Pesticide Analysis Workflow Using Hyphenated Mass Spectrometry Techniques Chinkai (Kai) Meng, Ph.D. Senior Applications Chemist Wilmington, Delaware USA chin_meng@agilent.com com February 12, 2009 Page 1
MS Techniques Outline MS Analyzers Selection GC/MS deconvolution and backflush QQQ (MS/MS) LC/Q-TOF Summary Page 2
Analytical Instrumentations Chromatography (Separation the best friend of any detector) GC volatile and semi-volatile non-polar compounds LC polar or moderately polar or thermally labile compounds Detectors GC (element selective, FPD, NPD, ECD) high sensitivity, poor specificity LC (UV, FLD) general purpose, limited sensitivity MS SQ: high confidence from spectral confirmation, limited MDL QQQ: low detection limits of target compounds in dirty matrices (MRM) TOF/Q-TOF: always full spectrum and accurate mass for screening TOF-TOF, Q-Trap, and others (generally not for ROUTINE use). Page 3
Guiding Principles in MS Analyzer Selection The correct choice of analyzer depends on whether one is LOOKING for UNKNOWNS or whether one is CONFIRMING & MEASURING KNOWNS. The correct choice of analyzer depends on the COMPLEXITY of the MATRIX. Page 4
Basic Questions Which MS Solution Target analysis only? Scan or SIM or MS/MS Analysis of unknowns? Scan MS with Quad, IT or TOF How much chemical noise from the matrix? How much sample prep? Deconvolution or MS/MS Backflush or MS/MS Page 5
General Workflow: Screen S, Confirm C and Quantify Q Representative Sample GC/MS (PTV) SIM/Scan for known and unknown Deconvolution Final Report S C (+backflush) Q QuEChERS GC/QQQ MRM for known targets LC/QQQ MRM for known targets S Extraction 1 3 S C C Q Q 1 3 LC/QTOF or TOF Full Spectrum for unknown compounds Exact Mass Database Search Clean-up 1 3 S Molecular Formula Generation Q Another injection for MS/MS (QQQ or QTOF) C C16 H19 N3 P Cl C15 H25 O P S Cl C18 H21 O P Cl Page 6
MS Techniques Outline MS Analyzers Selection GC/MS deconvolution and backflush QQQ (MS/MS) LC/Q-TOF Summary Page 7
TICs of Surface Water Extracts How many pesticides (drugs, allergens etc.) are in these samples and how long does it take you to confirm? 5.00 10.00 15.00 20.00 25.00 30.00 35.00 40.00 5.00 10.00 15.00 20.00 25.00 30.00 35.00 40.00 5.00 10.00 15.00 20.00 25.00 30.00 35.00 40.00 Page 8
17 Surface Water TICs (Scan): Pesticide Analysis Using DRS with Pesticide Database (927 entries) Targets Found (not counting ISTD) CDFA* 37 Agilent DRS Same 37 +99 more False Positives 1 0 Processing Time ~8 hrs 32 min DRS: Deconvolution Reporting Software Saving 7.5 hours *CDFA is the California i Department t of Food and Agriculture Page 9
How Does Deconvolution Work? 50 17 0 28 0 18 5 75 16 31 0 0 Page 10
Eliminate Ions Don t Fit the Criteria 50 17 0 28 0 18 5 75 16 31 0 0 Ion grouping criteria: 1. Same RetTime at apex 2. Same peak width Page 11 16 500 17 028 180 5 75 31 0 Extracted Ion Chromatograms (EIC)
Spectrum is Deconvoluted/Cleaned 17 0 50 28 0 A component in AMDIS 50 17 028 0 Related ions are grouped together as a component. Page 12
TIC of Spinach Extract More than 370 peaks found 5.00 10.00 15.00 20.00 25.00 30.00 35.00 40.00 Deconvolution Library Search
QEdit, p,p -DDT selected 5ion overlay MSD ion AMDIS ion MSD & AMDIS areas & amounts x and A 3 spectra indicators Page 14
