GC/MS 의 원리 및 이론

1. GC/MS의 원리 및 이론 부경대공실관 VOCs/냄새분석실

2. What is Mass Spectrometry? Measure the masses of individual molecules & atoms which are converted into gas phase ions in terms of their mass to charge ratios convert into gas (chromatographic separation) Inlet Source Analyzer Detector Data System ionization sort ions by m/z solid liquid gas mass spectrum

3. ▣ GC의 기본 구성과 기능

4. ▣ 시료주입기와 주입방법 1. 섬광기화 직접법 2. 섬광기화 분할법(split) 3. 섬광기화 비분할법(splitless) 4. 섬광기화 냉각법 5. 온도프로그래밍 기화법(PTV) 6. 냉각 온-컬럼 주입법(OCI) 7. 기타

5. ▣ 컬럼오븐 분리도와 머무름 재현성 향상을 위해서 1. 설정온도와 실제온도의 일치 2. 최저 및 최고 작동 온도의 범위의 확장 3. 오븐의 가온·냉각 속도가 정확 4. 오븐 온도의 평형 시간의 단축 5. 설정된 온도가 주기적인 변동없이 안정

6. ▣ 컬럼온도에 따른 분리도 30℃ 등온분석 100℃ 등온분석 30~200℃ 승온분석

7. ▣ 검출기의 종류 1. 이온화 검출기(ionization detector) 불꽃이온화 검출기(flame ionization detector;FID) 열이온화 검출기(thermionic ionization detector;TID) 광이온화 검출기(photo ionization detector;PID) 전자포획 검출기(electron capture detector;ECD) 2. 물리적 성질 검출기(bulk physical detector) 열전도도 검출기(thermal conductivity detector;TCD) 3. 광학 검출기(optical detector) 불꽃광도 검출기(flame photometric detector;FPD) 원자방출 분광 검출기(atomic emission detector;AED)

8. What is the Mass Spectrum? # of ions mass to charge ratio

9. Diverse Mass Spectrometric Systems Inlet + Source :시료도입 및 이온화 방법에 따라 EI, EI/DIP, CI, DCI, FD, FI, TI, FAB(LSIMS), LD, ESI, APCI, MALDI, GC-MS, LC-MS, CE-MS, etc. Analyzer :질량분석관에 따라 Sector, TOF, Q(quadrupole mass filter, 2D-Q) Quadrupole IT(ion trap, 3D-Q), ICR (FTMS) Hybrid MSs (Sector-TOF, QqTOF, TOF-TOF, QqQ, IT-TOF, etc)

10. Choice of MS Method I Volatile Non-volatile Reservoir Inlet GC/MS DIP FAB, LD, MALDI ESI/APCI (but should be soluble in ESI/APCI compatible solvents) Thermally Stable Thermally labile GC/MS FAB, APCI ESI, MALDI

11. Choice of MS Method II

12. Information from Mass Spectrometry Molecular Structure Molecular Weight & Elemental Composition From fragmentation molecular ion→ molecular mass (M+Na)+=897 → M=874 accurate mass → elemental composition 897.4976 → C48H74O14Na isotopic distrib’n→ elemental composition source of the sample Information from MS Quantitation Non-covalent Interaction Non-covalent adduct (Ab-Ag, host-guest)

13. Advantage of MS detector • Information of chemical structure • Identification of target compound • Determination of molecular weight • High sensitive and rapid analysis

14. Identification MS Spectrum m/z Chromatogram Retention time

15. Configuration of GCMS Data Store Interface Mass Spectrometer Ion source box Gas Chromatograph

16. Flow Chart of GC-MS Sample Inlet System Mass Analyzer Ion Source Detector GC Direct Signal Processor Vacuum System Print Out

17. MS analyzer • Magnetic sector type (sector type) • Quadrupole type • Time of flight type (TOF type) • Ion Trap type Quadrupole type of GCMS is very popular.

18. Schematic of a Quadrupole MS system Generation Selection Introduction Detection

19. Hardware structure of QP/MS

20. Ion Source Box- Increased ionization efficacy - Ion source box Conventional ion source Filament QP2010 ion source • High luminosity ion source Interface

21. Ion Source Box Extractor : This device can draw ion generated into the ion source box. from GC QP2010 To QP

22. Optimum adjustment of the Lens system QP X Software can optimize lens voltage in order to introduce more ions to Quadrupole.

23. Quadrupole Rod- Minimize losses in transit to the Quadrupole - Pre Rod From ion source To detector Main Rod Specific ion only can be passed by the electronic field into Quadrupole Rod which is controlled by PC.

