Development and validation of a screening method for drug residues in fish, shrimp and eel using LC-HRMS Sherri Turnipseed 1, Joseph Storey 1, Robert Burger 2, Aaron Johnson 2, Jack Lohne 1, Wendy Andersen 1, Mark Madson 1, 2 1 Animal Drugs Research Center, US FDA, Denver, CO 2 Denver Laboratory, US FDA, Denver, CO
Objectives Develop analytical screening method for veterinary drug residues in fish using HRMS. Optimize and validate method for 60 test compounds most likely to be used in aquaculture. Use HRMS capability with vet drug database to screen samples for ~270 additional compounds.
Test Compounds Class Drugs Target testing level (ng/g) Tetracyclines Tetracycline, Oxytetracycline, Doxycycline, Chlortetracycline 100 Fluoroquinolones Ciprofloxacin, Enrofloxacin, Norfloxacin, Sarafloxacin, Difloxacin, 5 Danofloxacin Quinolones Oxolinic Acid, Flumequine, Naladixic Acid 10 Sulfonamides Sulfaclozine, Sulfamonomethoxine, Sulfachloropyridazine, 10 Sulfadimethoxine, Sulfadiazine, Sulfadoxine, Sulfaethoxypyridazine, Sulfamethoxypyridazine, Sulfamerazine, Sulfamethoxazole, Sulfamethazine, Sulfapyridine, Sulfaquinoxaline, Sulfathiazole Potentiators Trimethoprim, Ormetoprim 10 Macrolides Erythromycin, Tylosin, Azithromycin, Tilmicosin, Spiramycin 50 Lincomycins Lincomycin 50 β-lactams Amoxicillin, Ampicillin, Penicillin G, Cloxacillin, Dicloxacillin, Oxacillin, 25 Aspoxicillin, Cephapirin (amox 100) Benzimidazoles Albendazole, Albendazole Sulfoxide, Fenbendazole, 50 Fenbendazole Sulfone Avermectins Emamectin, Ivermectin, Doramectin 200 Nitromidazoles Metronidazole, Ketoconazole 10 Dyes Malachite Green, LeucoMG, Crystal Violet, LeucoCV, Brilliant Green 1 Steroids Methyl-testosterone 0.8 Phenicols Florfenicol Amine 50 Preservative Ethoxyquin 50
Acidic acetonitrile (ACN) extraction Extraction Procedure 2 g tissue Add 8 ml ACN with 0.2% p-toluene sulfonic acid and 2% glacial acetic acid Centrifuge OASIS HLB PRiME SPE (200 mg) Pass 3 ml of extract through SPE Evaporate to near dryness Reconstitute in 400 μl 10% ACN in water Centrifuge Aliquot portion to LC vial See Poster #P27 for more information
Data Acquisition LC: MS: Thermo Ultimate 3000 LC system with Supelco Ascentis Express C18 fused-core reversed-phase column. Mobile phase 0.1 % formic acid and acetonitrile (ACN) at 0.3 ml/min. 0.0-1.5 min 5% ACN 1.5-8.5 min to 50% ACN 8.5-9.0 min to 99% ACN 9.0-12 min 99% ACN Thermo Q-Exactive Orbitrap high resolution MS with a heated electrospray source Two different acquisition programs were evaluated: All Ion Fragmentation Data Dependent MS 2
Data Acquisition All Ion Fragmentation (AIF) After MS 1 scan, collect data for ALL precursor ions Nontargeted approach Collect product ion data for all precursor ions at once Can vary and combine different collision energy values Can filter limited range of precursor ions ( DIA ) Nontargeted- get information for all ions in sample Can be more difficult to establish relationships between precursor and product ions, don t get clean spectra
Data Acquisition Data dependent MS 2 (DDMS 2 ) After MS 1 scan, collect data for specified precursor ions Targeted approach if use inclusion list Usually collect product ion data only if precursor ion abundance is above threshold (data dependent) Can specify time window, collision energy Cleaner spectra, better precursor- product ID, can be more selective Only acquire product ion spectra for compounds already on a list (targeted), requires instrument time to perform (duty cycle), may miss compounds
