B show the chlorpyrifos 0.5 ppb peak and qualifiers (respectively), while Figure 6C shows the corresponding calibration curve. The curve is linear through 3.5 orders of magnitude and chlorpyrifos has MRLs in various food commodities, the lowest of which is 0.01 ppm in food items such as egg, fig, grape, and apple. Figure 6. Integrated peak (A), qualifiers (B) of the 0.5 ppb peak of chlorpyrifos as well as the full calibration curve (C). ×104 ×102 A B ×10 C 1 Acquisition time (min) Counts Relative concentration Relative abundance (%) Relative responses -0.2 -0.1 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 196.9 & 169.0 198.9 & 171.0 313.8 & 257.8 Ratio = 103.0 (108.4%) Ratio = 43.1 (98.7%) + MRM CID at 15.0 (196.9 & 169.0) 10.16 10.18 10.20 10.22 10.24 10.26 10.28 10.30 10.32 Acquisition time (min) 10.16 10.18 10.20 10.22 10.24 10.26 10.28 10.30 10.32 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 10.220 min Chlorpyrifos 0 1 2 3 4 5 6 7 8 9 10 -0.2 0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 y = 2.182005x + 0.002352 R2 = 0.99501738 R = 0.99950640 Weight: 1/x2 8 In terms of spinach MRLs, Figures 7, 8, and 9 provide three examples. Figure 7 shows the results for bifenthrin, which is quadratic through 3.5 orders of magnitude down to 0.5 ppb and has an MRL of 0.2 ppm in spinach. Diazinon, linear through 3.5 orders of magnitude down to 0.5 ppb, is shown in Figure 8, with an MRL in spinach of 0.7 ppm. Figure 7. Integrated peak (A), qualifiers (B) of the 0.5 ppb peak of bifenthrin as well as the full calibration curve (C). ×104 ×102 A B ×10 C 2 Acquisition time (min) Counts Relative concentration Relative abundance (%) Relative responses Bifenthrin 0 1 2 3 4 5 6 7 8 9 10 -0.2 0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 y = 0.459107x2 + 18.988674x + 0.012908 R2 = 0.99465789 R = 0.99640909 Weight: 1/x2 + MRM CID at 25.0 (181.2 & 165.2) 14.14 14.16 14.18 14.20 14.22 14.24 14.26 14.28 14.30 14.32 Acquisition time (min) 14.14 14.16 14.18 14.20 14.22 14.24 14.26 14.28 14.30 14.32 2 3 4 5 6 7 8 14.202 min -0.2 -0.1 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 181.2 & 165.2 181.2 & 166.2 166.2 & 165.2 Ratio = 87.4 (109.7%) Ratio = 52.5 (107.2%) 9 Figure 8. Integrated peak (A), qualifiers (B) of the 0.5 ppb peak for diazinon as well as the full calibration curve (C). ×103 ×102 A B C Acquisition time (min) Counts Relative concentration Relative abundance (%) Relative responses Diazinon 0 1 2 3 4 5 6 7 8 9 10 0 1 2 3 4 5 6 7 8 y = 0.638177x – 3.640200E-004 R2 = 0.98721937 R = 0.99294761 Weight: 1/x2 -0.1 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 137.1 & 84.0 199.1 & 93.0 Ratio = 64.7 (96.5%) + MRM CID at 10.0 (137.1 & 84.0) 8.44 8.46 8.48 8.50 8.52 8.54 8.56 8.58 8.60 8.62 Acquisition time (min) 8.44 8.46 8.48 8.50 8.52 8.54 8.56 8.58 8.60 8.62 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 8.523 