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oxidant stream. After the sample is in the oxidant stream, it is mixed with fuel gas and ignited to

from the flame.

The burners used for AAS are of two types.
1. The total-consumption burner

2. The premix or laminar-flow burner

1. The total-consumption burner

In the total-consumption burner the oxidant, fuel, and sample pass directly into the flame
as shown in Fig,

An advantage of a total-consumption burner is that the flame gases are not mixed prior
to being burned in the flame, at prevents the possibility of an explosion and makes it possible to

safely use gases that burn at a high velocity, A large amount of sample passes into the flame
during a fixed period with a total consumption burner. That leads to a relatively high

concentration of the sample in the flame.

A disadvantage of a total-consumption burner is the relatively turbulent flame that
results from the erratic cooling which occurs whenever large drop enter the flame, Large drops

which are not completely vaporized in the flame can scatter radiation. The turbulence in the
flame increases the amount of noise reported by the detector and leads to an unstable

instrumental reading. The shape of the flame from the total-consumption burner is not ideal for

AAS because the path length through the cell is too small for high sensitivity, for these reasons
total-consumption burners are rarely used for AAS.

2. The premix or laminar-flow burner
The turbulence that is associated with a total-consumption burner can be significantly

decreased by removing the larger sample drops prior to introducing the sample into the flame.

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