Beyond Static Headspace: Automated techniques to extend the limits of headspace analysis for VOCs

1. Beyond Static Headspace:Automated techniques to extend the limits of headspace analysis for VOCs Edward Pfannkoch Director, Technology Development Gerstel Inc.

2. MPS 2 Advanced Headspace Capabilities

3. Advanced Headspace Injection Modes with the MPS 2 Autosampler • Static Headspace (SH) • Multiple Headspace Sample Enrichment (MHSE) • MPS-Hot Injection and Trapping Mode (HIT) • Dynamic Headspace Sampling (DHS) • Full Evaporation Dynamic Headspace Sampling (FEDHS)

4. Static Headspace Analysis • Equilibration of the solid/liquid samples in crimped vials at a constant temperature

5. Static Headspace Analysis • Straightforward technique for liquids • Solid samples can present challenges • Limited sensitivity • Limited vial options • Large inj volume = broad early peaks • Distribution coefficient can bias results

6. Multiple Headspace Sample Enrichment (MHSE) Several samples are taken from the same vial. The analytes are cyro-focused or focused on a packed bed liner in the PTV liner during multiple sample Introductions. Benefit: Improved detection limit

7. CIS 4 (PTV injector)

8. MHSE of an Herbal Based Liqueur

9. MPS-HIT Mode Hot Injection and Trapping

10. TDU TDU tube Thermal Desorption Unit - TDU No Transfer line ! Cooled Injection System - CIS

11. MPS-HIT Mode New Versions of Maestro (1.4.9.16 and up) Headspace and SPME Injections can be made into the TDU CIS can be cooled for trapping or heated for direct transfer to the column For SHS, allows trapping of analytes in cold inlet while avoiding discrimination of higher boiling components For SPME, allows trapping/refocusing of volatile analytes from the fiber which can help sharpen early eluting peaks Allows quick change from thermal desorption to SPME or SHS without removing the TDU

12. HIT with CIS Hot HIT with CIS Cold SLH with CIS Hot SLH with CIS Cold Peak #1 = 1,1-Dichloroethene Peak #26 = 1,2-Dichlorobenzene

13. Dynamic Headspace (DHS)

14. Dynamic Headspace Option for MPS 2

16. Tube Types

17. Incubation temperature: 40 °C (Coffee powder) 25 °C (Shower gel) Incubation time: 5 min Purge flow: 20 mL/min Extraction time: 10 min (Coffee powder, shower gel) Trap temperature: 25 °C Trap: TDU tube filled with Tenax-TA TDU temperature program: 30°C; 720°C/min; 280°C (8 min) TDU pneumatic setting: Splitless CIS temperature program: -100°C; 12°C/s; 280°C (8 min) CIS pneumatic setting: solvent vent (Split 10:1) Parameters

18. 100 mg coffee powder – Relative Peak Areas • % • 100 • 90 • 80 • 70 Peak areas in % (DHS = 100 %) • 60 • 50 • 40 • 30 • 20 • 10 • 0 DHS SPME 2-Methylbutanal 2,3-Pentadione Methylpyrazine HS Dimethylpyrazine 1-Hydroxy-2-propanone Furfural Furfurylacetat Ethyldimethylpyrazine Furfurylalcohole 5-Methyl-2-furancarboxaldehyde 2-Methoxyphenol

19. GC TD-GC SHS DHS HS vial volume: 10-20 mL Sample volume: 1-15 mL HS vial volume: 10-20 mL Sample volume: 1-15 mL SHS and DHS SHS is equilibrium technique which is controlled by the partitioning coefficient of the solutes between two phases (headspace and sample matrix). DHS prevents the establishment of an equilibration state, causing more of the volatile dispersed in the sample matrix to leave the sample and pass into the headspace.

20. GC TD-GC SHS DHS HS vial volume: 10-20 mL Sample volume: 1-15 mL HS vial volume: 10-20 mL Sample volume: 1-15 mL SHS and DHS These techniques are generally biased toward recovering more volatile compounds or more hydrophobic compounds.

21. Full Evaporation Technique (FET) FET provides more uniform recovery for a variety of compounds and sample matrix independent analysis. “Matrix independent headspace gas chromatographic analysis. The full evaporation technique” M. Markelov, J. P. Guzowski, Analytica Chimica Acta, 276 (1993) 235. FET is the headspace technique of introducing a small amount of sample (mg level) and vaporizing the analytes in the headspace vial at elevated temperatures (typically at 100 ºC), without having to rely on establishing equilibrium between two phases. GC 100℃ A few μL～

22. Fragrance profiling by FEDHS In 2009, Hoffman et al demonstrate fragrance profiling of consumer products by FEDHS-GC-MS [7]. A. Hoffmann Adsorbent packed tube Purge gas in Shower gel (MeOH blend) The FEDHS-GC-MS method enables quantitative extraction of fragrance compounds across a wide range of volatility, leading to results that are closer to the actual fragrance composition than those obtained with other commonly used analysis technique such as simultaneous distillation/extraction (SDE). 80 ℃ 8 μL 7) A. Hoffmann et al, GERSTEL AppNote 8/2009.

