In an inductively coupled plasma [ICP], the flow rate of carrier gas is one of the most significant parameters, while those of coolant and plasma less affect the analytical sensitivity. A sample solution nebulized and transported with the carrier gas passes through the hole, which possesses a lower temperature than the surrounding plasma doughnut1,2. The increase of the nebulizing gas flow rate provides more sample introduction amounts, but the residence time of analyte atoms in the plasma becomes short, which causes the