min 10 Lastly, boscalid is shown in Figure 9 with an MRL of 1 ppb; it is easily defined by a quadratic curve with four orders of magnitude down to 0.1 ppb. In the spinach sample, all three residues fell below the limit of quantification (LOQ) of the analytical method, and below their respective spinach MRLs. In the spinach samples, both boscalid and bifenthrin fell below the limit of detection (LOD) as no peak was detected for either residue. However, a small amount of diazinon was detected that was not present in the solvent blank. However, the area of the peak fell well below the LOQ and had an S/N very close to 3, and therefore approached or fell below the LOD. ×103 ×102 ×102 A B C Acquisition time (min) Counts Relative concentration Relative abundance (%) Relative responses -0.1 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 140.0 & 112.0 140.0 & 76.0 111.9 & 76.0 Ratio = 87.0 (104.4%) Ratio = 32.9 (99.3%) + MRM CID at 10.0 (140.0 & 112.0) 16.84 16.86 16.88 16.90 16.92 16.94 16.96 16.98 17.00 17.02 Acquisition time (min) 16.84 16.86 16.88 16.90 16.92 16.94 16.96 16.98 17.00 17.02 0 1 2 3 4 5 6 7 Boscalid 16.909 min 0 1 2 3 4 5 6 7 8 9 10 0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 y = 0.635140x2 + 8.900401x + 0.002796 R2 = 0.97434891 R = 0.99281390 Weight: 1/x2 Figure 9. Integrated peak (A), qualifiers(B) of 0.1 ppb peak of boscalid as well as the full calibration curve (C). 11 The innovative HES 2.0 source enabled enhanced response stability for the analyzed pesticides over 400 replicate injections of the matrix-matched calibration standard at 50 ppb analyzed within a sequence with over 800 total injections. Figure 10 shows the 400 replicates of the 50 ppb matrix-matched standard, calculated as samples from the corresponding calibration curves across six sequences. The X-axis on the top corresponds to the number of injections of just the 50 ppb matrix-matched standard for robustness. The lower X-axis corresponds to the total injection number of spinach QuEChERS matrix, and therefore excludes blank injections. The concentration in ppb versus injection number plot shows how robust and accurate the analysis was. The results showed all but one point falling within ± 20% error, the usual % error given by GC/TQ data, and most points well within ± 10% of the actual. The %RSD for 400 replicates of all 114 residues are summarized in Table 2, with nearly 80% of the 114 residues having %RSD < 10%, and only five having %RSD above 20%. The robustness of the analysis and the instrument is clearly shown, with only inlet maintenance required between sequences and no further maintenance of the instrument needed. Figure 10. Calculated concentration of pesticides in 50 ppb matrix-matched standard over the course of 714 injections of spinach QuEChERS extract. 