Welcome to our E-Seminar: Pesticide Analysis in a Complex Matrix using a 2D GC/MS System Slide 1
Multidimensional (2-D) GC Very old (>25 yrs) but powerful separation technique Based on cutting peak(s) from one GC column onto another with stationary phase of different selectivity Compounds that co-elute with analyte on first column separate from analyte on second column Example pairs of complimentary phases: HP-5MS (low polarity) with DB-17MS (polar) HP-5MS (low polarity) with Cyclosil (chiral) Slide 2
Simplified 2-Dimensional GC 7683 Autosampler Cut FID1 FID2 Column 1 Column 2 6890N GC Deans Switch Slide 3
Why 2-D GC? What s Changed? 6890 Simplified 2-D GC systems are much easier to use Column connections are easier, zero dead volume, inert, and reliable Balancing gas flows done with EPC and Flow Calculator Retention time drift greatly reduced with modern oven and EPC Inertness problems with switch hardware eliminated with surface coatings Because RT control is so tight and the switch is so quick, multiple ovens and cryo focusing devices can often be avoided Slide 4
Deans Hardware Restrictor Column 1 Column 2 Slide 5
Problems with OP Pesticides Organophosphorus (OP) pesticides are often present in citrus oils and need to be measured Citrus oil matrix is very complex and causes serious chromatographic interferences with identification and confirmation of OPs GC screening for OP compounds with phosphorus selective detector (FPD or AED) is useful, but offers limited identification and confirmation capability GC-MS would be desirable for identification and confirmation, but oil matrix interferences cause problems with spectral interferences Slide 6
Orange Oil GC-MS TIC (split 10:1) Orange Oil 5.00 10.00 15.00 20.00 25.00 30.00 35.00 Lemon Oil 5.00 10.00 15.00 20.00 25.00 30.00 35.00 Slide 7
System Configuration 7683 Autosampler FPD1 Deans Switch FPD2 Effluent Splitter Column 1 Column 2 6890N GC 5973N MSD Slide 8
OP Pesticides, Deans Setup, not Cutting Effluent from second column split between MSD and FPD in 10:1 ratio FPD2 FPD1 S/S Inlet restrictor 0.83 m x.1 mm UDFS HP-5MS 15m x.25 mm x 0.25 um MSD 3.9 ml/min 3.5 ml/min 2.2 ml/min 3.5 ml/min DB-17MS 30m x.25 mm x 0.25 um 1.3 ml/min (trickle purge) (<< 1mL/min) 4.8 ml/min solenoid valve 0.8 ml makeup added at splitter PCM 39.3 psig 33.6 psig 0.39 ml/min Slide 9
OP Pesticides, Deans Setup, Cutting Effluent from second column split between MSD and FPD in 10:1 ratio FPD2 FPD1 S/S Inlet restrictor 0.83 m x.1 mm UDFS HP-5MS 15m x.25 mm x 0.25 um MSD 3.9 ml/min 3.5 ml/min 2.2 ml/min 3.5 ml/min DB-17MS 30m x.25 mm x 0.25 um 1.3 ml/min 4.8 ml/min (trickle purge) (<< 1mL/min) solenoid valve 0.8 ml makeup added at splitter PCM 39.3 psig 33.6 psig 0.39 ml/min Slide 10
Break Number 1 Please type your question into the Chat Box at any time during the presentation. Slide 11
FPD1 Screen of Orange Oil A Signal: 17650NC.D\Fpd2b.ch Peak 1 50-100 ppb of OP compound Is it a pesticide? 5.00 10.00 15.00 20.00 25.00 30.00 35.00 Slide 12
FPD1 Screen of Orange Oil A Signal: 17650NC.D\Fpd2b.ch FPD1 (P mode) no cut Peak 1 Cut FPD1 (P mode) cut peak 1 24.00 24.50 25.00 25.50 26.00 26.50 27.00 27.50 Slide 13
