Methods that Convert Solid Samples into an Aerosol or Vapour

2 Methods that Convert Solid Samples into an Aerosol or Vapour. These methods include (i) electrothermal vaporization, (ii) arc and spark ablation, and (hi) laser ablation. 

The sample is placed on the surface of the vaporizer in solid or in liquid form. At the vaporization stage a dry, highly dispersed aerosol is produced. The aerosol is subsequently swept into the plasma by the carrier gas (usually argon) and a transient emission signal is obtained. 

In one ETV device the electrothermal vaporization chamber is connected directly to the ICP torch assembly. In this design the distance that the sample must travel from the surface of the vaporizer to the plasma is kept minimal (about 30 cm) and the vaporization chamber is small (about 50 cm ) in order to prevent diffusion of the analyte peak and to minimize loss of the sample to the walls of the delivery system. The sample is inserted into a tantalum boat, mounted on brass supports through which the power is applied. 

Another ETV system is a modified version of an AAS atomization chamber. The sample is placed on a pyrolytically coated graphite microboat supported by a carbon rod and its mounting assembly. The vaporization heating cycle is controlled by a programmable power supply. The vaporizer assembly is connected to the plasma by a PTFE tube (12 cm in length). 

ETV-ICP is an extremely sensitive technique due to highly efficient sample utilization. Detection limits for aqueous solutions are generally 10 to 100 times better than those obtained using solution nebulization. For solid samples, detection limits fall to the nanogram-to-picogram range. The sample size typically used is 0.5 mg. 

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