Effect of Cobalt as a Chemical Modifier for the Determination of Lead by Electrothermal Atomic Absorption Spectrometry Using a Tungsten Furnace

Abstract

The effectiveness of cobalt as a chemical modifier was investigated for the determination of lead by electrothermal atomic absorption spectrometry using a tungsten furnace. A 10 µl aliquot of the 0.1% m/v cobalt modifier (CoCl ₂ in 1 M HCl) was dropped onto a tungsten metal board and pre-heating was carried out at 1200 °C. After the addition of a solution containing lead, followed by charring at a temperature of 1000 °C, the absorbance of lead was measured at an atomization temperature of 2400 °C. The loss of lead by volatilization could be suppressed at charring temperatures up to 1250 °C by the addition of the cobalt modifier. The relative standard deviation at the 0.06 mg l ^-1 lead level was less than 3% ( n =5) and the detection limit (S/N=3) was 0.07 ng.