0 50 100 150 200 250 300 350 400 30 35 40 45 50 55 60 65 70 23 73 165 257 349 441 533 583 675 Adjusted 50 ppb spiked standard injection number ppb QuEChERS injection number Parathion BHC-alpha (benzene hexachloride) Pentachlorobenzonitrile Pentachlorothioanisole Fenthion 12 Table 2. Summary of 114 residues, including calibration range, calibration curve fit, and %RSD over the 400 injections of 50 ppb matrix-matched standard injections for robustness. Those results with %RSD > 20% are highlighted in red. Name Retention Time (minutes) Min Cal (ppb) Max Cal (ppb) Curve Fit Curve Weight %RSD Ethiolate 4.609 0.5 1,000 Linear 1/x2 7.6 Dichlorvos 4.826 0.5 1,000 Quadratic 1/x 10.4 Nicotine 5.424 0.5 1,000 Linear 1/x2 11.9 Biphenyl 5.615 1 1,000 Linear 1/x2 6.2 2-Phenylphenol 6.457 5 1,000 Quadratic 1/x 7.5 Pentachlorobenzene 6.566 0.1 1,000 Linear 1/x2 4.8 Tecnazene 7.118 0.1 1,000 Linear 1/x2 3.9 Diphenylamine 7.186 0.1 1,000 Quadratic 1/x2 6.5 Ethoprophos 7.238 5 1,000 Quadratic 1/x 12.3 2,3,5,6-Tetrachloroaniline 7.297 0.5 1,000 Linear 1/x2 4.9 Chlorpropham 7.325 0.5 1,000 Quadratic 1/x 7.5 Trifluralin 7.462 1 1,000 Quadratic 1/x2 6.6 Benfluralin 7.496 0.1 1,000 Quadratic 1/x2 7.2 BHC-alpha (Benzene Hexachloride) 7.881 1 1,000 Linear 1/x2 1.0 2,6-Diisopropylnaphthalene 8.02 5 1,000 Quadratic 1/x 5.5 Hexachlorobenzene 8.024 0.5 1,000 Quadratic 1/x 4.5 Ethoxyquin 8.034 0.1 1,000 Quadratic 1/x2 25.3 Dichloran 8.04 1 250 Linear 1/x2 7.7 Simazine 8.043 5 1,000 Linear 1/x2 7.0 Pentachloroanisole 8.073 0.1 1,000 Linear 1/x2 3.3 Atrazine 8.124 1 1,000 Linear 1/x2 5.5 Beta-BHC 8.278 1 1,000 Linear 1/x2 4.9 Terbuthylazine 8.363 1 1,000 Linear 1/x2 14.6 BHC-gamma (Lindane, Gamma HCH) 8.398 1 1,000 Linear 1/x2 4.5 Pentachloronitrobenzene 8.478 0.5 1,000 Quadratic 1/x2 33.7 Pentachlorobenzonitrile 8.515 0.1 1,000 Quadratic 1/x2 3.1 Diazinon 8.526 0.5 1,000 Linear 1/x2 5.8 Pyrimethanil 8.53 0.1 1,000 Linear 1/x2 5.0 BHC-delta 8.763 1 1,000 Quadratic 1/x 11.4 Triallate 8.817 1 1,000 Quadratic 1/x2 4.4 Iprobenfos 8.942 0.5 1,000 Quadratic 1/x2 17.3 Pirimicarb 8.976 1 1,000 Linear 1/x2 8.9 Pentachloroaniline 9.178 0.1 1,000 Linear 1/x2 4.6 Propanil 9.193 0.5 1,000 Quadratic 1/x2 11.4 Metribuzin 9.256 0.5 1,000 Quadratic 1/x2 5.8 Dimethachlor 9.255 0.5 1,000 Linear 1/x2 6.0 Vinclozolin 9.372 0.1 1,000 Linear 1/x2 9.5 Chlorpyrifos-methyl 9.404 0.1 1,000 Quadratic 1/x2 8.4 Parathion-methyl 9.403 5 1,000 Quadratic 1/x 9.3 Ametryn 9.495 0.5 1,000 Quadratic 1/x2 6.5 Tolclofos-methyl 9.496 5 1,000 Linear 1/x2 5.8 Prometryn 9.541 0.1 1,000 Quadratic 1/x2 6.9 Pirimiphos-methyl 9.85 0.5 1,000 Quadratic 1/x2 8.9 Fenitrothion 9.855 0.1 1,000 Quadratic 1/x2 10.2 13 Name Retention Time (minutes) Min Cal (ppb) Max Cal (ppb) Curve Fit Curve Weight %RSD Ethofumesate 9.877 0.5 1,000 Quadratic 1/x2 6.5 Malathion 9.995 10 1,000 Quadratic 1/x 20.0 Pentachlorothioanisole 10.032 0.1 1,000 Linear 1/x2 3.5 Metolachlor 10.166 5 1,000 Linear 1/x2 6.2 Fenthion 10.187 