Triple Quadrupole Gas Chromatography-Mass Spectrometry/Mass Spectrometry Re-imagined: Increased Simplicity and Productivity
•Download as PPTX, PDF•
4 likes•3,027 views
Key Learning Objectives: • Identify emerging triple quadrupole Gas Chromatography-Mass Spectrometry/Mass Spectrometry (GC-MS/MS) technology designed to address increasing regulatory demands and requirements • Explore potential time savings in sample prep, method development/transition, and data analysis • Demonstrate how to optimize the GC-MS/MS workflow from sample prep to sample analysis to automated data analysis Overview: Regulatory lab requirements continue to drive detection limits lower with an ever increasing list of compounds to analyze. These requirements also demand greater precision at these lower limits. Triple quadrupole GC-MS/MS is a viable option for enhanced analysis and increased productivity with an emphasis on simplicity. We discuss emerging trends and technologies designed to ensure that laboratories are well-equipped to address these increased demands with minimal investment in training and method development. Find out how you can adopt triple quadrupole GC-MS/MS technology in your laboratory using existing methods and source parameters in most instances while requiring less sample prep and enjoying the benefits of automated data analysis for increased simplicity and productivity. For more information: www.thermoscientific.com/tsq8000
Recommended
More Related Content
What's hot
What's hot (20)
Viewers also liked
Viewers also liked (16)
Similar to Triple Quadrupole Gas Chromatography-Mass Spectrometry/Mass Spectrometry Re-imagined: Increased Simplicity and Productivity
Similar to Triple Quadrupole Gas Chromatography-Mass Spectrometry/Mass Spectrometry Re-imagined: Increased Simplicity and Productivity (20)
More from Chromatography & Mass Spectrometry Solutions
More from Chromatography & Mass Spectrometry Solutions (20)
Recently uploaded
Recently uploaded (20)
Triple Quadrupole Gas Chromatography-Mass Spectrometry/Mass Spectrometry Re-imagined: Increased Simplicity and Productivity
- 1. 1 The world leader in serving science Increased Simplicity and Productivity Triple Quadrupole GC-MS/MS Re-imagined
- 2. 2 Tough challenges faced in the laboratory • High sample loads/short deadlines • Keeping sample analysis costs down with more and more challenging LODs and matrices • Integrating and maintaining new methods and technologies into production workflows to remain competitive
- 3. 3 What„s required... • Realization of the productivity advantages of high performance GC- MS/MS • Minimizing the impact of adoption and implementation to current laboratory operations
- 4. 4 Triple Quadrupole GC-MS/MS is an essential part of a cost- effective, high productivity analytical method in today’s laboratory
- 5. 5 Many laboratories are already investing in and exploring GC- MS/MS as a tool to obtain a competitive edge in their analyses
- 6. 6 GC-MS/MS – What‟s so special? • Low detection limits • Reduced sample preparation • Consolidated analytical methods • Faster, automated data processing ...it is a high selectivity technique...
- 7. 7 Selectivity in a method McLafferty circa. 1980
- 8. 8 Method performance requirement • Target compounds • Matrices • Sensitivity Method performance requirement
- 10. 10 ...then instrument detection... Step1–extraction Step2-cleanup(1st) Step3-cleanup(2nd) Step4-GC-MSdetection(singlequadSIM) Total method selectivity Method performance requirement
- 11. 11 Analytical Benefits for Single Quadrupole GC-MS • Robust • Run more samples between cleaning • Sensitive Precision • Accurate and reproducible results at the lowest levels • Unknown Analysis • Full scan for unknown library searches • Alternating full scan/SIM for unknowns and low level analysis • Flexibility • Switch quickly between dedicated EI and CI sources • Easy to Use and Maintain
- 12. 12 Full Scan/SIM Methodology for Drinking Water
- 13. 14 Challenging Samples for Single Quadrupole GC-MS • Matrix Challenges • Concentration challenges • Difficult to prove contamination Gamma BHC Methiocarb Mevinphos
- 14. 15 ...what about GC-MS/MS?... Step1–extraction Step2-cleanup(1st) Step3-cleanup(2nd) Total method selectivity Step4-GC-MS/MSdetection(TriplequadSRM) Method performance requirement
- 15. 16 Use GC-MS/MS to reduce clean-up... Step1–extraction Total method selectivity Step2-GC-MS/MSdetection(TriplequadSRM) Method performance requirement
- 16. 17 Use GC-MS/MS to consolidate methods... Step1–extraction Total method selectivity Step2-GC-MS/MSdetection(TriplequadSRM) Method 1 performance requirement Method 2 performance requirement Method 3 performance requirement
- 17. 18 Use GC-MS/MS to consolidate methods... Step1–extraction Total method selectivity Step2-GC-MS/MSdetection(TriplequadSRM) Consolidated multi-residue method