Pesticides in Red Wine - Fenpropathrin Found by AMDIS 250 ppb 100 250 ppb Not found Raw scan 1 ppm MF = 65 83 MF = 783 Deconvoluted Fenpropathrin 5 ppm Library entry MF = 877 Fenpropathrin Page 15
Without Backflush: Increased Chemical Background (Spectral Noise) and Changes in Retention Time 4.6e+07 4.2e+07 Increased baseline and spectral noise due to carryover of matrix 3.8e+07 3.4e+07 3e+07 2.6e+07 2.2e+07 1.8e+07 Highly retained matrix is altering the column selectivity and changing the retention time B A 1.4e+07 1e+07 6000000 2000000 0 4.00 6.00 8.00 10.00 12.00 14.00 16.00 18.00 20.00 Overlay of two chromatograms of a blank extract injected BEFORE (A) and AFTER (B) three injections without backflush Page 16
With Backflush: No Increased Chemical Background (Spectral Noise) and No Change in Retention Time 4.6e+07 4.2e+07 3.8e+07 Stable retention times and baseline... less chemical noise - less maintenance - better results 3.4e+07 3e+07 2.6e+07 2.2e+07 1.8e+07 1.4e+07 1e+07 6000000 2000000 0 4.00 6.00 8.00 10.00 12.00 14.00 16.00 18.00 20.00 Overlay of three chromatograms of lettuce extract run with 2 min of backflush Page 17
MS Techniques Outline MS Analyzers Selection GC/MS deconvolution and backflush QQQ (MS/MS) LC/Q-TOF Summary Page 18
Analyzers for Trace Target Compounds Who should use QQQ (MS/MS)? User doing Selected Ion Monitoring (SIM) for target compound analysis in traditional markets, needing additional sensitivity and selectivity with less sample prep, to meet more demanding analytical requirements. GC/QQQ MRM for known targets S LC/QQQ MRM for known targets S C C Q Q Page 19
Multiple Reaction Monitoring (MRM) Quad Mass Filter (Q1) Collision Cell Quad Mass Filter (Q3) Spectrum with background ions (from EI) 210 222 Q1 lets only target ion 210 pass through 210 Collision cell Q3 monitors only breaks ion 210 characteristic apart fragments 158 and 191 from ion 210 for quant and qual. 268 158 280 158 165 191 210 191 170 210 250 290 190 210 150 170 190 210 160 190 no chemical background Page 20
Why MS/MS? Greater Selectivity Than SIM EI-SIM selectivity proportional to spectral resolution no selectivity against ions with same m/z interference analyte EI-MS/MS Precursor selectivity same as SIM High probability that at least one product ion will be a unique dissociation product of the precursor BUT not the interference Product 2 unit mass resolution Product 3 Product 1 interference Precursor Ion The precursor ion should NOT be used for ion ratios or quantitation since the interferences will be the same as the SIM ion Page 21
SIM vs MRM for HCB 100 fg HCB in Clean Matrix Single MS: SIM 283.8 S/N=26:1 RMS Injecting 100 fg of Hexaclorobenzene (HCB) and analyzing in SIM. MS/MS: 28 83.8:213.9 Injecting 100 fg of Hexaclorobenzene (HCB) and analyzing in MRM. RMS S/N=37:1 You obtain the same S/N! Page 22
SIM vs MRM for HCB 100 fg HCB in Clean Matrix 300 fg HCB in Diesel Single MS: SIM 283.8 S/N=26:1 RMS S/N=6:1 RMS MS/MS: 28 83.8:213.9 S/N=37:1 RMS S/N=86:1 RMS Page 23
Comparing GC/Q SIM to GC/QQQ MRM in Various Matrices Analysis of p,p -DDE at 10 ppb (All injections = 1 µl) SIM - EIC (246) MRM (246->176,175) Apple S/N = 448 Cabbage S/N = 241 Ginseng S/N = 446 Orange S/N = 456 Spinach S/N = 260 Page 24
