New developments in thermal desorption for air analysis and fully automated material emission analysis.

Transcription

1 New developments in thermal desorption for air analysis and fully automated material emission analysis. Yunyun Nie GERSTEL GmbH & Co. KG 4 th Stir Bar Sorptive Extraction Technical Meeting September 18-19, 2017

2 TDU began with SBSE ±NaCl Sequential m SBSE SA-SBSE GERSTEL Solutions for material emissions - from formaldehyde to VOCs / SVOCs

3 New development in TD What does 3.5+ mean? For more than 3 Twisters? Legacy tube compatibility (3.5 x ¼ OD tubes) For Standard needs 200 mg Tenax TA sorbent Up to 260 mg Tenax TA (GERSTEL TD 3.5+ tubes) Stainless steel or glass tubes Maximum recovery for air and DHS sampling

4 GERSTEL TD Superior design and performance TD tubes are uniformly heated all the way to the sampling end Shortest possible distance between TD and trap: No valve nor transfer line! Non-selective, cryogenically cooled trap: - No need for selective sorbent in trap - Good recovery for all analytes: Known, unknown, active & SVOCs - All analytes transferred to GC/MS

5 GERSTEL TD tubes In the TD 3.5 +, the tube is heated all the way to the sampling end 8 mm TD tube: Shorter gap = 260 mg sorbent capacity 15 mm Legacy tubes Traditionally, tubes are not heated to the end (cold spot, potential condensation of SVOCs)

6 GERSTEL TD Maximum sensitivity for air and DHS sampling TD can run standard 3.5 tubes or GERSTEL Tubes using the longer heated zone GERSTEL tubes: Up to 25 % more sorbent than traditional tubes; 4 X more than TDU tubes The extra capacity can be used for maximum recovery, lowest LODs and flexible sorbent selection

7 DHS : Dynamic Headspace for TD Purge headspace from vials or DHS L vessels onto GERSTEL tubes Sample volumes: Standard DHS: 10 or 20 ml DHS Large: 250, 500, or 1000 ml Fully automated sampling available for all sizes Larger sorbent bed (= 4 x TDU sorbent bed): Bigger purge volume Improved recovery of VVOCs Wider range of compounds in one run

8 VVOC + VOC Breakthrough Volumes Group Compounds BP [ C] Classification Breakthrough C [L/g Tenax TA]* Aldehyde Hexanal 130 VOC n.a Aliphatic hydrocarbon n-hexane 69 VVOC n.a. Aliphatic alcohol t-butanol 83 VVOC n.a. Acid Formic acid 101 VVOC n.a. TDU tube Calculated C [L] 70 mg Tenax TA TD 3.5+ tube Calculated C [L] 260 mg Tenax TA Aldehyde Propanal VVOC Acid Acetic acid 118 VOC Aldehyde Butanal 75 VVOC Aromatic hydrocarbon Benzene 80 VVOC Acid Butyric acid 164 VOC Aromatic hydrocarbon Toluene 111 VOC Aromatic hydrocarbon p-xylene 138 VOC Aromatic hydrocarbon o-xylene 144 VOC *Source:

9 Peak Response 70 mg Tenax TA sorbent DHS Purge Volume Variation VVOC &VOC Mix using Tenax Sorbent 70 mg Propanal tert-butanol Butanal n-hexane Benzol Toluol Hexanal p-xylol o-xylol VVOC + VOC Mix Sampling_100mL Sampling_200mL Sampling_300mL Sampling_500mL Sampling_700mL Sampling_1000mL Sampling_1500mL Propane and t-butanol: Breakthrough volume < 100 ml No Propanal found at purge volume > 300 ml Compounds from benzene shown: Breakthrough volume > 1500 ml

10 Peak Response 260 mg Tenax TA sorbent Purge Volume Variation VVOC &VOC Mix using Tenax Sorbent 260 mg Sampling_100mL Sampling_200mL Sampling_300mL Sampling_500mL Sampling_700mL Sampling_1000mL 0 Propanal tert-butanol Butanal n-hexane Benzene Toluol Hexanal p-oxylol o-oxylol VVOC+VOC Propanal : Breakthrough volume > 700 ml t-butanol: Breakthrough volume > 300 ml Compounds from Butanal shown: Breakthrough volume > 1500 ml

11 GERSTEL Solutions for Material Emissions from formaldehyde to VOCs and SVOCs Automated Formaldehyde solutions: DNPH-HPLC based PFPH-TD-GC/MS - based Automated VOC/SVOC solutions (TD-GC/MS): Thermal extraction Headspace methods, incl. multi-injection (HIT) Dynamic Headspace (DHS) Micro-scale chamber method (up to 1 L) Workstation, extends the compatibility