- 18. 19 What will GC-MS/MS do for my lab? High selectivity • Possibility the reduce selectivity in sample preparation • Reduced sample prep steps creates a more generic sample prep method – more compounds & matrices • Consolidated GC-MS methods due to high performance – buffer against requirements • Compressed chromatography possible • Easy peak evaluation – auto- integrators
- 19. 20 Step 1: Ions are produced in the source
- 20. 21 Step 2: Ions are focused in the s-shaped prefilter
- 21. 22 Step 2: Ions focused by prefilter, removing neutrals
- 22. 23 Step 3: Ions are isolated by molecular weight in Q1
- 23. 24 Step 3: Ions are isolated by molecular weight in Q1
- 24. 25 Step 4: Ions further fragmented in collision cell (With same mass as analyte)
- 25. 26 Step 4: Ions further fragmented in collision cell
- 26. 27 Step 5: Unique ions to analytes chosen in Q3
- 27. 28 Only unique fragments to analyte detected Step 5: Unique ions to analytes chosen in Q3
- 28. 29 AutoSRM Overview 1) Precursor ion selection 2) Product ion selection 3) Collision energy optimization SRMCreationWorkflow
- 29. 30 Step 1 – Pick Your Precursor Ions
- 30. 31 Step 1 – Pick Your Precursor Ions
- 31. 32 Step 1 – Pick Your Precursor Ions
- 32. 33 Step 2 – Pick Your Product Ions
- 33. 34 Step 2 – Pick Your Product Ions
- 34. 35 Step 3 – Optimize Your Transitions
- 35. 36 Step 3 – Optimize Your Transitions
- 36. 37 Export from AutoSRM to Instrument Method
- 37. 38 Timed-SRM Method Overview Acquisition Windows centered around retention time and Window
- 38. 39 Timed-SRM Method Overview Acquisition windows allowed to overlap
- 40. 41 Timed-SRM Advantages Acquisition Windows Segmented SRM Timed SRM
- 41. 42 Timed-SRM Advantages • Removes wasted dwell time • Allow higher overall dwell times • Leads to higher sensitivity Wasted Dwell Time
- 42. 43 Timed-SRM Advantages • Peaks centered in acquisition window • No peak elutes near acquisition break • Allows for retention time shift (e.g. due to heavy matrix)
- 44. 45 Timed-SRM from Thermo Scientific TSQ 8000 GC-MS Screenshot of a section of the analytical run showing the “acquisition map” automatically created by the TSQ™ 8000 System using t-SRM.
- 45. 46 Calibration Curves • All calibration curves correlation coefficients greater than 0.99 • Example calibration curve for Cyfluthrin, R2 = 0.9996
- 46. 47 Transitions for Pesticides from PAR ver 2 • SRM peaks at 4 ppb from Terbacil (left, 161.1 > 88.0, CE 15 V) and Alachlor(right, 188.1 > 130.1, CE 25 V) • SRM peaks at 4 ppb from Tolylfluanid (left, 238.1 > 137.1, CE 15 V) and Pyridaben (right, 309.1 > 147.1, CE 15 V)
- 47. 48 The world leader in serving science A Second Level of Selectivity Structure and Mass Defect
- 48. 49 Thermo Scientific TSQ Quantum XLS Ultra – HyperQuad™ Technology Inside Patented HyperQuad technology meets with GC/MS for the first time to create highest performing GC Triple on the market 6 mm hyperbolic precision quads allow excellent ion transmission at standard resolution as well as opportunity to use enhanced mass resolution to 0.1 Da peak width Effective pre-cursor ion filtering with strongly reduced matrix interference Improved signal/noise & quantitative precision
- 49. 50 U-SRM: Two Modes of Selectivity •Ultra selective-Single Reaction Monitoring (U-SRM) •Offers a unique opportunity to increase selectivity using triple quadrupole. •Combination •Increased Q1 mass resolution •MS/MS Structural based selectivity •For use when standard SRM does not provide enough selectivity m/z Increased mass resolution Structural selectivity (MS/MS)
- 50. 51 Precursor Ion Selection Q1 (Standard SRM mode) •At standard mass resolution precursor selection •Q1 = 0.7 Da FWHM •Higher probability that interfering species are transmitted to the collision cell with the target compound mass •These matrix interferents are often orders of magnitude higher than target compounds •If they are not completely discriminated against in by CID then the resulting product ion detection can have a higher background noise present Matrix components transmitted through Q1 during SRM Q1= 218.9 m/z (0.7 Da res.) Q1 Transmission Window Q1= 0.7Da 21921 7 22 1
- 51. 52 219 Precursor Ion Selection Q1 (U-SRM mode) HyperQuad does not allow matrix through through Q1 during U-SRM • When operated in U-SRM mode, the TSQ Quantum XLS Ultra narrows the pre-cursor mass window to <0.2Da •This increased resolution allows the HyperQuad to discriminate against common matrix component masses for targets showing a large enough Δmass defect. •This allows for better collision cell performance and robustness as well as reducing chemical noise •Lindane carries a Δmass defect and can be isolated from matrix in this example Q1= 0.1Da 219217 221 Q1= 218.86 m/z (0.1 Da res.)
