Determination of Lead in Iron Supplements by Electrothermal Atomization Atomic Absorption Spectrometry

Lead was determined in iron supplements by electrothermal atomization atomic absorption spectrometry (ETA AAS). The effect of the iron matrix on the determination of lead was investigated using line source ETA AAS and high resolution continuum source (HR-CS) ETA AAS. Pyrolysis and atomization curves were obtained using palladium and magnesium as the chemical modifier. The optimal conditions were 1100 degrees C and 2000 degrees C for the pyrolysis and atomization temperatures. Lead was determined by external calibration with aqueous standards; a characteristic mass of 21.3 pg, a limit of detection of 0.25, and a limit of quantification of 0.82 mu gL(-1) were obtained. The limits of detection and quantification using a sample mass of 0.5g were 0.012 and 0.041 mu g g(-1). The relative standard deviation was 5.92% for an iron supplement (iron concentration 280mgg(-1)) with a lead concentration of 2.98 mu g g(-1). The method was employed for the determination of lead in twelve iron supplements from Brazil. The lead concentration was between 0.096 to 7.068 mu g g(-1). These samples were also analyzed by inductively coupled plasma mass spectrometry; no statistical differences were observed by these techniques.