12 Micro-scale chamber-td/gc-ms Micro-Scale Chamber, 30 ml - 1 L Air tight, controlled temperature and gas flow/exchange, low analyte background, gas phase sampling onto sorbent tube Screening method, quality control, material development Related to classic chamber method results: µg x m -2 x h -1 Low cost, quick Standard Methods: ISO I2219-3, ASTM D , ASTM WK40293

13 ASTM STP1589 Measurement of Chemical Emissions from Spray Polyurethane Foam Insulation Using an Automated Micro-scale Chamber System Target Compound Abbr. CAS Nr. Discription B.P. [ C] (760 mmhg) Linearity r² 1,1,1,3,3-Pentafluoropropane HFC-245fa Blowing Agent 15.8 / Bis(dimethlyaminopropyl)methylamine DAPA Amine Catalyst Tetramethyliminobispropylamine TMIBPA Amine Catalyst Bis(2-Dimethylaminoethyl)ether BDMAEE Amine Catalyst Pentamethyldiethylene triamine PMDTA Amine Catalyst N,N,N-Trimethylaminoethylethanolamine TMAEEA Amine Catalyst Tris-(1-chloro-2-propyl)phosphate TCPP Fire Retardant C, 200 ml A si BDMAEE si B TMIBPA C TCPP TVOCs SVOCs Fire retardants Amine catalysts Blowing agents

14 Average Emission Factor [µg m-².h-1] Analyzing bigger, more representative samples Example: Open cell SPF Insulation (Polyurethane) BDMAEE (23 C) TMIBPA (65 C) TCPP (23 C) 3 cm 5 cm 8 cm For a defined Surface, the Emission Factors for BDMAEE, TMIBPA and TCPP increase with increasing sample thickness For lower Bp/MW compounds, the effect is more pronounced: BDMAEE shows a 40 % increase both when going from 3 to 5 cm, and from 5 to 8 cm thickness. For TMIBPA and TCPP, there is only a 16 % - 18 % increase.

15 EF [µg/m².h] Workflow ASTM WK Cut the sample seal the chamber adjust the flow rate: 50 ± 5 ml/min operate the micro-scale chamber temperature: 23 ± 2 C wait for at least 30 min for equilibration connect a sorbent tube to the chamber. Re-check the gas flow collect sample for 20 minutes or up to 2 hours HFC-245fa closed-cell SPF 8cm Hour [h] disconnect the sorbent tube from chamber. Analyze with GC-MS repeat steps 10.8 to with addtional sorbent if necessary repeat steps 10.9 to to measure emisions versus time. For example at 4h, 12h, 48h, 72h... + The process is repeated at 60 C to simulate field conditons

16 Determination of CH 2 O and VOCs in Wood-based Products 2,4- Dinitrophenyldydrazine (DNPH) DNPH Derivative (a hydrazone) Sample eluation: 2 ml ACN HPLC parameters: 5 µl injection volume C18-Rreverse Column DAD decetor at 360 nm Compound-DNPH Standard Mix Calibration (HPLC/DAD) LOD Linearity [µg ml -1 ] (R²) (n=5) Linear Range [µg ml -1 ] LOQ [µg ml -1 ] (n=5) Compound Micro-scale Chamber 3 L sampling volume and 2 ml ACN elution Method Detector Limit (MLD) LOD [µg m - ³] (n=5) LOQ [µg m - ³] (n=5) Formaldehyde-DNPH Formaldehyde Acetaldehyde-DNPH Acetaldehyde Acetone-DNPH Acetone Acrolein-DNPH n.d. n.d. Acrolein n.d. n.d. Others-DNPH > 0,9991 n.d n.d. n.d. n.d.

17 Sample Overview (CH2O / VOCs) 6 cm x 9 cm Two sides Stand vertically 1 Liter container OSB (oriented-strand board) MDF (medium-density fiber board) Puzzle floor plate

18 Concentration of Aldehydes and Ketones by DHS L 1L container with 3L sampling volume (µg/m³) Samples OSB 12 mm (6 x 9 cm) two sides MDF 12 mm (6 x9 cm) two sides Hero Bausteine floor plate (6x9cm) two sides, Average (n=4) Compound Formaldehyde Acetaldehyde Acetone Acroleine n.d. n.d. n.d. Propionaldehyde 5.85 n.d. n.d. Crotonaldehyde n.d. n.d. n.d. Butyaldeyhde 6.29 n.d. n.d. Benzalldehyde n.d. n.d. n.d. Valeraldehyde? n.d. n.d. n.d. Isovaleraldehyde? n.d. n.d. o-tolualdehyde? n.d. n.d. n.d. m/p-tolualdehyde? n.d. n.d. n.d. Hexanal n.d. 2,5- Dimethylbenzaldehyde n.d. n.d. n.d.