23. In this study, we demonstrate uniform enrichment of a wide range of odor compounds in aqueous samples by FEDHS-GC-MS. The optimized purge condition allow complete vaporization of 100 μL of an aqueous sample, and drying it in an adsorbent packed tube, while recovering odor compounds and leaving the low volatile matrix behind. FEDHS Adsorbent packed tube Purge gas in 80 ℃ 100 μL 8) N. Ochiai, K. Sasamoto, A. Hoffmann, K. Okanoya, in preparation.

24. Influence of purge volume on the water residue in the Tenax TA trap 100 μL of water is calculated to be 1.8 L of water saturated gas at 40ºC of trap temperature. Water management is very important step in FEDHS because large amount of water up to 100 μL can be condensed and accumulated in the adsorbent trap. The purge volume of more than 2.6 L was required to eliminate water. This might be due to re-condensation of a part of water vapor in the vent line of the DHS module at ambient temperature. 8 7 6 5 GC-TCD response (a.u. x 1010) 4 3 2 1 0 1300 1500 1700 1900 2100 2300 2500 2700 2900 3100 3300 Purge volume (mL)

25. Comparison of recovery between conventional DHS, HS-SPME, and FEDHS for test odor compounds in water at 100 ng/mL HS-SPME DHS DHS WS < log 3.0 (mg/L) 100 Sample: 1 mL Temp: 80ºC Fiber: CAR/DVB/PDMS Incub. time: 20 min Ext. time: 30 min Sample: 1 mL DHS Temp: 80ºC Purge vol.: 0.35 L Sample: 1 mL DHS Temp: 25ºC Purge vol.: 3 L WS > log 3.0 mg/L 80 60 Recovery (%) 40 20 0 Damascenone Butyrolactone Phenethyl acetate Phenethyl alcohol Nonalactone 2,5-Dimethyl 2-Acetyl thiazoleol Citronellol Guaiacol pyrazine Nonanal Linalool Indole log WS 5.65 (mg/L) log WS 4.51 (mg/L) log WS 4.34 (mg/L) log WS 3.86 (mg/L) log WS 3.18 (mg/L) log WS 2.85 (mg/L) log WS 2.83 (mg/L) log WS 2.11 (mg/L) log WS 2.04 (mg/L) log WS 1.08 (mg/L) log WS 4.40 (mg/L) log WS 3.08 (mg/L)

26. Comparison of recovery between conventional DHS, HS-SPME, and FEDHS for test odor compounds in water at 100 ng/mL FEDHS HS-SPME DHS DHS 100 Sample: 1 mL DHS Temp: 25ºC Purge vol.: 3 L Sample: 0.1 mL DHS Temp: 80ºC Purge vol.: 3 L Sample: 1 mL Temp: 80ºC Fiber: CAR/DVB/PDMS Incub. time: 20 min Ext. time: 30 min Sample: 1 mL DHS Temp: 80ºC Purge vol.: 0.35 L 80 60 Recovery (%) 40 20 0 Damascenone Butyrolactone Phenethyl acetate Phenethyl alcohol Nonalactone 2,5-Dimethyl 2-Acetyl thiazoleol Citronellol Guaiacol pyrazine Nonanal Linalool Indole log WS 5.65 (mg/L) log WS 4.51 (mg/L) log WS 4.34 (mg/L) log WS 3.86 (mg/L) log WS 3.18 (mg/L) log WS 2.85 (mg/L) log WS 2.83 (mg/L) log WS 2.11 (mg/L) log WS 2.04 (mg/L) log WS 1.08 (mg/L) log WS 4.40 (mg/L) log WS 3.08 (mg/L)

27. Gerstel DHS Conditions Trap Temperature: 30 deg C Incubation Temperature 80 deg C Tenax TA

28. FEDHS of Strawberry-Banana Juice

29. FEDHS of Carrot Juice

30. FEDHS of Cranberry Juice

31. FEDHS of Mango Coconut Water

32. SBSE of Coconut Water

33. SBSE of Flavored Coconut Water

34. Applications • Analysis of off odor compounds in apple juice by FEDHS-GC-MS • Analysis of flavor markers in vitamin drink