AIF MS 1 data for spiked sample Amoxicillin Sulfathiazole Sarafloxacin Tilmicosin Oxolinic acid Quan Peak: 366.11182 m/z Peak Area: 235655 RT: 1.80 min (1.80) Amount: 95 ng/g Quan Peak: 256.02089 m/z Peak Area: 4698824 RT: 3.63 min (3.60) Amount: 9.5 ng/g Quan Peak: 386.13107 m/z Peak Area: 9974652 RT: 5.15 min (5.40) Amount: 4.6 ng/g Quan Peak: 435.29030 m/z Peak Area: 83163280 RT: 6.00 min (6.09) Amount: 44 ng/g Quan Peak: 262.07100 m/z Peak Area: 23549248 RT: 6.49 min (6.60) Amount: 9.5 ng/g Tilapia spiked with 60 compounds at target testing level. Oxytetracycline Quan Peak: 461.15546 m/z Peak Area: 19533822 RT: 4.46 min (4.70) Amount: 93 ng/g Leucomalachite green Quan Peak: 331.21688 m/z Peak Area: 433792 RT: 8.20 min (8.24) Amount: 0.78 ng/g Methyl testosterone Quan Peak: 303.23186 m/z Peak Area: 1883594 RT: 9.38 min (9.40) Amount: 0.37 ng/g Ivermectin B1a Quan Peak: 897.49708 m/z Peak Area: 9208651 RT: 11.87 min (12.00) Amount: 130 ng/g MS 1 data shown. Also collected MS 2 data and evaluated RT and isotopic match.
AIF data for spiked sample Emamectin in salmon at 1X (200 ng/g) MS 1 quan peak Fragment Ions Isotope match Experimental Experimental Theoretical Theoretical Match between experimental and theoretical easy to see
AIF data for spiked sample Ciprofloxacin in catfish at 1X (5 ng/g) MS 1 quan peak Fragment Ions Experimental Isotope match Experimental Theoretical Theoretical Match between experimental and theoretical not obvious- obscured by other ions
AIF data for spiked sample Ciprofloxacin in catfish at 1X (5 ng/g) PRODUCT IONS Experimental = m/z 245.10872 Δ = 0.893 ppm Experimental = m/z 288.15082 Δ = 0.409 ppm Theoretical = m/z 245.10850 Theoretical = m/z 288.15070 ISOTOPE IONS Software is able to analyze data using very narrow mass windows to determine if there is a match
100 AIF MS 2 data for spiked sample NL: 5.90E6 275.14973 Spiked Tilapia 1X- AIF Oxytetracycline (100 ng/g) Product Ion Spectrum Known ions for oxytetracycline Relative Abundance 50 141.00037 *154.04973 259.11874 246.99450 158.02693 334.21213 216.99039 * 164.10690 426.11783 176.10685 201.05441 232.96433 285.98264 346.21214 443.14463 410.99160 320.14014 461.15513 200 300 400 480 m/z
200 300 400 480 m/z 100 DDMS 2 data for spiked sample NL: 1.59E5 426.11853 Spiked Tilapia 1X- DDMS 2 Oxytetracycline (100 ng/g) Product Ion Spectrum Known ions for oxytetracycline Relative Abundance 50 201.05478 461.15643 443.14499 154.04984 283.06024 381.06061 337.07031 226.07172 365.06570 268.03708 350.04279 239.07092 307.06003 322.04709 408.10858
FDA Criteria for ID using HRMS data MS mode Single MS MS/MS MS 1 and MS/MS S/N greater than or equal to 3, or equal or above preset relative intensity to the comparison standard EIC: signal requirement (absolute) EIC: retention time MS: Number of structurally significant ions MS: mass accuracy* 0.2 min, or within 2.5% or less (not to exceed 0.5 min), or within an established error range, (not to exceed 0.5 min) minimum 2 minimum 2 minimum 2 combined 5 ppm 10 ppm MS 1 5 ppm; MS/MS 10 ppm From guidance Acceptance Criteria for Confirmation of Identity of Chemical Residues using Exact Mass Data for the FDA FVM Program See Poster #P31 for more information
