Chocolate is a complex sample with a high content of
organic compounds and its analysis generally involves
digestion procedures that might introduce the risk of
losses and/or contamination. A variety of analytical
strategies have been developed for the direct analysis of
solid samples and slurries over recent decades; these are
summarized in the book by Kurfu¨ rst. Among the
main advantages claimed for solid and slurry-sampling
are: simplification of sample pre-treatment, reduced risk
of sample contamination, minimization of analyte losses
during the pre-treatment operations or because of
incomplete release of the analyte from the solid matrix,
and no hazardous or corrosive reagents required. Several
recent publications have discussed the analysis of
complex organic matrices that are difficult to mineralize
. Slurry-sampling has been used extensively during
recent years for inductively coupled plasma opticalemission
spectrometry (ICP–OES) electrothermal
atomic-absorption spectrometry and
ICP mass spectrometry using chemical vapor generation [20–23] have also been
proposed. Slurry-sampling methods using flame AAS
(FAAS) are described less frequently in the literature
[24–29], at least in part because of the limited sensitivity
of this technique and the risk of clogging the nebulizer
capillary with sample particles.
The purpose of the present paper was to develop a
fast, simple, and inexpensive method for routine determination
of copper in powdered chocolate samples.
Flame AAS has been considered as an appropriate
technique for that purpose, because it is fast and easy to
use, and available in most analytical laboratories. Slurry-
sampling is proposed instead of sample digestion,
because of the time required, cost, and risks involved in
the latter procedure.