Water for ICP-OES

Impact of Water

• Avoid interferences with the metals being analyzed,
• Enable the instrument to run in optimum conditions, i.e. reduce contamination of the ICP-OES.

• Low ionic content, in order to avoid interference with the analytes. A 18.2 MΩ•cm resistivity ensures that no ions will be present in the water at a level that would interfere with the analyses. High resistivity can be achieved via several technologies, including combination of reverse osmosis, electrodeionization and mixed bed ion exchange resins.
   
• Low particle content to avoid spoiling the nebulizer. The particles include hard particles, as well as colloids. Use of a 0.22 µm filter at the final stage of the purification process ensures that no significant particle count will be present in the water.
   
• Low bacterial count, since bacteria behave as particles, and therefore could spoil the nebulizer as well. Use of a 0.22 µm filter at the final stage of the purification process ensures that bacteria levels below 1 cfu/mL.
   
• Moderate to low organic content. Some large organic molecules such as lignin, as well as humic and fulvic acids resulting from natural matter degradation could stick on the nebulizer surface during the atomization step. Those large organic molecules are efficiently removed by combination of reverse osmosis and activated carbon. Other types of organics may also be removed using UV photooxidation process. 

Example of data obtained on an Iris Intrepid (Thermo) ICP-OES

LOQ: Limit of quantitation

More Information

• Inductively Coupled Plasma: http://www.cee.vt.edu/ewr/environmental/teach/smprimer/icp/icp.html#Combining ICP with Atomic Emission Spectroscopy 

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