Sample Introduction Methods:

The sample introduction into the flame is an important step in flame AAS measurements as its precision, accuracy and detection limits depend on how the analyte sample is introduced. The goal of a sample introduction system is to transfer a reproducible and representative portion of a sample into an atomiser. It depends on the physical and chemical state (i.e. solid, liquid or gas) of the analyte and the sample matrix such as soil, plant leaves, blood, water, etc. For solution and gaseous samples, the introduction step is quite simple but for solid, it poses a major problem.

You have learnt that a simple method of sample introduction into the flame is nebulisation. It is a procedure of thermal vaporisation and dissociation of aerosol particles at high temperatures thus producing small particle size with high residence time. Some nebulisation methods are given below.

• Pneumatic nebulisation
• Ultrasonic nebulisation
• Electrothermal vaporisation
• Hydride generation