- 52. 53 U-SRM: Effect of Increasing Q1 Resolution •Real life effect of the lindane example… •Lindane isomers in green tea •As Q1 resolution is increased into the ultra range signal/noise ratio increases dramatically IncreasingQ1resolution IncreasingSignal/Noise 0.1 Da 0.4 Da 0.7 Da
- 53. 54 U-SRM in action • PCB 28 in industrial soil sample at ca.100fg (ASE extraction with no clean- up) • Continuum full scan spectrum shows background removed with HyperQuad at increased resolution contocpSCAN003 #1594-1597 RT: 13.68-13.69 AV: 4 SM: 7B NL: 4.04E7 T: + p EI Q1MS [200.000-300.000] 255.0 255.2 255.4 255.6 255.8 256.0 256.2 256.4 256.6 256.8 257.0 257.2 m/z 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 RelativeAbundance XLSULTRA_NPV_OCP00016_110329102653 3/29/2011 10:26:53 AM RT: 13.33 - 15.12 SM: 7G 13.4 13.6 13.8 14.0 14.2 14.4 14.6 14.8 15.0 Time (min) 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 RelativeAbundance RT: 13.69 14.54 14.4614.30 14.64 14.68 14.7214.40 14.16 14.7713.73 14.24 14.94 15.02 14.09 14.05 14.89 13.96 13.94 13.81 13.56 NL: 1.05E5 TIC F: + c EI SRM ms2 255.960 [185.965-185.975] MS XLSULTRA_NPV_OC P00016_110329102 653 SRM (Q1 0.7Da) 0.7 Da 256 m/z Q1 precursor selection 2,4,4'-Trichlorobiphenyl
- 54. 55 U-SRM in action • PCB 28 in industrial soil sample at ca.100 fg (ASE extraction with no clean- up) • Continuum full scan spectrum shows background removed with HyperQuad at increased resolution. • Dramatically improved detection using U-SRM C:XCALIBUR...contocpSCAN004 4/14/2011 5:27:58 PM contocpSCAN004 #1469-1471 RT: 13.68-13.69 AV: 3 SM: 7B NL: 3.02E6 T: + p EI Q1MS [200.000-300.000] 255.0 255.2 255.4 255.6 255.8 256.0 256.2 256.4 256.6 256.8 257.0 257.2 m/z 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 RelativeAbundance contocpSCAN003 #1594-1597 RT: 13.68-13.69 AV: 4 SM: 7B NL: 4.04E7 T: + p EI Q1MS [200.000-300.000] 255.0 255.2 255.4 255.6 255.8 256.0 256.2 256.4 256.6 256.8 257.0 257.2 m/z 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 RelativeAbundance XLSULTRA_NPV_OCP00011_110329074139 3/29/2011 7:41:39 AM RT: 13.33 - 15.12 SM: 7G 13.4 13.6 13.8 14.0 14.2 14.4 14.6 14.8 15.0 Time (min) 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 RelativeAbundance RT: 13.69 NL: 3.21E3 TIC F: + c EI SRM ms2 255.960 [185.965-185.975] MS ICIS XLSULTRA_NPV_OCP 00011_110329074139 XLSULTRA_NPV_OCP00016_110329102653 3/29/2011 10:26:53 AM RT: 13.33 - 15.12 SM: 7G 13.4 13.6 13.8 14.0 14.2 14.4 14.6 14.8 15.0 Time (min) 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 RelativeAbundance RT: 13.69 14.54 14.4614.30 14.64 14.68 14.7214.40 14.16 14.7713.73 14.24 14.94 15.02 14.09 14.05 14.89 13.96 13.94 13.81 13.56 NL: 1.05E5 TIC F: + c EI SRM ms2 255.960 [185.965-185.975] MS XLSULTRA_NPV_OC P00016_110329102 653 U-SRM (Q1 0.1Da) Matrix interefent transmitted in standard mode (0.7Da) but rejected during U-SRM (0.1Da) precursor selection PCB 28 Precursor mass 2 55.96 m/z selected 0.1Da0.7Da SRM (Q1 0.7Da) 0.7 Da 0.1 Da
