flow to the analyzing device 20 comprises the sum of the gas flow rate of the sampler gas supplied to inlet 5 the carrier gas supplied to inlet 8 plus the flow rate of atomized sample the flow rate of sample vapour is dependent on the volatility of the sample and the temperature of the heating means 4 the sampler gas can be supplied to inlet 5 at a relatively low rate sufficient to transport the atomized sample from the sample chamber 1 however the transport rate can be chosen to provide the desired signal strength and duration the sampler gas is shown controlled by a gas flow controller 11 the balance of the flow is provided by the carrier gas via inlet 8 controlled by gas controller 10 sufficient to provide the desired gas flow rate to the analyzing device by having two separate controllers 10 and 11 the signal strength and duration or proportions of flows can be controlled for optimum performance the flow controller 10 operates to provide two flow rates of the carrier gas one rate when the sample chamber 1 is closed as shown in fig1 and another higher rate when the sample chamber is opened as shown in fig2 so that the gas flow rate to the outlet 9 and the analyzing device 20 is maintained substantially constant the operation of controller 10 can be automated with the use of pressure sensor.