Brooke Dilmetz. Quantitation of PFAS using MALDI-TOF MS

Transcription

1 Brooke Dilmetz Quantitation of PFAS using MALDI-TOF MS

2 Per and polyfluoroalkyl substances PFOS and PFOA manufactured from early 1950 s present 1 Highly persistent and bioaccumulative PFOS (Perfluorooctanesulfonate) PFOA (Perfluorooctanoate) 1 Oliaei et al. (2013). Environ Sci Pollut Res University of Adelaide 2

3 Per and polyfluoroalkyl substances PFOS and PFOA manufactured from early 1950 s present 1 Germany, Italy and China Highly persistent and bioaccumulative - Evidence that PFAS: Disrupt normal endocrine activity; Reduce immune function; Cause adverse effects on multiple organs, including the liver and pancreas; PFOS (Perfluorooctanesulfonate) Cause developmental problems in rodent offspring exposed in the womb. 2,3 PFOA (Perfluorooctanoate) 2 Lindstrom AB, Strynar MJ, Libelo EL. (2011). Environ Sci Technol 3 White SS, Fenton SE, Hines EP. (2011). J Steroid Biochem University of Adelaide 3

4 Measuring PFAS: LCMS Liquid chromatography coupled tandem mass spectrometry Advantages Sensitive/Selective Low detection (LOD ng/l 1,2 ) Disadvantages Cost ($ /sample 3 ) Time - column conditioning, - carry-over Contamination of fittings and tubing 4 Drinking water quality guideline 5 PFOS 0.07µg/L PFOA 0.56µg/L 1. Zheo et al. (2011). Mircochem. 2. Shimadzu, Application note C81 3. Adelaide Proteomics Centre, Cao et al. (2011). Talanta 5. Food standards Australia, 2017 University of Adelaide 4

5 PFAS analysis by MALDI-TOF MS Typical analytes are macromolecules (proteins, polymers) Limited for the detection of small molecules (M.W. <500 Da) Analyte co-deposited with matrix University of Adelaide 5

6 PFAS analysis by MALDI-TOF MS Advantages High throughput MS analysis: typically 2-10 sec/spot Able to analyse multiple samples: 1536 spot plate format (800µm) No carry-over: Straight-forward target washing Low Cost ($5-10 per sample) Disadvantages: small molecule analysis Quantitation is difficult, due to: o Matrix interference for small molecules o Spot-spot variability University of Adelaide Technical Note # TN-41, Bruker Daltonics GmbH 6

7 PFAS analysis by MALDI-TOF MS University of Adelaide 7

8 Project Aims To create a screening platform for the detection of PFAS by MALDI-TOF MS 1. Determine suitable matrices for PFAS detection 2. Determine LODs/ LOQs for various PFAS 3. Quantify of PFAS spiked into water samples 4. Apply methodology to contaminated water sample University of Adelaide 8

9 MALDI Matrix Properties Strong UV light absorption at the wavelength of the laser (355nm) Typically low molecular weight acid Different matrices for different analyte classes ionisation threshold Name Other Names Applications α-cyano-4-hydroxycinnamic acid CHCA Peptides and proteins 2,5-Dihydroxybenzoic acid 2,5-DHB Peptides, phosphoprotein digests, glycoprotein digests, proteins, glycans 2,5-Dihydroxyacetophenone 2,5-DHAP Proteins Sinnapinic acid SA Proteins, lipids 3-Hydroxypicolinic acid 3-HPA Oligonucleotides University of Adelaide 9

10 Matrices for PFAS Detection TMGN Replicate 1 TMGN Replicate 2 TMGN Replicate 3 TMGN Replicate 4 TMGN Replicate 5 Cao et al. (2011) Paper University of Adelaide 10

11 Matrices for PFAS Detection Cao et al. (2011) Paper University of Adelaide 11

12 Matrices used for detection of PFAS Matrix Advantages Disadvantages CHCA Homogenous crystallisation Interfering matrix ion peaks CHCA for PFOS Novel Proton Sponge Less interfering matrix peaks Heterogeneous crystallisation Novel Matrix for PFOA Novel Matrix for PFHxS TMGN Homogenous crystallisation Interfering matrix ion peaks Matrix-free applications NALDI Monoliths University of Adelaide 12

13 Quantitation of PFAS by MALDI-TOF MS Average Intensity Ratio Average Intensity Ratio PFOS -Matrix: CHCA y = x R² = Concentration PFOS (ng/ul) PFOA -Matrix: Novel proton sponge y = x R² = Concentration of PFOA (ng/µl) PFHxS -Matrix: Novel proton sponge Average Intensity Ratio y = x R² = Concentration PFHxS (ng/µl) Above detection limits of drinking water All 3 compounds show linearity (0.1-10ng/µL) MC

14 Slide 13 MC2 You need to have the ccalculated concentration here Mark Condina, 7/09/2017

15 Workflow for extraction of samples University of Adelaide 14

16 SPE of contaminated water sample Average Intensity y = 16357x R² = SPE Contaminated Water Concentration (µg/l) PFOS Evaluation LC-MS Contaminated Water Concentration (µg/l) % Difference Concentration of PFOS (ng/ul) PFOS Calibration Contaminated Water (After SPE) 10 replicates per concentration No heavy labelled standard University of Adelaide 15

17 Matrix free: NALDI application Nanostructured laser desorption ionisation Disposable target Low mass organic molecules (e.g m.w.) ion target Surface deposited layer of inorganic nanostructures Daniels, H., Dikler, S. Technical Note 22, Bruker Daltonics, and NanoSys Inc. University of Adelaide 16

18 Quantitation of PFOS by NALDI-TOF Average Intensity Ratio y = x R² = MC Concentration of PFOS (ng/µl) Able to achieve linearity for same concentration range as with matrix Matrix: NALDI target

19 Slide 17 MC2 You need to have the ccalculated concentration here Mark Condina, 7/09/2017

20 PFC evaluation by NALDI-TOF MS: screening PFOS Threshold limit: 0.07µg/L Intens. [a.u.] Matrix free allows lower levels of detection for PFOS -Will be used to determine LOQ m/z University of Adelaide 18

21 Conclusions Quantitate using MALDI-TOF MS Possible to achieve quant without labelled standard (higher variance) Able to detect down to required thresholds using matrix free platform MALDI-TOF MS offers high-throughput assessment of samples after SPE enrichment Able to screen 1000 s samples low cost More comprehensive sampling of potentially contaminated areas Able to determine which samples to be analysed by LCMS (if required) University of Adelaide 19

22 Future work Improve LOQ and LOD for MALDI and determine for NALDI Improve MALDI-TOF MS acquisition Lower acquisition time per spot Evaluate alternative enrichment strategies for PFAS Porous monolithic material for enrichment Investigate other matrix-free applications: Porous monolithic surfaces Laser desorption/ionisation (LDI) Poly(butyl methacrylate-co-ethylenedimethacrylate) monolith Poly(styrene-co-divinyl benzene) monolith University of Adelaide 20

23 Acknowledgements Yin Ying Ho Parul Mittal Christopher Cursaro Matthew Briggs Mitchell Ackland Chao Zhang Noor Alia Lokman Carly Gregor Prof. Peter Hoffmann Dr. Mark Condina Dr. Dario Arrua Dr. Lyron Winderbaum Silvana Napoli Dr. Richard Stewart Contact information: