From Helium to Hydrogen: GC-MS Case Study on SVOCs in Water

Transcription

1 From Helium to Hydrogen: GC-MS Case Study on SVOCs in Water Jessie Butler Alexander N. Semyonov December 13, 2012

2 Helium? It s gone! Not only at Disneyland Resort 2 Helium shortage grounds Mickey at Tokyo Disneyland, Agence France-Presse Nov 27, 2012.

3 Switching to Hydrogen Carrier Gas: Practicalities Hydrogen Carrier Gas Van Deemter Curve Our Position as a Company Safety Considerations Generators vs. Cylinders GC-MS Tuning Hydrocarbon Background Water Spectrum Resolution Target Tuning (DFTPP) GC Inlet and Column Maintenance Mode of Injection Liner Selection Column Selection Performance Linearity & Fit Sensitivity & IDL Spectral Integrity & Library Match Stability & Robustness Before you migrate to hydrogen carrier on your GC-MS 3

4 Carrier Gases: Physical Properties Property He H 2 N 2 Ar Molecular Mass, Da Density, kg/m Diffusion Coefficient, cm 2 /s Viscosity, Pa s u opt, cm/s <10 He H 2 Carrier Gas Density: Less is Better Diffusion Coefficient: More is Better He H 2 * Dynamic Viscosity : Less is Better 4 * Crystal Lattice Density Analogy only, O.Fryazinov; A.Pasko; V.Adzhiev Computer-Aided Design 2011, 43(3)

5 5 Dynamic Viscosity vs. Temperature

6 6 Carrier Gases Efficiencies: Van Deemter Plots

7 Effect of GC Oven Heating Rate: PCB Mix RT: He, 25 C min 1 NL: 2.73E5 TIC MS pcb-h-srm NL: 4.22E5 TIC MS pcb-h-srm H 2, 50 C min No Loss of R s All this time space is intentionally left blank Time (min) 7 Polychlorinated Biphenyls Mix ran by Dirk Claus, Interscience,

8 Effect of Flow Rate C:\chem\...\November29.b\level8.d\level8 11/29/2012 6:06:54 PM RT: Hydrogen 3 ml/min (115 cm/sec) NL: 1.35E8 TIC MS 200ng NL: 3.26E8 TIC MS level8 Hydrogen 1 ml/min (66 cm/sec) Helium 1 ml/min (44 cm/sec) NL: 3.18E8 TIC MS 200nghe1m lflowjbc Time (min) 8

9 Relative Abundance Relative Abundance Peak Shape and Critical Separations RT: H 2, 2 ml/min NL: 5.23E6 m/z= MS level5 RT: H 2 NL: 6.19E6 m/z= MS level He, 2 ml/min NL: 7.26E6 m/z= MS level Time (min) He RT: NL: E7 m/z= MS level Time (min) Indeno[1,2,3-cd]pyrene & benzo[g,h,i]perylene Time (min) Benzo[b&k]fluoranthene 9

10 Thermo Fisher Scientific Position on Hydrogen with GC-MS Hydrogen Kit Required to Run with H 2 Required for H 2 Specifications Includes Hydrogen Sensor Requires 300 L/s Turbo Pump Thermo Scientific Hydrogen Systems ISQ Single Quadrupole GC-MS TRACE 1300 Series GC TSQ 8000 GC-MS/MS Explosion Tested & Certified Upgrades in the Field All existing ISQ GC-MS Systems are either already H 2 capable or are upgradeable with 300 L/s Turbo and H 2 Kit Thermo Scientific DSQ & DSQ II can be used with H 2 at your own risk (no explosion tests) 10

11 ISQ GC-MS Hydrogen Carrier Installation Specifications ISQ Single Quadrupole GC-MS Guaranteed installation specifications with hydrogen carrier gas Choice of either He or H 2 on installation spec sign-off PCI/NCI same S/N! 11

12 ISQ GC-MS Technical Brief - AB

13 Hydrogen Gas Safety Safety Precautions Hydrogen sensor in GC oven Venting hydrogen The risk is minimal Can be estimated & prevented Safety Facts on ISQ GC-MS and TSQ 8000 GC-MS Explosion Tested & Explosion Certified No detaching/flying pieces even IF hydrogen inside goes boom It is really hard in practice to reach explosive limits of hydrogen in the lab space and the GC oven is monitored by the sensor. 13

