Ross McCulloch Arturo Álvaro Carballido

Transcription

1 Coupling Atmospheric Pressure Photoionization (APPI) with Differential Mobility Analysis (DMA) Mass Spectrometry for the detection of non-polar environmental analytes within gaseous samples Ross McCulloch Arturo Álvaro Carballido Sociedad Europea de Análisis Diferencial de Movilidad SL (SEADM) (European Society of Differential Mobility Analyzers) Marie Curie Industry-Academia Partnerships and Pathways (IAPP)

2 Motivation Motivation and objectives Develop an ion source for the analysis of vapour samples containing non-polar analytes using DMA-MS technologies Objectives 1. Prototype APPI-DMA-MS source design 2. Characterize and identify key applications 3. Refine source design: produce a commercially viable device

3 Key SEADM Technologies Differential Mobility Analyzer (DMA) Integrates with MS to add an ion mobility dimension Intended to reduce need for LC equipment Minimizes sample throughput time Provide high sensitivity, selectivity & reduce background levels Secondary Electrospray Ionization (SESI) Based on a simple nanospray source configuration Intended for the analysis of vapours Demonstrated high sensitivity

4 The principle Differential Mobility Analyzer (DMA) Continuous ion sampling / high duty cycle Ion transmission up to 50% Resolving power as high as 80 Complete mobility scans in less than 1 minute

5 Two modes: Secondary Electrospray Ionization, SESI 1) Nanospray for liquid samples 2) SESI for vapour analysis - Gas-phase analyte ionization process - Electrospray charger ions Sub ppt LODs Reduced matrix impact Low flow configurations for increased sensitivity

6 Vapour Sampling Method Vapour Sampler The Lab The Field

7 SESI-DMA applications Vapour analysis (explosive screening, breath, etc.) e4 5.0e4 4.5e4 4.0e4 PETN Mixture of explosives separated according to mobility. Intensity n,/ cps s 3.5e4 3.0e4 2.5e4 Detection limits in ppq range for vapour analysis. 2.0e4 1.5e4 1.0e4 EDGN RDX NG Cargo container screening / security applications TNT Mobility / V

8 Why APPI? Atmospheric Pressure Photoionization, APPI ESI/SESI suitable for polars, not ideal for non-polars Applied typically to LC-MS methods; good for non-polar analysis Gas-phase chemical ionization method; adapts well to vapour analysis Dopant (D) generally used to enhance analyte (M) ionization efficiency 1) Robb, D. B., Covey, T., & Bruins, A. (2000). Atmospheric pressure photoionization: an ionization method for liquid chromatography-mass spectrometry. Analytical chemistry, 72(15),

9 Atmospheric Pressure Photoionization, APPI Analytes are efficiently ionized within the gas-phase through various pathways: Charge exchange, proton transfer, electron capture, charged adduction, etc. Works effectively in positive and negative ionization modes. Applicable to both polar and non-polar compounds. Broad linear dynamic range. Most universal source for LC-MS Minimal susceptibility to matrix effects. Comprehensive review of APPI-LC-MS fundamentals: 2) Robb, D. B., & Blades, M. W. (2008). State-of-the-art in atmospheric pressure photoionization for LC/MS. Analytica chimica acta, 627(1),

10 APPI-DMA Prototype Version 1.0 Based upon 1 st generation field-free APPI source configuration 3 Shown to provide advanced sensitivity for LC-MS applications 2 configurations: APPI-MS APPI-DMA-MS 3) McCulloch, R. D., Robb, D. B., Blades, M. Design modifications enabling a performance comparison between early and current generation commercially available atmospheric pressure photoionization (APPI) sources, Proceedings of 57th ASMS conference, Philadelphia, PA (2009)

11 DIOXDETECTOR (Fast Atmospheric Dioxin Detection) Project objective: Method for quantification of dioxins and furans. Track PCDDs/PCDFs in air, soil and vegetable matter at surroundings of incineration facility. Samples collected and extracted No direct vapour analysis APCI/ESI/SESI evaluated. Insufficient sensitivity/ineffective APPI developed to tackle problem. Support of this work was provided by the LIFE+ Program