- 55. 56 Environmental: Polychlorinated Biphenyls (PCBS) XLSULTRA_NPV_OCP00017_110329105955 3/29/2011 10:59:55 AM RT: 13.17 - 16.75 SM: 7G 13.2 13.4 13.6 13.8 14.0 14.2 14.4 14.6 14.8 15.0 15.2 15.4 15.6 15.8 16.0 16.2 16.4 16.6 Time (min) 0 50 100 0 50 100 0 50 100 0 50 100 RelativeAbundance 0 50 100 0 50 100 RT: 14.04 AA: 725579 SN: 97 RT: 14.35 AA: 37646 SN: 280 RT: 14.78 AA: 201199 SN: 229 RT: 15.03 AA: 140023 SN: 185 RT: 14.38 AA: 94563 SN: 88 RT: 16.03 AA: 24964 SN: 94 RT: 16.03 AA: 26376 SN: 160 NL: 1.01E5 TIC F: + c EI SRM ms2 255.960 [185.965-185.975] MS XLSULTRA_NPV_OCP00017_11 0329105955 NL: 1.53E5 TIC F: + c EI SRM ms2 257.960 [185.965-185.975] MS ICIS XLSULTRA_NPV_OCP00017_11 0329105955 NL: 1.37E4 TIC F: + c EI SRM ms2 289.920 [219.935-219.945] MS ICIS XLSULTRA_NPV_OCP00017_11 0329105955 NL: 7.06E4 TIC F: + c EI SRM ms2 291.920 [219.935-219.945] MS ICIS XLSULTRA_NPV_OCP00017_11 0329105955 NL: 1.01E4 TIC F: + c EI SRM ms2 323.880 [253.905-253.915] MS ICIS XLSULTRA_NPV_OCP00017_11 0329105955 NL: 1.42E4 TIC F: + c EI SRM ms2 325.880 [255.905-255.915] MS ICIS XLSULTRA_NPV_OCP00017_11 0329105955 XLSULTRA_NPV_OCP00011_110329074139 3/29/2011 7:41:39 AM RT: 13.17 - 16.75 SM: 7G 13.2 13.4 13.6 13.8 14.0 14.2 14.4 14.6 14.8 15.0 15.2 15.4 15.6 15.8 16.0 16.2 16.4 16.6 Time (min) 0 50 100 0 50 100 0 50 100 0 50 100 RelativeAbundance 0 50 100 0 50 100 RT: 13.69 AA: 5479 SN: 859 RT: 13.70 AA: 5485 SN: 862 RT: 14.37 AA: 4122 SN: 1454 RT: 14.36 AA: 1393 SN: 393 RT: 16.05 AA: 2033 SN: 352 RT: 16.04 AA: 3693 SN: 412 NL: 3.21E3 TIC F: + c EI SRM ms2 255.960 [185.965-185.975] MS ICIS XLSULTRA_NPV_OCP00011_11 0329074139 NL: 2.87E3 TIC F: + c EI SRM ms2 257.960 [185.965-185.975] MS ICIS XLSULTRA_NPV_OCP00011_11 0329074139 NL: 2.74E3 TIC F: + c EI SRM ms2 289.920 [219.935-219.945] MS ICIS XLSULTRA_NPV_OCP00011_11 0329074139 NL: 1.02E3 TIC F: + c EI SRM ms2 291.920 [219.935-219.945] MS ICIS XLSULTRA_NPV_OCP00011_11 0329074139 NL: 1.54E3 TIC F: + c EI SRM ms2 323.880 [253.905-253.915] MS ICIS XLSULTRA_NPV_OCP00011_11 0329074139 NL: 2.53E3 TIC F: + c EI SRM ms2 325.880 [255.905-255.915] MS ICIS XLSULTRA_NPV_OCP00011_11 0329074139 Tri, Tetra, Penta PCBs 100 fg in Contaminated land (industrial soil) sample Standard SRM ( Q1=0.7 Da) TSQ Quantum XLS Ultra U-SRM ( Q1=0.1Da )
- 56. 57 Environmental: Pesticides Endrin 1pg in contaminated land sample ran both in SRM (Q1 0.7 amu) and U-SRM (Q1 0.1 amu) U-SRM SRM C:Xcalibur...XLSULTRA_NPV_0104OCP048 4/2/20117:39:50 PM RT: 16.93 - 17.25 SM: 3G 16.95 17.00 17.05 17.10 17.15 17.20 Time (min) 0 20 40 60 80 100 0 20 40 60 80 100 0 20 40 60 80 100 0 20 40 60 80 100 NL: 1.68E5 m/z= 190.43-191.43 F: + c EI SRM ms2 262.910 [190.925-190.935, 192.925-192.935] MS XLSULTRA_NPV_0104OCP0 48 NL: 1.83E5 m/z= 192.43-193.43 F: + c EI SRM ms2 262.910 [190.925-190.935, 192.925-192.935] MS XLSULTRA_NPV_0104OCP0 48 NL: 1.25E4 m/z= 190.43-191.43 F: + c EI SRM ms2 262.910 [190.925-190.935, 192.925-192.935] MS ICIS xlsultra_npv_0104ocp031 NL: 1.86E4 m/z= 192.43-193.43 F: + c EI SRM ms2 262.910 [190.925-190.935, 192.925-192.935] MS ICIS xlsultra_npv_0104ocp031 XLSULTRA_NPV_OCP00015_110329095349 3/29/2011 9:53:49 AM RT: 15.48 - 17.07 SM: 7G 15.5 15.6 15.7 15.8 15.9 16.0 16.1 16.2 16.3 16.4 16.5 16.6 16.7 16.8 16.9 17.0 Time (min) 0 10 20 30 40 50 60 70 80 90 100 RelativeAbundance 0 10 20 30 40 50 60 70 80 90 100 RelativeAbundance RT: 16.56 AA: 28533 SN: 31RMS RT: 15.95 AA: 29627 SN: 31RMS 16.59 16.56 16.71 16.89 16.8416.65 16.7715.95 16.30 16.5016.38 16.23 16.43 16.0615.85 16.08 15.77 NL: 1.74E4 m/z= 175.47-176.47 F: + c EI SRM ms2 245.950 [175.965-175.975] MS ICIS XLSULTRA_NPV_OCP000 15_110329095349 NL: 7.78E3 m/z= 245.45-246.45 F: + c EI SRM ms2 317.940 [245.945-245.955] MS XLSULTRA_NPV_OCP000 15_110329095349 XLSULTRA_NPV_OCP00013_110329084745 3/29/2011 8:47:45 AM