Atmospheric Pressure Gas Chromatography: Background & Applications. Jody Dunstan MS Systems Evaluation, Manchester 2011 Waters Corporation 1

Transcription

1 Atmospheric Pressure Gas Chromatography: Background & Applications Jody Dunstan MS Systems Evaluation, Manchester 2011 Waters Corporation 1

2 What is APGC? 2011 Waters Corporation 2

3 What is APGC Waters APGC is an optional ion source for Xevo and SYNAPT systems that provides a highly sensitive GC/MS, MS/MS & HDMS capability. Ionisation by APGC is soft (cf. APCI) and molecular ions are readily detected. Fragmentation can be induced (CID) to provide information for structural elucidation. On HDMS SYNAPT instruments, molecular ions and fragments can be separated by shape and size (ion mobility) enabling the separation of some isobaric species (structural isomers). It is very easy to swap between APGC and ElectroSpray (or other ion source) without venting the instrument in a matter of minutes Waters Corporation 3

4 Source and Ion Chamber 2011 Waters Corporation 4

5 How Does it Work? 2011 Waters Corporation 5

6 APGC How it works Corona Pin Ionization Chamber Heated Transfer Line Mass Spec Atmospheric Region Capillary GC Column 2011 Waters Corporation 6

7 APGC How it works Analyte Molecules are ionised after GC elution and directed to the mass analyser Corona discharge at needle creates plasma N 2 make-up gas delivered through transfer line interior Mass Analyser GC Oven N 2 meets GC eluent flow at transfer line tip 2011 Waters Corporation 7

8 The Waters Xevo TQ-S 2011 Waters Corporation 8

9 How did we increase sensitivity? Xevo TQ-S Larger sampling orifice 2011 Waters Corporation 9

10 Ion Block Design Sampling cone aperture Increased to 0.8mm diameter o Approx 5x increase in gas/ion flow New ion block design No supplemental pumping All ions (and gas) enter StepWave guide o Approx 200x increase in gas flow o Up to 200x increase in ion flux Waters Corporation 10

11 Designed to deal with problems associated with a larger sampling orifice Electric Field Diffuse Ion Cloud Maximising signal Maximising robustness 2011 Waters Corporation 11

12 APGC Ionisation Modes & Spectral Characteristics 2011 Waters Corporation 12

13 Mechanism of Ionization (I) Charge Transfer Corona Pin e - N 2 2N 2 M 2e - N 2 + N 4 + M + M + M Dry source conditions Favored by relatively non-polar compounds 2011 Waters Corporation 13

14 Mechanism of Ionization (II) Protonation M Corona Pin N 2 + N 4 + H 2 O H 2 O + H 3 O + +OH [M+H] + H2O Modified source conditions eg. with water or methanol present Favored by relatively polar compounds 2011 Waters Corporation 14

15 Comparison between fragmentation in EI+ and APGC. Endosulphan NIST Spectrum M +. APGC Spectrum 2011 Waters Corporation 15

16 Chromatographic Performance Flow Rate. 0.01µg/ml BF Std CSL_200306_ TOF MS EI Da cps % EI GC TOF 5uL Injection Faster run possible due to atm pressure source and higher res MS EI+ 0 ANAPGC240409TEST Time TOF MS AP Da cps AP+ % APGC on TOF 1uL Injection ~ 10X higher response for APGC 0 Time 2011 Waters Corporation

17 Example Data: Dioxins & Furans Waters Corporation 17

18 Dioxin Analysis Dioxins and dioxin-like compounds (DLC) are by-products of various industrial processes, and are commonly regarded as highly toxic compounds that are environmental and persistent pollutants (POPs). Analysis must comply with legislative requirements. EPA1613 in USA and (EC) No 152/2009 & 252/2012 in Europe. The Gold Standard for analysis is magnetic sector MS (e.g. Waters AutoSpec). Magnetic sector MS instruments are complex and difficult to use and require significant user training. Modern Tandem MS/MS instrument offer high sensitivity, flexibility and ease of use Waters Corporation 18

