Nebulizers, Spray Chambers and Torches

Nebulizers

Pneumatic Nebulizers

The term "pneumatic" is defined as 'of or relating to or using air or a similar gas'. The word "nebulizer" is derived from the Latin "nebula" meaning mist and is defined as 'an instrument for converting a liquid into a fine spray'. Therefore, a pneumatic nebulizer is literally an instrument for converting a liquid into a fine spray that uses a gas as the driving force.

Some of the most popular ICP pneumatic nebulizers are:

     •  Concentric glass
     •  Concentric PFA
     •  Fixed Cross-Flow
     •  Lichte (modified)
     •  Micro-concentric glass
     •  Adjustable Cross-Flow
     •  High-Pressure Fixed Cross-Flow (MAK)
     •  Babington V-Groove (high solids)
     •  GMK Babington (high solids)
     •  Hildebrand dual grid (high solids)
     •  Ebdon slurry (high solids)
     •  Cone Spray (high solids)

The concentric and fixed cross-flow are still the most common designs. The construction of both types is described in the following article by ICP expert Robert Thomas (see Figures 4 & 5):

• A Beginner's Guide to ICP-MS - Part II: The Sample-Introduction System

ICP manufacturers will give you an option as to the type of nebulizer to use depending upon your analytical requirements and the instrumental design.

Sound can be used instead of a gas as the energy source for converting a liquid to a mist. These nebulizers use an ultrasonic generator at a frequency of between 200 kHz and 10 MHz to drive a piezoelectric crystal. A pressure is produced that breaks the surface of the liquid - air interface. Ultrasonic nebulizers are more expensive and difficult to use but they will improve (lower) detection limits by about a factor of 10. For more information on ultrasonic nebulizers, visit the following link:

• CETAC U-5000+ Ultrasonic Nebulizer with Axial ICP-OES

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