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SPRAY CHAMBER TEMPERATURE: A CRITICAL (YET OFTEN MISSING) PARAMETER IN ICP EXPERIMENTS

SPRAY CHAMBER TEMPERATURE: A CRITICAL (YET OFTEN MISSING) PARAMETER IN ICP EXPERIMENTS. Jerry Dulude, Ron Stux, and Vesna Dolic, Glass Expansion, jdulude@geicp.com . Focus of this study on ICP-OES. Effect of Spray Chamber Temperature on: Analyte sensitivity Detection limits

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SPRAY CHAMBER TEMPERATURE: A CRITICAL (YET OFTEN MISSING) PARAMETER IN ICP EXPERIMENTS

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  1. SPRAY CHAMBER TEMPERATURE: A CRITICAL (YET OFTEN MISSING) PARAMETER IN ICP EXPERIMENTS Jerry Dulude, Ron Stux, and Vesna Dolic, Glass Expansion, jdulude@geicp.com

  2. Focus of this study on ICP-OES • Effect of Spray Chamber Temperature on: • Analyte sensitivity • Detection limits • Matrix interferences • Plasma robustness Glass Expansion www.geicp.com 1

  3. Experimental • PE 2100 Optima DV • Power: 1450 watts • Coolant gas: 15LPM • Aux. gas: 0.2LPM • Neb. Gas: 0.7LPM • SeaSpray concentric glass nebulizer • IsoMist Programmable Temperature spray chamber with Twister Baffled Cyclonic Glass Expansion www.geicp.com 1

  4. IsoMist on Optima 2100DV Glass Expansion www.geicp.com 1

  5. IsoMist Characteristics • Programmable from -10 to 60C in 1 degree increments • Maintains temperature to within 0.1 degree • Built-in Peltier device • Temperature measured near the chamber surface • No external plumbing Glass Expansion www.geicp.com 1

  6. Effect of Temperature on Normalized LOD (20ul/min Uptake) PE Optima 2100DV Glass Expansion www.geicp.com 1

  7. Effect of Temperature on Normalized Intensity (20 uL/min) PE Optima 2100DV Glass Expansion www.geicp.com 1

  8. Transport Efficiency vs. Uptake Rate Glass Expansion www.geicp.com 1

  9. Unexplained Intensity Enhancement • 200% enhancement at 60C • 67% possible from transport efficiency • Where is the missing 133%? • Higher energy plasma • Smaller mean droplet size The Phenomenon Theories Glass Expansion www.geicp.com 1

  10. Theory of Sensitivity Enhancement “When water is the solvent, an increase in the solvent loading under robust conditions leads to an increase in the MgII/MgI ratio. …the generation of hydrogen will increase locally the thermal conductivity of the discharge.” Todoli and Mermet, JAAS, Aug., 1998, Vol. 13, p.730 Glass Expansion www.geicp.com 1

  11. Humidification Test • Measure intensity in “bypass” mode. • Switch to humidification “ON” mode • Re-measure intensity without changing conditions Capricorn™ Argon Humidifier Glass Expansion www.geicp.com 1

  12. Effect of Humidification on Intensity(100ul/min uptake rate) Glass Expansion www.geicp.com 1

  13. Theory of Intensity EnhancementSmaller Mean Droplet Size • Initiate evaporation in the chamber • Smaller particles reach the plasma • More efficient atomization • Higher intensity • Use phase Doppler particle analyzer to measure mean droplet size Glass Expansion www.geicp.com 1

  14. Sensitivity vs. Temperature(1ml/min uptake) Glass Expansion www.geicp.com 1

  15. Intensity and Transport Efficiency vs Temperature Glass Expansion www.geicp.com 1

  16. Temperature vs. Robustness(Mg+/Mg Ratio) 1ml/min uptake 1000ppm Na + K 500ppm Ca Glass Expansion www.geicp.com 1

  17. Temperature vs. Suppression(1ml/min uptake) 1000ppm Na + K 500ppm Ca Glass Expansion www.geicp.com 1

  18. Suppression and Intensity vs. Temperature(average of 18 lines) 1ml/min uptake 1000ppm Na + K 500ppm Ca Glass Expansion www.geicp.com 1

  19. Summary • Spray chamber temperature is a critical parameter in ICP-OES experiments. • Intensity is proportional to temperature. • Suppression is unrelated to temperature. • Plasma robustness increases with temperature. • Constant temperature is important for all analyses. Glass Expansion www.geicp.com 1

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