24. Vacuum system • - Minimize losses in transit to the Quadrupole - • rotary pump • Dual turbo pumping system • turbo molecular pump [260 L/sec X 65 L/sec]

25. Low-noise Dynode multiplier- Increased detection of created ions - • Low noise detector unit Conversion dynode EM Detector

26. High Sensitivity QP-2010 QP-5050 Octaflouronaphthalene, 1pg : S/N > 60 Octafluoronaphthalene, 1pg : S/N > 30

27. Modes of Ionization • EI : Electron Impact • Hard Ionization, High Energy • Structural information • CI : Chemical Ionization • Soft Ionization, Low Energy • Molecular weight information

28. Ionization techniques available for GC/MS • Electron Impact Ionization (EI) • Positive Chemical Ionization (PCI) • Negative Chemical Ionization (NCI)

29. Electron Impact Ionization (EI) filament + + QP e- e- e- e- e- + + Sample from GC Fragment ion

30. Electron Impact Ionization (EI) • Thermal electrons (ca. 70 eV) hit molecules and ionize them. • Ample fragment ions = ample structural information “finger print” EI spectrum Methylstearate M.W. 298

31. Positive Chemical Ionization (PCI) QP filament from gas cylinder -CH4 e- CH5+ C2H5+ e- e- CH4 H+ e- e- -C2H4 [M+1] Sample from GC

32. Positive Chemical Ionization (PCI) • Reagent gas molecules are ionized first. Sample molecules are ionized mainly by “proton transfer”. • Quasi molecular ions easily produced useful for molecular weight verification. + PCI spectrum Methylstearate M.W. 298

33. Fragment Molecular weight Comparison of EI and PCI EI mode PCI mode

34. Reagent Gas Sample Sample Negative Chemical Ionization - NCI - filament NCI for highest sensitivity for electrophilic compounds e- e- e- e-

35. e- Negative ion formation by electron capture (associative resonance capture) • MX + e- (~0 eV) MX-. H CH4 + + CH4 CH4 CH3 CH4 CH4 - e- MX MX X: positive electron affinity part

36. Advantages of negative chemical ionization Ion formation by electron capture • High sensitivity Close to GC-ECD sensitivity • High selectivity

37. Application fieldfor negative chemical ionization • Environmental • chlorinated pesticides • phosphorus pesticides • PCB etc. • Life science • Drugs, steroids, bile acids

38. Measurement Mode • Scan Mode • SIM Mode (Selected Ion Monitoring) (Quantitative) (Qualitative) mass number mass number [Scan] [SIM] Time Time

39. Scan Mode 152 72 54 m/z TIC : Scan Mode Retention time

40. SIM Mode Higher Sensitivity than Scan Mode. For quantitation purpose m/z=72 m/z=152 m/z=54 Retention time

41. Adjustment of MS • All adjustment of the instrument can be carried out by Windows Software. • Sensitivity adjustment • Resolution adjustment • Correction of mass number • Correction of relative intensity

42. MS Tuning PFTBA(perfluorotributylamine) is use for MS tuning.

43. CF3 -CF2 -CF2 -CF2 -N -C4F9 C4F9 PFTBA relative m/z intensity 69 100.0 131 26.0 219 32.0 414 2.0 502 2.0 614 0.4

44. Direct Injection Mode (DIP)

45. Operational Precaution for GCMS

46. Operation Precautions • Sample • Pretreated sample • Know amount of components in the sample • Used the smallest appropriate sample volume • For unknown, screen on GC first • Tools • Wear sanitary gloves when performing any • work on IS or analyzer housing • Wipe/clean all the tools with acetone to • minimize the background noise

47. Operation Precautions • Column • Avoid wide bore, thick film & dirty column. • Use the recommended standard sample and • column to evaluate the system performance. • Perform preventive maintenance frequently • to minimize problems.

48. Sample Pretreatment • Filtration • Centrifuge • Extraction • HSG • Dynamic HS (Purge & Trap) • Static HS

49. Extraction • LLE • isolating organic compounds from • aqueous samples • SPE • isolating organic compounds from • aqueous samples • Soxhlet • extracting nonvolatiles and • semivolatiles from solid samples • Sonication • extracting nonvolatiles and • semivolatiles from solid samples

50. Sample Clean-up • Acid-base partition • Sulfur clean-up • Adsorption column chromatography • Alumina clean-up • Silica gel clean-up • Florisil clean-up • GPC