Brooke Dilmetz Quantitation of PFAS using MALDI-TOF MS
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
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
Measuring PFAS: LCMS Liquid chromatography coupled tandem mass spectrometry Advantages Sensitive/Selective Low detection (LOD 0.03 3.0 ng/l 1,2 ) Disadvantages Cost ($200.00-400.00/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, 2017 4. Cao et al. (2011). Talanta 5. Food standards Australia, 2017 University of Adelaide 4
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
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
PFAS analysis by MALDI-TOF MS University of Adelaide 7
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
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
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
Matrices for PFAS Detection Cao et al. (2011) Paper University of Adelaide 11
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
Quantitation of PFAS by MALDI-TOF MS Average Intensity Ratio Average Intensity Ratio PFOS -Matrix: CHCA 60 40 20 0 y = 5.1488x 0.4286 R² = 0.9998 0 2 4 6 8 10 12 Concentration PFOS (ng/ul) PFOA -Matrix: Novel proton sponge 30 25 20 15 10 5 0 y = 2.3366x 0.4994 R² = 0.988 0 2 4 6 8 10 Concentration of PFOA (ng/µl) PFHxS -Matrix: Novel proton sponge Average Intensity Ratio 10 8 6 4 2 0 y = 0.7298x 0.0295 R² = 0.9997 0 2 4 6 8 10 Concentration PFHxS (ng/µl) Above detection limits of drinking water All 3 compounds show linearity (0.1-10ng/µL) MC
Slide 13 MC2 You need to have the ccalculated concentration here Mark Condina, 7/09/2017
Workflow for extraction of samples University of Adelaide 14
SPE of contaminated water sample 250000 Average Intensity 200000 150000 100000 50000 y = 16357x + 9423.6 R² = 0.9862 SPE Contaminated Water Concentration (µg/l) PFOS Evaluation LC-MS Contaminated Water Concentration (µg/l) % Difference 0 0 2 4 6 8 10 12 Concentration of PFOS (ng/ul) 1278.69 1170 8.5 PFOS Calibration Contaminated Water (After SPE) 10 replicates per concentration No heavy labelled standard University of Adelaide 15
Matrix free: NALDI application Nanostructured laser desorption ionisation Disposable target Low mass organic molecules (e.g. 100-2000 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
Quantitation of PFOS by NALDI-TOF 18.00 16.00 Average Intensity Ratio 14.00 12.00 10.00 8.00 6.00 4.00 y = 1.3584x + 0.0997 R² = 0.9912 MC 2.00 0.00 0 2 4 6 8 10 12 Concentration of PFOS (ng/µl) Able to achieve linearity for same concentration range as with matrix Matrix: NALDI target
Slide 17 MC2 You need to have the ccalculated concentration here Mark Condina, 7/09/2017
PFC evaluation by NALDI-TOF MS: screening PFOS Threshold limit: 0.07µg/L 2500 498.915 2000 Intens. [a.u.] 1500 1000 Matrix free allows lower levels of detection for PFOS -Will be used to determine LOQ 500 0 498.5 498.6 498.7 498.8 498.9 499.0 499.1 499.2 m/z University of Adelaide 18
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
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
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: brooke.dilmetz@adelaide.edu.au