RT: 15.48 - 17.07 SM: 7G 15.5 15.6 15.7 15.8 15.9 16.0 16.1 16.2 16.3 16.4 16.5 16.6 16.7 16.8 16.9 17.0 Time (min) 0 10 20 30 40 50 60 70 80 90 100 RelativeAbundance 0 10 20 30 40 50 60 70 80 90 100 RelativeAbundance RT: 16.56 AA: 12784 SN: 708RMS RT: 15.95 AA: 7444 SN: 412RMS RT: 16.86 AA: 380 SN: 22RMS RT: 16.67 AA: 198 SN: 19RMS RT: 16.52 AA: 129 SN: 14RMS 16.56 15.95 16.53 16.6216.4116.11 16.2315.85 16.76 16.7916.3616.03 16.91 NL: 6.83E3 m/z= 175.47-176.47 F: + c EI SRM ms2 245.950 [175.965-175.975] MS ICIS XLSULTRA_NPV_OCP000 13_110329084745 NL: 1.16E3 m/z= 245.45-246.45 F: + c EI SRM ms2 317.940 [245.945-245.955] MS XLSULTRA_NPV_OCP000 13_110329084745 U-SRM SRM o,p-DDE & p,p-DDE 100fg in contaminated land sample ran both in SRM (Q1 0.7 amu) and U-SRM (Q1 0.1 amu)
- 57. 58 • New technology • Sample through-put • Time savings • Lower detection limits • Triple Quadrupole GC-MS/MS provides selectivity with flexibility • Advanced Triple Quadrupole GC-MS/MS can deliver two modes of selectivity • Increased resolution • Structural selectivity through MS/MS Conclusion
- 58. 59 Thank You for Your Attention! Questions? Stay connected with us Twitter @ChromSolutions Chromatography Solutions Blog http://chromblog.thermoscientific.com/blog YouTube http://www.youtube.com/ChromSolutions Facebook http://www.facebook.com/Chromatography Solutions Pinterest http://pinterest.com/chromsolutions/
Editor's Notes
- It is our pleasure to speak to you today regarding the use of current GC/MS technology and how it can help your lab increase both performance and productivity in order to meet the ever evolving requirements of your sample analysisWe will begin by looking at some of the driving forces behind the need for enhanced instrument performanceWe will then explore some of the operating principles and background of GC/MS techniques and begin to define were each technology fits into the lab based on instrument capabilities We will also review some specific instrument features and functions that helps us achieve better analytical performance and some tools that will assist in transition to more enhanced GC/MS techniquesAnd finally look to how the instruments and tools can help you achieve greater performance and enhanced results ultimately increasing productivity in the lab by looking at some specific applications.
- When you are working in a laboratory there are a lot of things to think about. First, you need to think about the samples, what are they and how many. Next is how soon must they be extracted and when is the data needed for the reports. What are the detection limits? And how do you maintain the methods that you are running, what if you are asked for new compounds, how do they get added to these methods?
- The good news there is a lot of help available. There are a lot of article published from all over the globe from people that are in the same situations. There are also new technologies that are available that ease much of the burdens in the lab. Triple Quadrupole GC-MS/MS systems and new software tools are available for just such problems faced in the lab.
- Triple quadrupole GC-MS/MS provides the ability to meet and exceed current regulatory requirements in all types of matrices. The selectivity and sensitivity provided by this technology allows the instrument to grow with the laboratory. Specific software tools will be needed to make the transition from current instrumentation to triple quads more seamless and allow you to be more productive.