Carrot Extract - 1 µl with GC/QQQ is Much Better than 5 µl GC/Q GC/Q GC/QQQ 5 µl (Multi-mode Inlet) 1 µl Pesticide Cold SL Scan + DRS Cold SL SIM Hot SL (ppb) Diclobenil 0.38* Pentachlorobenzene 075* 0.75 Trifluralin 2.3* Tefluthrin 0.53* 4,4'-Dichlorobenzophenone 1.2* Chlorpyrifos 24.7 o,p'-dde 3.7 p,p'-dde X X 240 o,p'-ddd 9 pp'ddd p,p'-ddd X o,p'-ddt X Sum = 45 p,p'-ddt X X 130 Fenazaquin X Not in Method * = Below Calibration Level Page 25
p,p -DDE in Carrot Extract (240 ppb) 5 µl GC/Q vs. 1 µl GC/QQQ 5 µl Cold SL Scan EIC S/N = 35 5 µl Cold SL SIM EIC S/N = 375 1 µl Hot SL QQQ MRM 246.0 -> 176.1, 246.0 -> 175.1 x10 5 13 1.3 1.2 1.1 1 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0-0.1 Ratio=23.8 S/N = 434 11.8 11.9 12 12.1 12.2 12.3 Acquisition Time (min) Page 26
Why a GC/MS/MS System? Allows for the selective quantitation of target compounds in high chemical background samples Better S/N in complex matrices than can be achieved by single quadrupole scan or SIM approaches. Newer regulations in some markets specify analytical power commensurate with GC/MS/MS Page 27
Technology Agilent took the best technologies from their industry leading 597X Series GC/MSD: Heated monolithic gold plated quartz quadrupole Proven reliable high performance source design AUTOTUNE and the 6410A LC/QQQ: Linear acceleration enhanced Collision Cell Wide Mass-Bandwidth QQQ ion optics MassHunter software Page 28
Why Heated Quartz Gold Quads? Unlike LC/MS, many high boiling neutral molecules enter the source and manifold of a GC/MS or GC/MS/MS Higher temperature reduces potential for contamination 200C max Virtually eliminates the need to clean quads Low coefficient for thermal expansion for quartz Stable structure during maintenance cycles (hot-cool-hot) for source or detector More stable tunes and methods over a longer period of time in real world sample environments Page 29
MS Technique Outline MS Analyzers Selection GC/MS deconvolution and backflush QQQ (MS/MS) LC/Q-TOF Summary Page 30
Agilent Q-TOF Fundamentals Two key concepts for TOF: 1. Exact Mass 2. Mass Error Collision cell Common with QQQ Ion optics Common with Q & QQQ Flight tube Common with TOF Ion Mirror Octopole 1 Quad Mass Filter (Q1) Octopole 2 Detector Lens 1 and 2 Collision Cell DC Quad Ion Pulser Rough Pump Turbo Turbo Turbo Turbo Page 31 September, 2008
Mass Analysis for TOF v = d/t E = ½ m v 2 = ½ m (d/t) 2 m = (2E/d 2 ) t 2 Energy (E) and Distance (d) are fixed The measured mass is proportional to the flight time (time-of-flight). Page 32
What does Exact Mass mean? 0.2874 amu Element Atomic Number Exact Mass H 1 1.007825 C 6 12.000000 N 7 14.003074 O 8 15.994915 C6H6Cl6 287.8600665 Lindane C10H12N2O6S 288.0416000 Carbasulam C9H21O2PS3 288.0441285 Terbufos C13H21O3PS 288.0949000 Iprobenfos C15H17N4Cl 288.1141743 Myclobutanil C12H21N2O4P 288.1238937 Diazoxon C11H20N4O3PS 288.1256000 Epronaz C11H21N4O3P 288.1351000 Pirimetaphos C16H20N2O3 288.1473925 Imazamethabenz The Key for getting useful TOF results is good mass accuracy. Uses accurate mass on TOF/Q-TOF to identify all of them. Page 33 September, 2008
Calculation of Error in Measured Mass (MH + ) of Reserpine Atom Mass of Atom # of Atoms Sum Hydrogen 1.00783 40 40.31300 Carbon 12.00000 33 396.00000 Nitrogen 14.00307 2 28.00615 Oxygen 15.99492 9 143.95424 Total 608.27338 Plus H 1.00783 1 1.00783 Total 609.28121 Minus e- 0.00055 1 0.00055 609.28066 Calculated = exact CH 3 O CH 3 (Measured - Calculated) X1000000 1,000,000 = ppm Calculated 0.9027038 ppm Error if the electron was not omitted! O CH 3 N H H O H O N O CH 3 O H CH 3 Reserpine (C 33 H 40 N 2 O 9 ) O O O CH 3 Page 34 September, 2008
TOF/Q-TOF Unlimited Number of Compound Screening 5556.D (Grape) MS1 Full Spectrum Molecular Feature Extractor found 510 compounds in the TIC. 15 out of 510 compounds had hits from EXACT MASS database search, i.e., these 15 matched entries in the database within 3 ppm mass accuracy. The three highlighted compounds were further confirmed by MS/MS. Page 35 September, 2008
Terbuconazole x10 4 7 6 5 4 3 2 The compound name Terbuconazole came up in the MS1 mode search. Use formula results and MS/MS results to confirm the hit. Cpd 11:+ Scan (13.974-14.248 min, 5 scans) 5556.d 121.05086 MS1 Full Spectrum 308.15216 C16H23ClN3O Cl 151.61282 N 125.57554 N H 3 C CH 3 N CH 3 OH 1 0 x10 4 6 5 4 3 2 1 0 Cpd 11:+ Product Ion (14.121 min) (308.15240[z=1] -> **) 5556.d 70.04052 C4H6O MS/MS Full Spectrum 125.01448 C7H6Cl 308.15199 60 80 100 120 140 160 180 200 220 240 260 280 300 320 340 Counts vs. Mass-to-Charge (m/z) Boxes represent theoretical isotope ratios Page 36
Screen Pesticides with LC-TOF/Q-TOF Accurate Mass provides added compound selectivity Higher resolution provides added interference selectivity Always full spectral data Unlimited number of compounds can be screened (search exact mass compound database for identification) Sensitivity is the same regardless of number of compounds screened* MS/MS (Q-TOF) assists compound confirmation *Triple quadrupole (QQQ) mass spectrometer can be more sensitive up to a limited number of compounds. That limit has not been definitively determined. Page 37
MS Technique Outline MS Analyzers Selection GC/MS deconvolution and backflush QQQ (MS/MS) LC/Q-TOF Summary Page 38
Summary GC/MS and Deconvolution to Screen, Confirm and Quantify QQQ for routine Targeted trace analysis in complex matrix MRM Sensitivity unsurpassed (up to a few hundred compounds) Complex matrix with less clean-up TOF/Q-TOF for Targeted and Unknown Screening Sensitive full scan analysis Searching exact mass database leads to identification Unlimited number of compounds Sensitivity is the same regardless of number of compounds screened Quantitative Accurate mass MS/MS for identification of fragments and structure elucidation (hotlink available to search on-line databases) Page 39
References Application Note 5989-7670: Replacing Multiple 50-Minute GC and GC- MS/SIM Analyses with One 15-Minute Full-Scan GC-MS Analysis for Non- targeted Pesticides Screening and >10x Productivity Gain Pesticide Brochure 5989-8652 GC-QQQ Brochure 5990-3152 Current Trends in Mass Spectrometry, pp 33-38, Nov. 2008 (Supplement to LC/GC North America): Comprehensive Screening, Confirmation, and Quantification of Organic Pesticides in Foods by GC-MS and LC-MS The Applications Book, LC/GC Europe, pp 9-11, Dec. 2008: The Benefits of Incorporating GC/QQQ into Pesticide id Analysis Methods Page 40
Thank you for your attention. Questions? January in Amsterdam Page 41