12 Method Development: fullscan Negative mode: Analytes infused, toluene solvent Dioxins and furans - [M-Cl+O] - HxF HxD Hexachlorodibenzodioxin and 2 ng/ml, in 2 µl/min,

13 Suitability for Dioxin/Furan Screening SEADM: APPI-MS (no DMA); AB Sciex 3200 series QTrap Analysis of liquid standards Log scale LODs ranging from pg; - most detected near 1 pg level Method suitable for trace analysis NDAMN 4 - (HR-GC-MS) Complying with regulations (US EPA Method 1613B1 and Regulation (EC) No. 1883/20062). 4)The National Dioxin Air Monitoring Network (NDAMN) Report of the Results of Atmospheric Measurements of Polychlorinated Dibenzo-p-Dioxins (PCDDs), Polychlorinated Dibenzofurans(PCDFs) and Dioxin-Like-Polychlorinated Biphenyls (PCBs) in Rural and Remote areas of the United States from June 1998 through November 2004.

14 The practical application: Dioxins & Furans Site X Samples obtained from various locations Air (~700 m 3 ), soil (~5 g) and biota/plant (~ 20 g) matter collected & extracted Samples delivered to SEADM for analysis Toxic equivalency (TEQ) estimated Project in early stages Blue January, Red February, Green - March

15 Method development: fullscan Positive mode: Analytes infused, toluene solvent Polycyclicaromatic Hydrocarbons (PAHs) M + Ex. BghiP m/z 276 Ex. Benzo(ghi)perylene ng/ml in 2 µl/min

16 Thermal desorption APPI-MS Benzo(a)pyrene, BaP Desorbed at 250oC MRM method; 12 consecutive samples 2 µl of 100 ng/ml 200 pg 1.10e5 1.05e5 1.00e5 9.50e4 9.00e4 8.50e4 8.00e σ area ~ 30% 5.E+05 4.E+05 BaP - 252/250 BaP - 252/248 Intensity, cps 7.50e4 7.00e4 6.50e4 6.00e4 5.50e4 5.00e Counts/s 3.E+05 2.E+05 R² = e4 4.00e4 3.50e4 3.00e4 1.E+05 R² = e4 2.00e4 1.50e4 1.00e Time, min 0.E mass / pg Toluene added to auxiliary gas

17 Adding the DMA Mobility Element Scan time < 1 min 8000 RPM Impacting Mobility and Resolution DMA gas velocity or pump speed RPM Gas selection (N 2, CO 2, Ar, etc.) Additives (Benzene, IPA, toluene, water, etc.) - Infusion of a standard PAH panel ppb in 2 µl/min

18 Separating isomers/congeners remains a technical challenge for the DMA Ex. BaP and BkF indistinguishable to MS; even in MRM mode Blue BaP + BkF Green BaP Red BkF Benzo(a)pyrene Intensity / cps Benzo(k)fluoranthene m/z m/z Mobility / V Continued goal to improve DMA resolution

19 Deconvolution possible: Blue BaP + BkF Red BaP Green BkF

20 PAH panel Desorption APPI-DMA-MS Analytes deposited on a filter cartridge by micro pipette; desorbed at 250 o C Ion Mobility (Z) voltage optimized and fixed for each analyte Method suitable low level PAH detection (Isomers often not separable) Next step: collect real samples demo full TD-APPI-DMA-MS workflow 1 µl standard panel ppb, 6 analytes (100 pg each)

21 Continued Focus Apply complete APPI-DMA-MS workflows: Develop complete PAH vapour sampling method Expand range of applications: PCBs, pesticides, explosives, biologicals Optimize APPI: evaluate alternative geometries & refine the design General goal to improve DMA resolving power and performance

22 Acknowledgements SEADM Marie Curie (IAPP) Dr. Juan Fernandez de la Mora, Yale University LIFE+ Program -Thank you -