14 Hydrogen Purity Specifications GC-MS Hydrogen Generator O 2 < 0.01 ppm H 2 O < 1 ppm THC N/A Hydrogen Grade 5.0 UHP O 2 < 1 ppm H 2 O < 3 ppm THC < 0.1 ppm Hydrogen FID Fuel Grade O 2 < 1 ppm H 2 O < 3 ppm THC < 0.5 ppm Hydrogen Grade 6.0 UHP O 2 < 0.1 ppm H 2 O < 0.5 ppm THC < 0.1 ppm 14

15 Hydrogen Generators: Choose the Best 15

16 Understanding Hydrogen Plumbing Gas Filter, triple stage Tubing Stainless steel preferred 1/8 pre-cleaned New tubing is preferred over used with He Filter only need with tanks For removal of water, oxygen and hydrocarbons What you need to know about plumbing up hydrogen to your GC 16

17 Inlet Considerations Maintenance Daily liner replacement No MS maintenance Source is self cleaning Liner selection: 4 mm splitless with glass wool Mode of Injection Split preferred for EPA Method 8270 Reduces time in inlet 17

18 Injection: Hot Needle Split (10:1) Split Injection Customized Injection Parameters With sensitivity of ISQ GC-MS, may run in Split Mode 18

19 Limits on Hydrogen Flow and Column Selection 1 ml/min hydrogen on 0.25 mm 30 m column 1 ml/min hydrogen on 0.18 mm 20 m column 19

20 Vapor Volume CH 2 Cl 2 Split 5 to 1 RT: ml/min, 8 psi: vapor volume 0.5mL NL: 2.12E8 TIC MS level ml/min, 13 psi: vapor volume 0.4 ml NL: 1.55E8 TIC MS 1ng Time (min) 20 Vapor Volume reduced with higher pressures

21 GC-MS Tuning Dealing with HC background ions and water Bake out at 350 C with hydrogen flow at 4 ml/min Mass Resolution: good Shows similar tune to that with helium Target Tuning for DFTPP Special tuning sequence to meet EPA tuning criteria AutoTune if no DFTPP criteria to be met 21

22 Bake-out at 350 C with H 4 ml/min for 1 hr FC-43 n-(c 4 F 9 ) 3 N DFTPP

23 Air Water Spectra: m/z 29 and m/z 19 m/z 18 m/z 19 m/z 28 m/z 29 m/z 18 m/z 28 23

24 Target Tuning for DFTPP Decafluorotriphenylphosphine 24

25 Target DFTPP Tuning Report: He vs. H 2 He H 2 25

26 DFTPP (Decafluorotriphenylphosphine) Spectrum Helium NL: 2.73E6 dftpp4#1315 RT: 5.28 AV: 1 SB: T: {0,0} + c EI Full ms [ ] Hydrogen m/z NL: 4.04E6 DFTPP12#1310 RT: 5.27 AV: 1 SB: T: {0,0} + c EI Full ms [ ] 26

27 Thermo Scientific Target Software Still Viable Product 27

28 Target DFTPP H 2 Tuning Report in Target Software 28

29 Target BFB (4-Bromofluorobenzene) H 2 Tuning Report 29

30 Thermo Scientific TraceFinder 2.1 Software Alternate Software Option 30

31 Ion Ratio Stability for DFTPP 31

32 GC-MS with H 2 : SVOC Performance Linearity: Ave. %RSD = 14.0 EPA Method 8270 list 1 to 200 ppm Dichloromethane 1 µl Spectral Integrity #1 Match to NIST All Target Compounds Sensitivity: Ave. IDL 0.15 ppm Replicates at 1 ppm Robustness Test: 30 replicate injections of 5 % diesel Ave 5.6 % RSD of ISTDs Passed Check std QC (Bracketed at start and end of run and between each ten replicates of samples) Passes QC for EPA Method