0.5 1,000 Linear 1/x2 2.4 Chlorpyrifos 10.224 0.5 1,000 Linear 1/x2 4.5 Parathion 10.242 1 1,000 Linear 1/x2 2.7 Triadimefon 10.275 0.5 1,000 Quadratic 1/x 11.6 Tetraconazole 10.319 0.5 1,000 Quadratic 1/x2 7.5 DCPA (Dacthal, Chlorthal-dimethyl) 10.328 0.1 1,000 Quadratic 1/x 7.3 Isocarbophos 10.346 0.1 1,000 Linear 1/x2 4.7 Butralin 10.496 0.5 1,000 Linear 1/x2 5.7 Cyprodinil 10.672 0.5 1,000 Linear 1/x2 7.8 MGK-264 10.709 0.1 1,000 Linear 1/x2 7.3 Pendimethalin 10.797 0.5 1,000 Linear 1/x2 4.6 Penconazole 10.826 0.5 1,000 Quadratic 1/x2 9.8 Heptachlor Exo-epoxide 10.904 10 1,000 Quadratic 1/x 14.1 Fipronil 10.915 0.5 1,000 Quadratic 1/x 10.7 Triadimenol 11.008 0.5 1,000 Quadratic 1/x2 7.1 Quinalphos 11.01 1 1,000 Linear 1/x2 3.3 Chlordane-trans 11.326 100 1,000 Quadratic 1/x 13.6 DDE-o,p' 11.363 0.1 500 Quadratic 1/x2 11.8 Mepanipyrim 11.458 0.5 1,000 Linear 1/x2 7.1 Flutriafol 11.596 0.5 1,000 Quadratic 1/x 6.6 Flutolanil 11.664 0.5 1,000 Quadratic 1/x2 4.6 Napropamide 11.697 0.5 1,000 Linear 1/x2 8.5 Hexaconazole 11.73 0.5 1,000 Linear 1/x2 8.6 Isoprothiolane 11.776 0.1 1,000 Linear 1/x2 4.8 Prothiofos 11.782 0.5 1,000 Linear 1/x2 5.2 Fludioxonil 11.819 0.5 1,000 Quadratic 1/x2 6.9 DEF 11.871 0.5 1,000 Linear 1/x2 7.4 DDE-p,p' 11.91 0.1 500 Quadratic 1/x2 9.8 Oxyfluorfen 11.988 0.5 1,000 Linear 1/x2 5.2 Myclobutanil 12.013 0.5 1,000 Quadratic 1/x2 8.2 Buprofezin 12.066 1 1,000 Quadratic 1/x2 6.2 Bupirimate 12.089 0.5 1,000 Linear 1/x2 6.7 Kresoxim-methyl 12.093 0.5 1,000 Quadratic 1/x 5.9 Chlorfenapyr 12.326 0.5 1,000 Quadratic 1/x2 4.8 Endrin 12.425 5 1,000 Quadratic 1/x 10.3 Ethion 12.718 5 1,000 Linear 1/x2 7.5 Benalaxyl 13.167 0.5 1,000 Quadratic 1/x2 7.7 Trifloxystrobin 13.223 0.5 1,000 Linear 1/x2 5.3 Quinoxyfen 13.222 0.1 1,000 Linear 1/x2 7.7 Endosulfan Sulfate 13.328 1 1,000 Quadratic 1/x2 13.2 Tebuconazole 13.565 0.5 1,000 Quadratic 1/x2 6.6 Nuarimol 13.595 0.5 1,000 Quadratic 1/x2 6.4 Triphenyl Phosphate 13.659 0.5 1,000 Quadratic 1/x2 6.1 14 Name Retention Time (minutes) Min Cal (ppb) Max Cal (ppb) Curve Fit Curve Weight %RSD Piperonyl butoxide 13.662 0.5 1,000 Quadratic 1/x2 5.9 Epoxiconazole 13.876 0.5 1,000 Quadratic 1/x2 8.5 Spiromesifen 14.014 1 1,000 Quadratic 1/x 15.5 Tetramethrin I 14.207 0.5 1,000 Quadratic 1/x 7.4 Bifenthrin 14.179 0.5 1,000 Quadratic 1/x2 4.4 EPN 14.226 10 1,000 Quadratic 1/x2 5.8 Bromopropylate 14.221 0.5 1,000 Quadratic 1/x2 5.2 Etoxazole 14.375 0.5 1,000 Quadratic 1/x2 6.3 Tebufenpyrad 14.398 0.5 1,000 Quadratic 1/x2 6.9 Fenamidone 14.449 0.5 1,000 Quadratic 1/x2 7.4 Tetradifon 14.72 5 1,000 Quadratic 1/x2 9.2 Metrafenone 15.648 0.5 1,000 Quadratic 1/x2 6.4 Bitertanol I 15.857 0.5 1,000 Quadratic 1/x2 9.7 Spirodiclofen 15.976 5 1,000 Quadratic 1/x2 49.3 Pyridaben 16.081 0.5 1,000 Quadratic 1/x2 5.8 Cyfluthrin I 16.484 5 1,000 Quadratic 1/x2 22.2 Fenbuconazole 16.535 5 1,000 Quadratic 1/x2 9.5 