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

3. Glass Expansion www.geicp.com 1 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

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

5. Glass Expansion www.geicp.com 1 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

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

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

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

9. Glass Expansion www.geicp.com 1 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

10. Glass Expansion www.geicp.com 1 Theory of Sensitivity Enhancement Todoli and Mermet, JAAS, Aug., 1998, Vol. 13, p.730 “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.”

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

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

13. Glass Expansion www.geicp.com 1 Theory of Intensity Enhancement Smaller 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

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

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

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

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

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

19. Glass Expansion www.geicp.com 1 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.