Determination of lead in a chloride matrix by atomic absorption spectrometry using electrothermal vaporization and capacitively coupled plasma atomization

A simple and rapid method using graphite furnace vaporization and plasma atomization for the determination of lead in a sodium chloride matrix was developed, Samples were injected into the furnace of a commercial graphite furnace atomic absorption/plasma emission spectrometer, A relatively low vaporization temperature of 750 degrees C was used to vaporize lead chloride preferentially from the bulk sodium chloride matrix, The lead chloride molecules were then atomized by a capacitively coupled plasma. The lead atomic absorption signal is, therefore, separated from the sodium chloride background absorption temporally, Detection limits (3 sigma) in 3% m/v sodium chloride are 4 and 40 pg of lead using peak absorbance and integrated absorbance, respectively, for a 20 pi sample, The direct determination of lead in sea-water, however, suffers from matrix effects due to magnesium sulfate, Addition of oxalic acid as a chemical modifier eliminates the magnesium sulfate interference, Detection limits (3 sigma) in a sea-water matrix are 28 and 2 pg of lead using peak absorbance and integrated absorbance, respectively, The precision of the method is less than or equal to 7% RSD (five replicates of 20 mu l of a 25 ng ml(-1) Pb sample in either a sodium chloride or sea-water matrix).