The proposed methodology for mercury determination
in fish and shrimp samples using CSA and microwave
digestion shows many advantages. The utilization of
diluted nitric acid at the first step and the addition of
hydrogen peroxide at the second step (when part of the
nitric acid was consumed oxidizing the organic material
of samples) is more favorable than the utilization of nitric
acid plus hydrochloric acid, once this mixture generates
nitrosyl chloride which attacks the gold electrodes and
slightly attacks the microwave-oven Teflon vessels or even
when nitric acid plus perchloric acid are utilized, because
the digestion is not fully completed in this last case (Ahmed
et al., 1981). Despite the digestion process involving a five
step microwave program, the process is completed in less
than one hour. Moreover, the digestion process evolved
the utilization of diluted nitric acid which produces a less
acidic final solution which is an important advantage even
for spectrometric detection.