19 Calibration Standards Congener Concentration (pg/µl) Name 1/10 CSL* CSL CS0.5 CS1 CS2 CS3 CS4 TCDD TCDF PCDD PCDF HxCDD HxCDF HpCDD HpCDF OCDD OCDF Waters Corporation 19

20 Peaks Areas, Signal:Noise & Repeatability Peak are and Signal to Noise (1/10 CSL) RT Name Std. Conc (pg/µl) Quantify Area Qualify Area S/N TCDD TCDF PCDD PCDF PCDF HxCDD HxCDD HxCDD HxCDF HxCDF HxCDF HxCDF HpCDD HpCDF HpCDF OCDD OCDF Repeatability (n=10) Name Mean STDEV % RSD Response TCDD TCDF PCDD PCDF PCDF HxCDD HxCDD HxCDD HxCDF HxCDF HxCDF HxCDF HpCDD HpCDF HpCDF OCDD OCDF %RSD < 10% 2011 Waters Corporation 20

21 1/10 Dilution of CSL Standard (10 fg TCDD on column) 2011 Waters Corporation 21

22 TCDD native and 13 C transitions (CSL) _ fg TCDD CSL Std 100 TCDD F1:MRM of 8 channels,ap+ 322 > e+004 % min _ fg TCDD CSL Std 100 TCDD F1:MRM of 8 channels,ap+ 320 > e+004 % min _ fg TCDD CSL Std TCDD C F1:MRM of 8 channels,ap+ 332 > e+007 % 0 min _ fg TCDD CSL Std TCDD C F1:MRM of 8 channels,ap+ 334> e+007 % min 2011 Waters Corporation 22

23 TCDD Calibration Summary with Ion Ratio Name Type Std. Conc (pg/µl) RT Area IS Area Response 1º Ratio (Actual) 1º Ratio (Pred) Deviation from Ion ratio (%) _002 Standard _003 Standard _004 Standard * _005 Standard _006 Standard _007 Standard _008 Standard _009 Solvent _011 QC _012 QC _013 QC _014 QC _015 QC _016 QC _017 QC _018 QC _019 QC _020 QC Deviation < 20% * pg/µl standard was determined to be definitive ion ratio 2011 Waters Corporation 23

24 Calibration Examples Compound name: TCDD Correlation coefficient: r = , r^2 = Calibration curve: * x Response type: Internal Std ( Ref 1 ), Area * ( IS Conc. / IS Area ) Curve type: Linear, Origin: Exclude, Weighting: 1/x, Axis trans: None Compound name: TCDF Correlation coefficient: r = , r^2 = Calibration curve: * x Response type: Internal Std ( Ref 3 ), Area * ( IS Conc. / IS Area ) Curve type: Linear, Origin: Exclude, Weighting: 1/x, Axis trans: None Response r 2 = >0.999 Response r 2 = > pg/µl Compound name: PCDD Correlation coefficient: r = , r^2 = Calibration curve: * x Response type: Internal Std ( Ref 5 ), Area * ( IS Conc. / IS Area ) Curve type: Linear, Origin: Exclude, Weighting: 1/x, Axis trans: None -0.0 pg/µl Compound name: HxCDD Correlation coefficient: r = , r^2 = Calibration curve: * x Response type: Internal Std ( Ref 11 ), Area * ( IS Conc. / IS Area ) Curve type: Linear, Origin: Exclude, Weighting: 1/x, Axis trans: None Response r 2 = >0.999 Response r 2 = > pg/µl pg/µl Waters Corporation 24

25 Calibration Summary Compound %RSD Calibration RRF TCDD 3.3 TCDF 7.9 PCDD PCDF PCDF HxCDD HxCDD HxCDD HxCDF HxCDF HxCDF HxCDF HpCDD HpCDF HpCDF 3.3 OCDD 1.8 OCDF 8.3 Coeff. Of Name Determination TCDD >0.999 TCDF >0.999 PCDD > PCDF > PCDF > HxCDD > HxCDD > HxCDD > HxCDF > HxCDF HxCDF > HxCDF HpCDD > HpCDF > HpCDF >0.999 OCDD >0.999 OCDF Waters Corporation 25