Peak 1 Cut Results MS TIC of peak 1 cut Peak 1 FPD2 (P mode) of peak 1 cut 26.50 27.00 27.50 28.00 28.50 29.00 29.50 30.00 30.50 31.00 31.50 Slide 14
Spectrum and Search of Peak 1 Abundance 9000 8000 7000 6000 5000 4000 3000 m/z--> Abundance 97 Scan 2963 (31.122 min): 17650C2.D (-) 231 125 153 2000 65 384 1000 175 199 261283 315338 361 404 440 470495 0 0 50 100 150 200 250 300 350 400 450 500 Spectrum of peak 1 m/z--> 9000 8000 7000 6000 #127174: Ethion 231 5000 97 153 4000 125 3000 65 2000 384 29 1000 175 203 261 293 338 0 0 50 100 150 200 250 300 350 400 450 500 Library Match Spectrum: Ethion Match Quality 99% Slide 15
Spectrum If 2-D Not Used MS TIC of peak 1 cut Average Spectrum 26.50 27.00 27.50 28.00 28.50 29.00 29.50 30.00 30.50 31.00 31.50 Average Background Slide 16
Spectrum Unusable Without 2-D Abundance 9000 8000 7000 6000 5000 4000 3000 2000 1000 0 m/z--> Abundance 9000 8000 7000 6000 5000 4000 3000 2000 1000 0 m/z--> 47 41 67 93 Average of 29.399 to 31.203 min.: 17650C2.D (-) 135 231 Spectrum of peak 1 without 2-D separation 161 195 114 255 285305 384 338 362 406 451 471 497 50 100 150 200 250 300 350 400 450 500 69 93 119 161 189 #2848:.alpha.-Farnesene 50 100 150 200 250 300 350 400 450 500 Library Match: Ethion not listed in top 20 hits. Best match (30%) was alpha-farnesene Slide 17
FPD1 Screen of Lemon Oil A Peak 1 Signal: QLEMONC.D\FPD2B.CH ~50-100 ppb of unknown pesticide estimated from FPD response Peak 2 ~125-250 ppb of unknown pesticide estimated from FPD response 5.00 10.00 15.00 20.00 25.00 30.00 35.00 Slide 18
Lemon Oil, Peak 1 Cut Results MS TIC of peak 1 cut FPD2 (P mode) of peak 1 cut 25.50 26.00 26.50 27.00 27.50 28.00 28.50 Slide 19
Peak 1 is Mecarbam Abundance 8000 6000 4000 2000 0 m/z--> Abundance Scan 2653 (27.976 min): QLEMONC1.D (-) 131 97 159 116 65 329 206 296 45 144 178 226 82 192 239 252268283 313 Spectrum of peak 1 40 60 80 100 120 140 160 180 200 220 240 260 280 300 320 340 8000 6000 97 131 #344: Mecarbam 159 Library Match Spectrum: Mecarbam Match Quality 99% m/z--> 4000 2000 0 65 116 329 45 296 144 206 226 177 80 191 252268283 40 60 80 100 120 140 160 180 200 220 240 260 280 300 320 340 Slide 20
FPD1 Screen of Lemon Oil A Signal: QLEMONC.D\FPD2B.CH Peak 2 ~125-250 ppb of unknown pesticide estimated from FPD response 5.00 10.00 15.00 20.00 25.00 30.00 35.00 Slide 21
Lemon Oil, Peak 2 Cut Results MS TIC of peak 2 cut Methidathion, 97% Match Quality FPD2 (P mode) of peak 2 cut 25.00 25.50 26.00 26.50 27.00 27.50 28.00 28.50 29.00 29.50 Slide 22
12 Organophosphorus/sulfur pesticides in 3000 ppm diesel TIC: 3K_10P.D MS TIC 2 10 ppm each 4 5 6 7 11 10 89 12 FPD (P) 1 3 FPD (S) 2 3 4 5 6 7 8 9 Retention time (min) Slide 23
Cut 1 pesticide from 3000 ppm diesel 2 4 5 6 7 89 10 11 12 FPD1 (P) 2 3 4 5 6 7 8 9 Retention time (min) cut Thionazin MS TIC FPD2 (P) Ext Ion 180 SIM Ion 180 6.50 7.00 7.50 Slide 24
Summary Developments in GC hardware in recent years have made Deans switch systems easier to construct, use, and maintain. Single oven, non-cryo systems can often solve the problem 2-D GC is a powerful tool that can be used by itself or combined with other selective techniques to solve difficult separation problems. Slide 25