33 EPA Method 8270 Performance Mix RT: Helium RT: 5.53 AA: BP: RT: 5.86 AA: BP: RT: 6.90 AA: BP: RT: 7.97 AA: BP: NL: 2.15E7 TIC MS ICIS DFTPP Hydrogen RT: 4.90 AA: BP: RT: 5.27 AA: BP: RT: 6.20 AA: BP: RT: 7.02 AA: BP: NL: 2.69E7 TIC MS ICIS DFTPP11 Peak 1 pentachlorophenol Peak 2 DFTPP Peak 3 benzidine Peak 4 p,p -DDT Time (min) 33

34 Hydrogen vs. Helium Linearity: Ave 14% RSDs ( ppm) H2 %RSD 14 He %RSD 6.4 Compounds with R nitrophenols nitroanilines dinitrophenols 4,6-dinitrophenol 2-methylphenol trichlorophenols dinitrotoluenes hexachlorocyclopentadiene tribromophenol pentachlorophenol butylbenzylphthalate di-n-octylphthalate bis(2-ethylhexyl)phthalate

35 Effect of Solvent Selection with Hydrogen Carrier ethyl acetate,inlet 325 mecl, inlet R2= R2= R2= R2= R2= R2= %RSD of more active compounds reduced when using ethyl acetate vs. dichloromethane 35

36 ISQ GC-MS IDLs for EPA Replicates at 1 ppm 36

37 #1 Matches to NIST Library with Hydrogen Carrier Gas 100 Diethylphthalate Match 918 R. Match level4#2911 RT: 6.25 AV: 1 SB: ,4,6-tribromophenol Match 868 R. Match level4#3089 RT: 6.56 AV: 1 SB: Head to Tail MF=931 RMF= Head to Tail MF=870 RMF= Diethyl Phthalate Isodrin Match 832 R. Match level4#3715 RT: 7.64 AV: 1 SB: Head to Tail MF=894 RMF= Phenol, 2,4,6-tribromo Isodrin

38 TIC of 5% Diesel RT: NL: 6.22E8 TIC MS diesel Time (min)

39 Robustness 30 Injections of 5 % Diesel ,4-dichlorobenzene-d4(6.3%RSD) naphthalene-d8(4.9%rsd) acenaphthene-d10(6.4%rsd) phenanthrene-d10(5.3%rsd) Chrysene-d12(5.5%RSD) perylene-d12(5.3%rsd) Check Standard bracketed between each 10 Diesel samples 39

40 Check Standard % Difference Less Than ±20 % 40

41 Moving To Hydrogen on the GC Side Hydrogen Sensor is Required In GC oven Optional on the hydrogen generator Expect Lower Inlet Pressure Due to viscosity differences of H 2 and He Move to a smaller ID column Solvent Peak Tailing Operate at higher inlet pressure Move to a metal smaller ID column Better heat conductivity allowing for higher GC oven ramp Safer, unbreakable 41

42 Moving to Hydrogen on the MS Side NO MS hardware change required to meet H 2 Installation Specs if Hydrogen Kit is purchased Maintain good vacuum: Extended Capacity (300 L/s) Turbomolecular Pump Torr (@ 1 ml/min hydrogen flow) It is the compression ratio, not pumping speed that matters Higher initial background: Minimized with SS pre-cleaned tubing Grade 5.0 or higher Hydrogen Bake out source at 350 C for one hour with filament on CI Effect on some compounds: Requires linear or quadratic fit Reduced (vs. fast H 2 GC) flow rate of H 2 into MS to minimize self-ci Pressure Dependency: Minimize solvent vapor with smaller ID columns ISQ Off-Axis Pre-Filter Single Quadrupole GC-MS 42

43 Conclusion Successful migration from helium to hydrogen for SVOCs in water analysis U.S. EPA Method 8270 DFTPP tuning criteria met Good linearity for ~80% compounds (Ave. < 14 %RSD) Quadratic fit of others > 0.99 Similar detection and quantitation limits (IDLs: ~0.18 ppm) Very good long-term stability and robustness Requires GC and MS methods tweaking Requires special attention to the chemistry in the ion source and inlet Application chemist support available on Thermo Scientific GC- MS Systems Call us for a quote: gc.gcms.customersupport@thermofisher.com

44 Thank You! Stay Connected with Chromatography Solutions Blog YouTube Facebook Pinterest 44