35. Apple Juice • 14 2-Hexenal • Cis 3-Hexenol • 2-Hexenol • 1-Hexanol • 2-Acetyl furan • Butyrolacton • Benzaldehyde • Methyl heptenone • Hexylacetate • Cis 3-Hexenyl acetate • Nonanal • Dihydromethyljasmonate • Butanal • Ethyl acetate • Aceticacid • 1-Butanol • Ethyl propionate • Propylacetate • 3-Methyl butanol • 2-Methyl butanol • Ethyl butyrate • Hexanal • Butyl acetate • Ethyl 2-methylbutyrate • Furfural 17 6200000 6000000 5800000 5600000 5400000 5200000 5000000 4800000 3 4600000 4400000 4200000 4000000 3800000 3600000 3400000 3200000 3000000 2800000 2600000 2400000 13 2200000 14 2000000 1800000 * 1600000 1400000 1200000 1000000 800000 * 16 600000 400000 4 200000 * 2.00 4.00 6.00 8.00 10.00 12.00 14.00 16.00 18.00 20.00 22.00 24.00 26.00 28.00 11 8 2 * * 25 9 12 7 10 19-23 1 5 24 6 15 18

36. Apple Juice with Off-Flavor Overlay with reference (black trace), zoom 4000000 * 3500000 * 3000000 * 2500000 2000000 1500000 1000000 500000 0 17.00 18.00 19.00 20.00 21.00 22.00 23.00 24.00 25.00 26.00 27.00 28.00 29.00 g-Undecalactone * g-Decalactone

37. Multi Vitamin Juice Sulfur compounds (Markers for Pineapple Juice Content) Limonene 9000000 8500000 8000000 Methyl 3-(methylthio)-propanoate 7500000 7000000 6500000 Ethyl 3-(methylthio)-propanoate 6000000 5500000 5000000 a-Terpineol 4500000 4000000 3500000 3000000 2500000 2000000 1500000 1000000 500000 2.00 4.00 6.00 8.00 10.00 12.00 14.00 16.00 18.00 20.00 22.00 24.00 26.00 28.00 * * * * *

38. Multi Vitamin Juice Sulfur compounds, extracted ion chromatogram (m/z 61, 74, 134, 148) 75000 70000 65000 60000 Ethyl 3-(methylthio)-propanoate m/z 61, 74, 148 55000 Methyl 3-(methylthio)-propanoate m/z 61, 74, 134 50000 45000 40000 35000 30000 25000 20000 15000 10000 5000 0 18.00 18.50 19.00 19.50 20.00 20.50 21.00 21.50

39. Multi Vitamin Juice Low in Pineapple Juice Content 75000 70000 65000 60000 55000 50000 45000 40000 35000 30000 25000 20000 15000 10000 Methyl 3-(methylthio)-propanoate m/z 61, 74, 134 5000 0 18.00 18.50 19.00 19.50 20.00 20.50 21.00 21.50 Ethyl 3-(methylthio)-propanoate m/z 61, 74, 148

40. Conclusion Using the MPS 2 autosampler with Maestro software allows automation of the following techniques that can overcome many of the limitations inherent to static headspace sampling: • Multiple Headspace Sample Enrichment (MHSE) • Improves detection limit • MPS-Hot Injection and Trapping Mode (HIT) • Improves peak shapes • Dynamic Headspace Sampling (DHS) • Improves detection limit • Full Evaporation Dynamic Headspace Sampling (FEDHS) • More uniform enrichment of analytes • SBSE for analysis of nonpolar analytes at ultralow levels

41. Analysis ConditionsDHS Incubat Temp 50°CIncubat Time 0 minAgi On Time 10 sAgi Off Time 1 sAgi Speed 500 rpm Purge Volume 4000 mLPurge flow 100 mL/minTrap Temperature 30°C Dry Volume 0 mLDry Flow 0 mL/minDrying Temperature 30°C Transfer Temp 150°C

42. Analysis ConditionsTDU Tube Type Carbotrap B/X Pneumatics Mode splitlessSample Mode sample remove Temperature 30°C (0.1 min); 720°C/min; 280°C (3 min)Transferline Temp. 320°C

43. Analysis ConditionsCIS 4 LN2 - Cooling Liner Type Glasswool Carrier Gas HeliumPneumatics Mode solvent ventingVent Flow 30 mL/minVent Pressure 51 kPa until 0.0 minSplitflow 20 mL/min @ 1.0 min Temperature -80°C (0.1 min); 16°C/sec; 150°C; 12°C/sec; 240°C (2 min)

44. Analysis ConditionsGC Model Agilent 7890 Column Rxi-624Sil MS (Restek); 30 m x 0.25 mm x 1.4 µm Mode constant flow, 1.0 mL/min Temperature 40°C (2 min); 5°C/min; 100°C; 10°C/min; 300°C (10 min)