- We see this migration from single quads to triple quads for specific analyses happening all over the world. This seems to happen for a few reasons. Regulatory requirements never seem to get any easier, in fact we continue to get more difficultThe number of compounds always seems to be increasing. This is especially true in pesticide analysis where new compounds are developed constantly. This is also seen in drugs of abuse and petrochemical, among others.There is an ever increasing number of samples that need to be tested.There are many more reasons but the biggest and most important reason triple quadrupole GC-MS/MS systems are being adopted by laboratories is economics. It is simply less expensive for this technology with some new tools that we will review to do some of the most challenging methods you perform.
- There are a few things that make triple quads so special.They can provide very low detection limitsThey may allow you to reduce sample preparationIt may be possible to combine several of your current methods in to one.The automated data processing may be faster and more reliable because you are only “looking” for specific compounds at specific times.Triple quadrupole GC-MS/MS systems are highly selective. They can find the target compounds in heavy matrix.
- Let’s take a little time to compare techniques and use signal to noise ratio to explain one reason why triple quads may work better for specific methods. Here signal is the intensity that you will get from a specific detector. The noise is from the chemical noise from the sample and other noise in the system. To simplify our discussion we will assume the noise comes from the matrix. The signal/noise ratio, seen on the green line, is the measure of selectivity. It shows you how selective the instrument and method will be for specific compounds.
- Now that we have the graph let’s start using it.Here we see a specific method requirement. There are some challenges here. First we need to think on how can we get to this level of selectivity and detection limits for this method. There are a few ways that we do this.We can call this the method performance requirement. (purple bar)When we start to look at the example method we see that not a whole lot of selectivity required to achieve the detection of the required compounds Now think of the other variables at play –The sample matrix Required sample prepRequired detection level (or sensitivity). In order to achieve our method performance requirements we need to include these considerations
- Step one is extraction. Next we may need some level of clean up. Some samples may need even more clean up. All of these sample preparation steps will get us closer to meeting the method performance requirements. We can see a typical series of extraction and clean-up steps applied to the sample to get us were we need to beThe extraction procedure provides1 - matrix removal(noise) &2 - target compound recovery (signal increase) Thereby increasing the selectivity of the method combining this effect with the instrument (click) provides adequate signal detection for this type of sample Enough chemical and mechanical noise removal to detect the compounds at the required detection levels
- Now we can use a single quadrupole GC-MS to get us the rest of the way to meet these method requirements.
