Determination of lead by hydride generation atom trapping flame atomic absorption spectrometry

Abstract

An atom trapping approach is described for the determination of lead by hydride generation flame atomic absorption spectrometry. Lead hydride (PbH₄), generated on-line by reacting lead in hydrochloric acid–potassium ferricyanide medium with sodium borohydride (NaBH₄), was trapped on the interior walls of a slotted T-tube under highly oxidizing flame conditions. Atomization was achieved by aspirating 50 µL of methyl isobutyl ketone (MIBK) to the flame. Optimization of the experimental parameters for the generation and collection of lead hydride was described to achieve the highest peak height sensitivity. The detection limits were 0.075, 0.047 and 0.028 µg L⁻¹ for 2.6, 5.2 and 7.8 mL of blank solution (n = 13), respectively. Calibration was linear up to 3.0 µg L⁻¹ for a 30-s trapping period. The relative standard deviation was between 2 and 4%. The method was successfully applied to the determination of Pb in NIST certified reference materials, San Joaquin Soil (SRM 2709) and Apple Leaves (SRM 1515).