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Analysis of Drinking Water Using LIBS

Analysis of Drinking Water Using LIBS. December 2012. Applied Research Associates, Inc. Proprietary Information. To Be Covered. LIBS Overview Advantages Methods of Analysis Direct Analysis Pre-concentration Prior to LIBS Analysis PMACS 1000 (for pre-concentration) Summary.

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Analysis of Drinking Water Using LIBS

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  1. Analysis of Drinking Water Using LIBS December 2012 Applied Research Associates, Inc. Proprietary Information

  2. To Be Covered • LIBS Overview • Advantages • Methods of Analysis • Direct Analysis • Pre-concentration Prior to LIBS Analysis • PMACS 1000 (for pre-concentration) • Summary

  3. How does LIBS work? plasma on sample laser • The Laser Plasma • Hotter than the sun’s surface • Plasma lasts ~20 µs receiver 3-5 mm Laser spark on soil • LIBS is a form of atomic emission spectroscopy • Laser pulse creates a spark on the sample material • Light emissions are collected and input into a spectrometer • Processor is used to compare the emissions with our database • Analysis results listed in seconds to minutes depending on sample complexity

  4. LIBS Instrument Configurations are Application Specific General LIBS Set-up SPECTROGRAPH LIBS spectrum analyzed to ID pathogens DETECTOR LASER MIRROR FIBER OPTIC COMPUTER LENS Table top ARA built food prototype: distinguishes E. Coli from Salmonella SAMPLE • LIBS Instruments • Customized for the application • Lab and production line deployment • Size, cost, complexity determined by • the application

  5. Advantages of LIBS for Water Analysis • Rapid analysis for targeted species (<5 min for comprehensive analysis). • Simultaneous detection of all targeted species (eliminates separate tests for individual targets) • No chemical agents or consumables required in contrast to current reagent based methods. • Field deployable LIBS instrument through the use of compact and rugged components available commercially-off-the-shelf. • Automated analysis of all targets through instrument control and analysis software.

  6. Methods of Analysis • Without Pre-concentration of sample using LIBS • Useful when contaminant concentrations are high enough (103 – 109 cells/mL) • Samples could be dried on slides or a direct sampling method could be developed. • Pre-concentration of samples prior to LIBS testing • Useful when contaminant concentration are very low With Pre-concentration Without Pre-concentration

  7. Direct Analysis • Pathogens and other contaminants can be detected in a variety of water matrices by creating chemometric differentiation models for analysis of LIBS spectra and deploying models in an analysis algorithm specifically designed for the detection application. • Recent study of LIBS detection capability in tap water indicates detection is possible in many types of water for concentrations ranging ≥ 103 cells/mL

  8. Tap Water Flow Example of Analysis Algorithm for E. coli, Salmonella, and E. faecalis in Tap water Blank slide or Other? Tap water or Other? E. coli or Other? Salmonella or E. faecalis? E. coli Salmonella Tap water Blank Slide E. faecalis

  9. Differentiation of uncontaminated Tap Water

  10. Differentiation of E. coli in Tap Water

  11. Differentiation of Salmonella from E. faecalis in Tap Water

  12. Pre-concentration prior to LIBS Analysis of Sample • Collect and pre-concentrate particles and organisms in 200 mL volume of aqueous suspension using the PMACS 1000 IntelliSense DesignTM flow system • Collect particles and organisms in the aqueous suspension on a filter substrate • Collect metal ions from the aqueous suspension on ion exchange membrane filters (e.g. 3M Empore® Extraction Disks; 3M Corp. St. Paul, MN). • Interrogate particles, organisms, and metals ions collected on filters using laser spark. R.C. Chinni, D.A. Cremers, and R.A. Multari, “Analysis of material collected on swipes using Laser-Induced Breakdown Spectroscopy (LIBS),” Applied Optics, Vol. 49, Issue 13, pp. C143-C152 (2010). Spark scanned along surface

  13. PMACS 1000 The device is shown in use at the Dunedin, FL water utility for groundwater collection of indicator organisms. Could be used for pre-concentration if necessary. The unit as currently configured has dimensions 36x12x12 inches and a flow rate of 4 L/min. A typical concentration factor is x1000. • Kearns, E.A., S. Magana, and D.V. Lim. 2008. “Automated concentration and recovery of microorganisms from drinking water using dead-end ultrafiltration,” J. Appl. Microbiol. 105:432-442. • Leskinen, S.D. and D.V. Lim. 2008. “Rapid ultrafiltration concentration and biosensor detection of enterococci from large volumes of Florida recreational water,” Appl. Environ. Microbiol. 74:4792-4798.

  14. Collection using the PMACS 1000 (2) Backflush to collect targeted materials on filters (1) Filtration of several liters of drinking water supply (4 L/min. flow rate) Diagram showing flow from a water supply through the PMACS unit to concentrate particles and organisms (metal ions collected on filter ). Diagram showing flow during the Backflush to collect particles and organisms on a filter ( ).

  15. Differentiation of E. coli post pre-concentration

  16. Summary • ARA has demonstrated the ability to differentiate contaminates in water matrices using LIBS • Multiple studies using samples provided by the University of South Florida • Basic Detection Blind Study (100%) • Detection Limit Study (direct detection limit ~103 cells/mL) • Study of LIBS post pre-concentration of sample (10 cells/mL demonstrated) • LIBS for water analysis could be used in real time to • Differentiate “good” from bad water • Monitor for specific contaminations in water • Flag changes in water composition • Advantages of using LIBS: • Fast • Simultaneous analysis of multiple parameters is easily possible • Results can be obtained on-site, in real time

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