- Single quadrupoles are in many ways considered the standard GC-MS system. They are in just about every lab that uses GC-MS as an analysis technique. Single quadrupole systems have several very desirable attributes. Look for systems that are:Robust and can run a large number of samples between cleaning. Cleaning should be a quick and easy process.In general single quads are sensitive instruments, especially when run in SIM. Make sure the system is also precise at those low levels. It doesn’t do a lot of good if you can see a low level but it can’t be done repeatedly. That tends to throw off your ability to quantitate to low levels.This technology is great for finding unknowns. Single quads are the go to instrument for library searchable spectra. Look for a system that will allow for full scan to look for unknowns while still providing low level analysis in SIM. Alternating full scan/SIM techniques can give you the low level analysis with unknown screening in a small inexpensive package.Flexibility is also important. Single quads are asked to do a lot. The latest tools can allow you to ask the system to do even more, adding capabilities to your lab.
- To demonstrate the benefits of using full scan/SIM analysis, we’ll look at this volatiles analysis of drinking water. Here we see the first part of the full scan method run from 47- 300 amu and the second part from 35 to 300 amu range to avoid problems as stated in the method requirements. Later in the analysis we see the alternating full scan/SIM data. The collection of SIM data enables the analysis down to lower concentrations for these three compounds. All of this is completed within the same analytical run and eliminates the need to run the sample twice, once in full scan and again in SIM for the compounds with very low detection limits.
- Single quads are great systems and they remain some of the most important instruments in the lab. However, they do run into challenges that are very difficult to deal with. These challenges become even more difficult when you think about the time that is needed to review this type of data and the number of samples that keeps backing up in the lab.
- Now let’s consider triple quad GC-MS/MS. If you keep the same level of sample prep the triple quad will provide significantly more selectivity than this current method requires. You might be looking at this and say, wait why would I need a triple quad to provide such a high level of selectivity for this method if the current method does not require it. You actually partially answered your own question. Method requirements change over time and this will give you flexibility to cut time and cost in other parts of your specific laboratory workflow.
- Furthering this example, we now remove the sample clean-up steps. The selectivity may go down for the complete method because some of the matrix remains. We just saved a significant amount of time. We also still have more than enough selectivity for this method. This allows for future requirements changing and for additional work to be done on this method.
- Now let’s consider other possibilities. Chances have more than one method that is run on a particular instrument. There are different methods needed for different reasons. You might have different matrices, all with different pesticides. You might have different classes of drugs. You might have different soil and water samples from different locations. All of these different methods may have different lists of compounds with slightly different criteria. In the past you would have had to split up these methods because you do not want to waste time on every sample making it perfect for every compound in all lists. With the triple quadrupole GC-MS/MS you may be able to combine these because the system can more than meet selectivity requirements for each one of these methods.
- This brings up the opportunity of method consolidation one of the key strategies for improving laboratory efficiency and ultimately improving productivityEssentially we are opening the door for a single sample preparation method to cover multiple target compounds and matrices at one time.Again, this is all enabled by the selectivity of the triple quadThe triple quad’s selectivity has supported a more generic sample preparation as well as the required performance to be able to bring these separate methods into a single consolidated method
- It is the selectivity of the instrument that drives these benefits. The way to measure selectivity is signal to noise ratio.Selectivity allows for a reduction in sample preparation. It is quite likely that a generic sample preparation procedure can be used that is useful for more compounds and more matrices.It also allows consolidated methods that are efficient for high productivity analysisFaster chromatography will also be possible because the triple quadrupole is very selective for compounds from the matrix and from other compounds. If there is a coelution you will not see the additive interference that is seen on a single quadrupole.Since the instrument is selective for a specific compound at a specific time the baseline will be “clean”. This allows for interferent free detection and fast data processing because nothing gets in the way.
- Now that we know why we would want to use this technique let’s explore how the technique works. If we at least some understanding how a triple quadrupole system works we are in a much better position to understand the resulting data.We start in the GC-MS/MS source. This is where the ions are first created. Using a filament the system ionizes compounds as they elute from the GC column. We also impart a lot of energy to other molecules, like He. This is what becomes the excited neutrals. Since they are neutral there is no electronic field in the system that can control them, they fly everywhere in the manifold including toward the detector.