19 Alternative derivatization agent PFPH Benefits of PFPH [1] More thermally stable and more volatile than the hydrozone derivates of DNPH PFPH elutes before any of its carbonyl derivatives on a nonpolar stationary phase GC column, enabling the use of more derivatization agent. 90 % cost savings relative to using PFBHA No need for further purification Principle Derivatization agent: Pentafluorophenylhydrazine (PFPH) On-Tube loading (Tenax TA) Reaction with formaldehyde (CH 2 O) Forms thermally stable derivate: PFPH-CH 2 O Determined by Thermal Desorption (TD)-GC-MS DNPH N C H H + + H 2 O PFPH CH 2 O PFPH-CH 2 O

20 Determination of Airborne Carbonyls: Comparison of a Thermal Desorption/GC Method with the Standard DNPH/HPLC Method S T E V E N S A I H A N G HO A N D, J I A N Z H E N Y U * Department of Chemistry, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong Sampling tubes loaded with 510 nmol of PFPH on Tenax sorbent effectively collect gaseous carbonyls, including formaldehyde, acetaldehyde, propanal, butanal, heptanal, octanal, acrolein, 2-furfural, benzaldehyde, p-tolualdehyde, glyoxal, and methylglyoxal, at a flow rate of at least up to 100 ml/min. All of the tested carbonyls are shown to have method detection limits (MDLs) of sub-nmol per sampling tube, corresponding to air concentrations of <0.3 ppbv in a 24 L sample. These limits are 2-12 times lower than those obtained using the DNPH/HPLC method. Comparison studies on ambient samples and kitchen exhaust samples have demonstrated that the two methods do not yield systematic differences in concentrations of the carbonyls that are above their respective MDLs in both methods, including formaldehyde, acetaldehyde, acrolein, and butanal. The lower MDLs of the PFPH/GC method also enable the determination of a few more carbonyls in both applications.

21 Limiting PFPH-CH2O background: Effects of air contact with PFPH loaded Tenax TA tube PFPH PFPH-CH 2 O Abundance 2.5e+07 2e e+07 1e Time--> Abundance 2e e+07 1e Time--> Abundance 2.5e+07 2e e+07 1e Time--> Abundance Time--> PFPH TIC: _004.D\data.ms Immediately after PFPH loading PFPH : PFPH-CH2O = 1 : 0.7 After 2.5 hours PFPH : PFPH-CH2O = 1 : 0.9 After 10 days PFPH : PFPH-CH2O = 1 : 2.2 Very small PFPH-CH 2 O derivate peak seen after direct injection into CIS, the derivatization agent is OK!

22 Limiting PFPH-CH2O background: Avoiding air contact by using TSS & DHS for loading Abundance 3.5e+07 3e e+07 PFPH Tube Spiking System (TSS) Background: 1.5 % 2e e+07 1e+07 PFPH-CH 2 O Time--> TIC: _005.D\data.ms Abundance 3.4e e+07 3e e e e e+07 2e e e e e+07 1e Time--> Split50, 200µLPFPH DHS Background: 1.6 % TIC: _007.D\data.ms

23 CH 2 O GERSTEL TD Solutions Step1: DHS loading PFPH Step2: DHS CH 2 O Calibration Or DHS/DHS L sampling CH 2 O Step3: Thermal desorption/gc-ms Automated through Maestro Software, using Prep Sequence Trap Temp.: 20 C Tenax TA Trap Temp.: 20 C Tenax TA+ PFPH Tenax TA + PFPH or Step1: 100µL PFPH Incubation Temp.: 30 C 10µL CH2O Step2 Sample Chamber up to 1000 ml Step3

24 PFPH-CH2O Background (%) Feasibility of the PFPH-TD-GC/MS Solution for CH 2 O monitoring Abundance 100µL PFPH on Tenax TA Storage Study No carryover Time--> Storage Time (h) PFPH-CH 2 O background stable after direct loading, RSD = 4.3%, n=5 Percentage of PFPH-CH 2 O to PFPH Peak area ranges from 0.6 to 2. 5 %. The background level should not exceed this value. The PFPH-CH 2 O background can not be totally eliminated, but can be minimized through the use of TSS or DHS for loading.

25 Peak Area Flow Rate optimization for formaldehyde sampling with respect to reaction kinetics PFPH-CH 2 O flow rate optimization at 50 C 1.0E E E E E E E E E E E Flow rate (ml/min) Trap Temp.: 20 C Tenax TA+ PFPH 10µL CH2O At flow rates > 45 ml/min, the reaction of CH 2 O with PFPH will not be quantitative due to kinetic limitations.

26 peak response Method Validation 6.00E+08 Calibration of CH 2 O using 144 nmol PFPH on-sorbent derivatization (n=5), split 1/ E E E+08 Sampling onto PFPH in excess by a factor of 1.8 relative to the total amount of carbonyls provides > 90 % recovery of carbonyls [1] 2.00E E+08 y = 2E+08x + 9E+06 R² = E Total Amount of CH 2 O (µg) 100 µl PFPH solution new PFPH-CH2O Average (n=6) 4.44E+06 RSD %(n=6) 4.27 DIN LOD (µg) 0.09 LOQ (µg) 0.25 Compound Linear Range (µg) Linear Range (nmol) R² Average RSD % (4 Levels, n=5) CH 2 O

27 Wood sample Abundance Tenax TA: Sampling Volume: 1000 ml Split ratio: 1/10 Time--> Abundance PFPH + Tenax TA: Sampling Volume: 500mL Split ratio: 1/40 Time--> Figure: Chromatograms of plywood sample emissions. Top: using Tenax TA/TD-GC/MS approach, sampling volume 1000 ml at room temp., split ratio 1/10. Bottom: using PFPH/TD-GC/MS aproach, sampling volume 500 ml at room temp., split ratio 1/40. compounds identified: 1.Pentanal, 2. Hexanal, 3. Acetic acid, hexyl ester, 4. Nonanal, 5. Pentafluorobenzene, 6. PFPH, 7. PFPH-formaldehyde, 8. PFPH-pentanal, PFPHhexanal (isomers), 11. PFPH-nonanal

28 CH 2 O Concentration (mg/m³) CH 2 O concentratin (mg/m³) Hexanal Peak Response Power Method: CH2O + VOCs + SVOCs CH 2 O Emission profile of polywood* Emission Profile over Time E E y = e x R² = E E E E Sampling Point (min) 0 0.0E Sampling Point (min) Formaldeyhde Hexanal *polywood:9x6 cm, two sides, surface specific air flow rate [m 3. m 2 h 1 ] =0.278 (based on AgBB criteria) 1) Tenax TA + PFPH + TD-GC/MS: Determination of Formaldehyde and other airborne carbonyl compounds 2) Tenax TA + TD-GC/MS: Determination of VOCs, SVOCs and TVOC TD-GC/MS Process

29 Abundance 2.2e+07 2e e e e e+07 1e Time--> Abundance 2.2e+07 2e e e e e+07 1e Time--> Green Candle sourced from a local store Tenax TA PFPH + Tenax TA CIS -30 C; split ratio: 1/40, sampling volume: 1000mL Nr. Compound 1 Toluene 2 Hexanal (MW: 100) 3 Ethyl 2-methylbutanoate 4 2-Hexenal (MW:98) 5 Isoamyl acetate 6 2-methylbutyl acetate 7 Hexyl acetate 8 Isopentyl isobutyrate 9 Triplal 1 (MW138) 10 Triplal 2 (MW138) 11 Benzyl acetate 12 Ally heptanoate 13 Isoamyl Allylglycolate 14 2-tert-Butylcyclohexanol 15 2-tert-Butylcyclohexanol isomer 16 Alpha-Damascone 17 Allyl Cyclohexylpropionate 18 Isopropyl myristate 19 PFPH (m/z: 155,182,198) Calculated CH 2 O concentration in sampled micro-scale chamber air: mg/m³ 20 PFPH-CH 2 O (m/z: 155,182,210) 21 PFPH-hexanal (m/z: 155,182,280) 22 PFPH-hexanal isomer (m/z: 155,182,280) 23 PFPH-hexenal (m/z: 155,182,278) 24 PFPH-peak9 (m/z: 155,182,318) 25 PFPH-peak10 (m/z: 155,182,318)

30 E-liquids Name Green Apple Irish Fielde 7 Levels Propylene Glycol (PG) % Vegetable Glycol (VG) % Water % Nicotine (mg/ml) Add 5 µl E-Liquid in 10 ml Vial DHS 80 C /150 C + PFPH/Tenax TA Tube

31 Abundance Nicotine 3e e+07 2e e+07 1e+07 PG VG PFPH PFPH-CH 2 O E-Liquid (7 leaves) PG/VG:55/35, Nicotine:18(mg/mL) Time--> 0 Abundance 2.8e e e e+07 2e e e e e+07 1e Time--> Abundance 2.6e e e+07 2e e e e e+07 1e Time--> PG VG Nicotine E-Liquid (Irish Fielde) PG/VG: 50/41, Nicotine: 9 (mg/ml) Vaniline Triacetin PG VG Diacetin E-Liquid (Green Apple) PG/VG: 50/41, Nicotine: 0 (mg/ml)

32 Multi Material Emission Solution Platform Tenax TA PFPH Automated Formaldehyde solutions DNPH-HPLC PFPH-TD-GC/MS Automated VOC/SVOC Solution using TD-GC/MS Thermal extraction Headspace method Micro-scale chamber method Workstation, extended compatibility

33 Thank you for your attention! Questions?