Fortified samples: 60 validation compounds Validation of Method 5 species (salmon, tilapia, catfish, shrimp, eel) 2-3 sources for each species of fish Fortified at target testing level (1X) to determine threshold for limits test Also fortified at 2X, 0.5X, and 0.1X to determine minimum detection levels and lowest confirmation levels by AIF and DDMS 2 Determined false positive and false negative rates; approximate recoveries compared to solvent standards Based on FDA OFVM Guidelines for Validation of Chemical Methods v2
Comparison of AIF and DDMS 2 Residues confirmed at 1X target testing level Confirmed = MH + (5 ppm), one fragment (10 ppm), RT match and isotope pattern match (optional) AIF > 90% validation compounds confirmed at 1X Most confirmed at much lower levels (0.1-0.5X of target testing level) DDMS 2 ~ 70% of validation compounds depending on matrix Compounds with low target testing levels (dyes) or low method recovery(β-lactams) don t meet threshold to trigger data dependent MS 2 Some confirmed at higher levels
Presumptive Positive Meet Criteria for Confirmation of Identity Using Exact Mass Data Signal:noise ratio: 3 Retention time match: 0.5 min Mass accuracy: 5 ppm for MH + 10 ppm for at least one fragment ion (AIF or DDMS 2 ) Signal Intensity (EIC of MH + ) 50% compared to matrix-extracted standard at TTL
Screening False Negative Rates 60 50 40 30 # analytes AIF # analytes DDMS2 20 10 0 < 5% 5-10% >10% False Negative Rate False negative rate = # times analyte not presumptive positive/total samples fortified at 1X 60 analytes tested, 77 samples fortified at 1X
Screening False Positive Rates # Analytes False Positive in blank tissue False Positive > 0% 1 (sulfacetamide) AIF DDMS 2 0 False positive rate = # times analyte presumptive positive/total blank samples 60 analytes tested, 48 blank tissue samples * Results for sulfacetamide were not suitable for method to be used as screen for this residue
Work Flow (1) 1) Initial Data Acquisition by Q-Exactive: All Ion Fragmentation a) Targeted Data Analysis: Limit testing and identification of test compounds Use TraceFinder Quant to analyze for 60 test compounds Match 5 ppm window (MS 1 ), 0.5 min retention time, one fragment ion (10 ppm) Compare to matrix-extracted standard fortified with test compounds at TTL Determine if analytes are identified and > threshold cutoff level (>50% TTL signal) b) Semi-targeted Data Analysis: Expand screening for more drug residues Use TraceFinder Screening to search against larger analyte database (N > 330) Use 3 ppm window with higher signal criteria to limit false positives Compare RT and fragment ions if known Determine if other analytes are present and can be identified
Work Flow (2) 2) Additional Data Acquisition by Q-Exactive: Data Dependent MS 2 Data Analysis of Product Ion Spectra Examine product ion spectra obtained for analytes on inclusion list Focus on residues found in initial analysis Use TraceFinder Quant and Screening to compare residues to database Follow up with manual evaluation of spectral data Compare to library spectra if available
