The aim of the present work was to develop and optimize two procedures for the determination of Pb content in honeys by
electrothermal atomic absorption spectrometry without any sample pretreatment. Palladium–magnesium nitrate and ammonium
dihydrogenphosphate were used as chemical modifiers.
Honey was diluted in water, and hydrogen peroxide, nitric acid, and Triton
X-100 were added to minimize the matrix effect. RSD (lower than 10%) and the analytical recovery (98–101%) were acceptable for
both methods. Pd–Mg(NO3)2 was the method selected for further direct Pb determinations in honey samples because it presented the
best limit of detection (LOD = 1.6 ng g1).
Moreover, this method allowed Pb determination using a calibration graph, instead of an
addition graph, which is an important advantage. The direct proposed methods have been applied to the determination of Pb content
in representative honey samples from Galicia (NW Spain). The lead concentrations found in the analyzed samples were in the
range 1.71–75.0 ng g1.
Thirty representative honey samples from Galicia
(NW Spain), with guaranteed origin, and processed
using the traditional procedures in the producing region,
were provided by the Galician Association of Beekeepers
(APLA). All the samples examined were honeys of
random (mixed) floral type. Samples were collected in
glass bottles and stored in the dark at 3–4 C prior to
analysis. Three replicates of each sample were measured
in duplicate.
About 500 ll diluted honey (prepared as described in
Section 2.4) was mixed in the autosampler cup with 125
ll of HNO3 (10%), 10 ll Triton X-100 (1%), 150 ll
hydrogen peroxide (33 % w/v) and made up to 1000 ll
with ultrapure water. 12 ll of this solution was introduced
in the graphite tube together with 9 ll of Pd solution
(2000 lg ml1) and 9 ll of Mg(NO3)2 solution