26 Example Data: Polychlorinated biphenyls (PCBs) 2011 Waters Corporation 26

27 PCB 105 Spectra PCB vs APGC NIST Spectrum APGC Spectrum 2011 Waters Corporation 27

28 Calibration Standard Information Concentration Name CS1 CS2 CS3 CS4 CS5 13 C 1,2,3,4-TCDD PCB PCB PCB PCB PCB PCB PCB PCB A 13 C analogue for each PCB was used as an internal standard, 13 C TCDD was used as a syringe standard Waters Corporation 28

29 Chromatography Examples Pentachloro- PCB from CS3 PCB 123 PCB Waters Corporation 29

30 CS1 Standard, Peaks Areas & Signal:Noise Compound Rt (min) Peak Area S:N (rms) PCB PCB PCB PCB PCB PCB PCB PCB Compound %RSD PCB PCB PCB PCB PCB PCB PCB PCB fg on column, 1 µl injection %RSD < 12% 2011 Waters Corporation 30

31 Example Data: Brominated Flame Retardants (PBDEs) 2011 Waters Corporation 31

32 Sensitivity - PBDE 1 ng/ml Name Pred.RT Trace 1º Trace Area S/N BDE > > BDE > > BDE > > BDE > > BDE > > BDE > > Octa BDE > > BDE > > BDE > > Waters Corporation 32

33 Linearity Example BDE 28 & BDE 100 Compound name: BDE 28 Correlation coefficient: r = , r^2 = Calibration curve: * x Response type: External Std, Area Curve type: Linear, Origin: Exclude, Weighting: Null, Axis trans: None Response r 2 = ng/ml Compound name: BDE 100 Correlation coefficient: r = , r^2 = Calibration curve: * x Response type: External Std, Area Curve type: Linear, Origin: Exclude, Weighting: Null, Axis trans: None Response r 2 = ng/ml Waters Corporation 33

34 Example Chromatography Samples MAT 42 & Waters Corporation 34

35 Both the Xevo TQ and Xevo TQ-S tandem quadrupole mass spectrometers are equipped with RADAR an information rich data acquisition approach. In RADAR mode MRM data can be collected in parallel to the collection of spectral MS data, in both positive and negative ion modes. This can be done with little or no impact on the quality of the MRM data. In RADAR you can accurately quantify target compounds while at the same time track other sample matrix components, arming you with a greater depth of knowledge about your sample. It is important to recognise that RADAR is only possible because of the instrument s ability to rapidly alternate between MS, MS/MS, positive and negative ion modes without compromising performance Waters Corporation 35

36 RADAR Example Data MAT42 PBDE MRM transitions MS Scan BPI trace 2011 Waters Corporation 36

37 Untargeted Compound Found in RADAR Scan Br H Br Br H O H H O H Br H Br Isotope Model H H Br Measured Mass spectra at peak Rt (molecular ion cluster magnified) and a comparison between the measured and theoretical isotope patterns 2011 Waters Corporation 37

38 What s Next? Persistent Organic Pollutants (POPs) analysis. Further collaborations with industry experts. Testing of a wide variety of matrices and comparison with existing gold standard techniques. What else can APGC offer? What are ideal applications that would work well with higher flow rates or different column dimensions? Explore the full potential of HDMS systems. e.g. hydrocarbon analysis using ion mobility Waters Corporation 38

39 Acknowledgments Prof. Bert van Bavel MTM Research Centre, Örebro University, Sweden. Brock G. Chittim, Wellington Labs, Canada. Petr Kukučka, Recetox, Czech Republic. Wim Broer, NOFALAB, The Netherlands Waters Corporation 39