Application of Method Representative incurred and violative regulatory samples: Catfish dosed with enrofloxacin Tilapia dosed with sulfadiazine or sulfadiazine + trimethoprim Regulatory samples found violative to confirm original findings and look for additional residues
Presumptive positive for SDZ Data from Incurred Fish - AIF Other test compounds found (< 50% TTL): Sulfadiazine Ethoxyquin methyl testosterone Crystal violet (Gentian Violet) Quan Peak: 251.05972 m/z Peak Area: 154132987 RT: 2.63 min (2.60) Amount: 254 ng/g (25X) Quan Peak: 218.15394 m/z Peak Area: 163773 RT: 7.64 min (7.70) Amount: 0.1 ng/g < 0.1X Quan Peak: 303.23186 m/z Peak Area: 230974 RT: 9.58 min (9.40) Amount: 0.05 ng/g <0.1X Quan Peak: 372.24342 m/z Peak Area: 457071 RT: 8.87 min (9.00) Amount: 0.1 ng/g ~ 0.1X From screening larger database compounds (N > 330): N4Acetyl Sulfadiazene AA: 9931362 RT: 4.19 (4.25) Ethoxyquin Dimer AA: 1802672 RT: 11.73 (N/A) Tilapia dosed with sulfadiazene m/z: 293.0705 (293.0703) Fragments:108.04*,198.02*, 136.06 D m/z (ppm): 0.6 m/z: 433.2855 (433.285) Fragments: N/A D m/z (ppm): 1.25
Data from Incurred Fish - DDMS 2 100 156.01165 Product ions of SDZ Relative Abundance 50 108.04449 92.04956 96.05575 251.05982 68.04973 185.08244 150 200 250 m/z 100 Product ions of N 4 acetyl SDZ 293.07037 Relative Abundance 50 65.03887 93.03370 108.04456 96.05579 120.08117 134.06023 198.02226 227.09305 150.05528 176.01317 246.99519 270.97479 50 100 150 200 250 300 m/z
Data from Regulatory Eel - AIF Presumptive positive for test compounds Sulfamethazine Quan Peak: 279.09102 m/z RT: 4.66 min Amount: 85 ng/g Enrofloxacin Quan Peak: 360.17180 m/z RT: 4.89 min Amount: 58 ng/g Ciprofloxacin Quan Peak: 332.14050 m/z RT: 4.63 min Amount: 44 ng/g Trimethoprim Quan Peak: 291.14517 m/z RT: 4.16 min Amount: 22 ng/g Ethoxyquin Quan Peak: 218.15394 m/z RT: 7.58 min Amount: 87 ng/g Other test compounds found (< 50% TTL) Lincomycin Quan Peak: RT: Amount: 407.22103 m/z 3.66 min 11 ng/g Oxytetracycline Quan Peak: 461.15546 m/z RT: 4.50 min Amount: 1.8 ng/g
Data from Eel - AIF From screening larger database compounds (N > 330): Ethoxyquin Dimer AA: 3341515 RT: 11.72 min m/z: 433.285 (433.285) D m/z (ppm): 0.05 N4-acetyl-sulfamethazine AA: 4372013 RT: 5 min m/z: 321.1013 (321.1016) D m/z (ppm): -0.85 Desethylene Enrofloxacin AA: 1424542 RT: 4.57 min m/z: 334.157 (334.1562) D m/z (ppm): 2.4
100 126.12776 C 8 H 16 N + Data from Eel DDMS 2 Relative Abundance 50 Product Ions of Lincomycin C 17 H 31 O 6 N 2 + 359.21686 407.22086 MH + C 18 H 35 O 6 N 2 S + 100 100 NL: 200 300 400 m/z Product Ions of Ethoxyquin dimer 433.28546 MH + C 28 H 37 O 2 N + 2 Relative Abundance 50 216.13934 C 14 H 18 ON + 188.10765 231.14949 417.25397 C C 14 H 19 ON + 12 H 14 ON + 2 375.20670 C 24 H 27 O 2 N + 2 333.16031 100 200 300 400 m/z
Conclusions HRMS screening method was able to identify 60 test compounds at or below their target testing level. All Ion Fragmentation was the most useful data acquisition for screening. Data Dependent MS 2 acquisition provided product ion spectra for most residues at TTL. The method confirmed results found by LC-MS/MS. Detection and identification of other residues including metabolites demonstrated ability to expand screening in aquacultured products.