Cypermethrin I 16.8 5 1,000 Quadratic 1/x 23.8 Boscalid 16.909 0.1 1,000 Quadratic 1/x2 8.4 Ethofenprox 17.096 0.5 1,000 Quadratic 1/x2 5.9 Difenoconazole I 18.148 1 1,000 Quadratic 1/x 12.4 Azoxystrobin 18.787 10 1,000 Quadratic 1/x2 11.2 Dimethomorph I 19.175 5 1,000 Quadratic 1/x 15.3 www.agilent.com DE34182072 This information is subject to change without notice. © Agilent Technologies, Inc. 2024 Printed in the USA, May 3, 2024 5994-7385EN Conclusion The analytical performance of the Agilent 7010 Series triple quadrupole mass spectrometer (GC/TQ) upgraded with the HES 2.0 electron ionization (EI) source was demonstrated for multiresidue pesticide analysis. The system demonstrates analytical sensitivity as the same or better than the original HES as well as excellent accuracy and robustness. The 7010 GC/TQ with HES 2.0, coupled with an Agilent 8890 GC with an MMI inlet and 15 m × 15 m mid-column backflush configuration minimizes instrument downtime by allowing for inlet maintenance without requiring the cooling of the heated zones. With no impact to the analytical method or degradation of the instrument performance, this application demonstrates the ability of the instrument to provide robust and reliable analytical results, including for challenging matrices. References 1. Anastassiades, M.; Lehotay, S. J.; Stajnbaher, D.; Schenck, F. J. Fast and Easy Multiresidue Method Employing MeCN Extraction/Partitioning and “Dispersive Solid-Phase Extraction” for the Determination of Pesticide Residues in Produce. J. AOAC Int. 2003, 86, 412− 431. 2. Pesticide Residues in Foods by MeCN Extraction and Partitioning with Magnesium Sulfate. Official Methods of Analysis of AOAC International; AOAC International: Gaithersburg, MD, 2007; Method 2007.1. 3. Lehotay, S. J. QuEChERS Sample Preparation Approach for Mass Spectrometric Analysis of Pesticide Residues in Foods. Methods Mol. Biol. 2011, 747, 65–91. doi: 10.1007/978-1-61779-136-9_4. PMID: 21643905. 4. Alder, L.; Greulich, K.; Kempe, G.; Vieth, B. Residue Analysis of 500 High Priority Pesticides: Better by GC-MS or LC–MS/ MS? Mass Spectrom. Rev. 2006, 25, 838–865. 5. Chamkasem, N.; Ollis, L. W.; Harmon, T.; Lee, S.; Mercer, G. Analysis of 136 Pesticides in Avocado Using a Modified QuEChERS Method with LC-MS/MS and GC-MS/MS. J. Agric. Food Chem. 2013, 61(10), 2315–2329. DOI: 10.1021/jf304191c 6. Lehotay, S. J.; Han, L.; Sapozhnikova, Y. Automated Mini-Column Solid-Phase Extraction Cleanup for High-Throughput Analysis of Chemical Contaminants in Foods by Low-Pressure Gas Chromatography-Tandem Mass Spectrometry. Chromatographia 2016, 79(17), 1113–1130. DOI: 10.1007/s10337-016-3116-y. 7. Andrianova, A.; Zhao, L. Five Keys to Unlock Maximum Performance in the Analysis of Over 200 Pesticides in Challenging Food Matrices by GC/MS/MS. Agilent Technologies application note, publication number 5994-4965EN, 2022.