2. Experimental
2.1. Recommended procedure for determination of cadmium and
lead in fish samples by Differential Pulse Anodic Stripping
Voltammetry DPASV
Many studies have already been published on the preparation
of samples for wet chemical analysis. Two main techniques
have been used: alkali fusion and acidic decomposition or
extraction. Alkali fusion induces high blank levels and high
detection limits. Due to the small amounts of particulate matter,
acidic methods are more suitable. There are many ways to
proceed with acids. In addition, various parameters, such as
the method of heating, working pressure, and acids, has a role
to play in the digestion efficiency. The use of low quantities of
acid allows small volumes of final solution to be handled and
the detection limits to be improved. The principal acids used
for particle digestion are HNO3, HCl, HClO4, HF, and
H2SO4 (Hseu et al., 2002). However, the use of HF leads to
long, dangerous, and cumbersome schemes and it is not recommended
for routine analysis. Thus, in environmental analytical
chemistry, acid leaching has become a common procedure as
an alternative to total digestion. Five grams of muscles of each
sample (different weight and length) was weighted in Petri
dishes which were put in a closed low temperature (41–
45 C) in an electrical furnace for 24 h and then ground in
an agate mortar. The experimental conditions for the determination
of cadmium and lead by differential pulse anodic stripping
voltammetry are shown in Table 1. The powders of River
Nile samples (S1–S17) and Lake Nasser samples (S1–S12) were
transferred into 100-ml beaker and are mixed with 50 ml