- Next, in the case of the TSQ 8000 there is a heated S shaped ion guide. This is an RF only ion guide that directs the ions that we created in the source to the analytical rods that do the first mass to charge separation.
- It is also the place where the neutrals are removed. It is most important to remove the neutrals as soon as possible so they do not cause problems in the analytical rods or the fragmentation process in Q2. Since the excited neutrals are removed at the beginning they will no longer cause any problems, like elevated baseline, in the analysis.
- The first quadrupole, called Q1 is where the ions are separated based on their mass to charge ratio. In the case of GC-MS this is most commonly the same as the molecular weight of the ion. Most ions are singly charged in GC-MS.
- All of the ions are removed except those ions you have chosen to continue to Q2.
- In Q2 the ions that have been isolated are fragmented. They fragment based on their structure. If there are other compounds of the same nominal mass but different structure they will produce different fragments.
- Once the fragmentation process begins the product ions continue through Q2. The goal is to get sufficient fragmentation for a good population of product ions.
- After the ions have been fragmented in Q2 they move to Q3. While in Q3 specific product ions are selected. All of the other ions are removed.
- The final ions are then directed into the detection system. In this case they are directed to a dynode and back up to the multiplier. All of this taken together is called SRM, Selected Reaction Monitoring. In Q1 we select one mass to charge ratio. In Q2 we reaction those ions to fragment into product ions. In Q3 we monitor the specific product ions for that compound. If we do this more than once it has been termed multiple reaction monitoring or MRM.
- It is all about the analyzer built into the instrument. Even quadrupoles can provide enhanced mass resolution, if dedicated quadrupole rods are used.The quadrupole systems shown here are extra long, and precision machined rods. These hyperbolic rods allow a more precise control of the mass separation process. The result is an enhanced mass resolution that offers mass peak widths of only 0.1 Da peak width, compared to the 10-fold wider mass peak width in standard instruments. In addition the 50% larger radius gets more ions in, and provides more sensitivity.
- With the U-SRM mode on the TSQ quantum XLS ULTRA two modes of selectivity get combined in one GC-MS/MS instrument.First the increased mass resolution in Q1 separates the target precursor ion efficiently from the isobaric background, so no intereferences occur in the collision cell with prodcut ions generated.Secondly, we combine with the known structural selectivity process of the triple quadrupole.These tools for increased analyte selectivity are available for these cases when regular MSMS selectivity in the wide mode fails.
- We see here the situation with Lindane as the target analyte, buried within high matrix peaks. Typically in real life sample matrix is million fold more intense than the target analytes.Even a narrow mass window of 0.7 Da around the precursor ion 219 allows a lot of matrix to interefere in the collision cell.
- Using the U-SRM mode of the TSQ Quantum XLS Ultra the selectivity of the analyzer changes significantly.The ultra-narrow mass peak window on only 0.1 Da peak width separates the Lindane precursor very efficiently from the sourrounding matrix compounds. The matrix compounds are now excluded from getting into the collision cell, and the possibility of interferences is significantly reduced.
- This is a real example applied for the compounds Lindane in green teaAs the mass resolution increases during SRM, so does the signal/noise ratio resulting in clean detection
- What’s happening on the quad?...Here is another example of a heavy matrix sample with PCB 28 as the target compound (using SRM) with a 0.7 Da peak widthThe mass peak on the right is representing what the Q1 “sees” during SRM. This is real empirical data acquired in continuum mode.We can just about detect the peak in SRM mode but the matrix is limiting us here
- If we increase mass resolution (using U-SRM)We do not transfer interference to the collision cellThe result is a much cleaner detection of the target.
- Extending the previous example to more congeners for PCBs.Left side: standard SRMRight side: U-SRM with easy detection and all confirmatory ion ratios in place
- PesticidesSame story between standard and U-SRMEndrin & DDE
- So let‘s conclude from this presentation.- A high selectivity is the foundation of high quality analytical resultsSelectivity provided by the mass analyzer allows the use of less selective and short sample prep method, which is typically for pesticides the Quechers method for 100s of pesticides. We measure the selectivity on a mass spectrometer using the S/N value in a matrix sample The way it works on a GC triple quad like the TSQ Quantum XLS Ultra is manyfold: - by enhanced mass resolution - by the structural selectivity of the collision process - and finally the combination of both in one instrument, which we call the U-SRM