Sociedade Brasileira de Espectrometria de Massas – BrMASS
Environmental ANALYSIS – ENV
Clearance of cadmium in tilapias (O.niloticus) by using the
111
Cd/114Cd isotopic ratio
Thiago A. Dourado2, Tatiana S. Motta1, José R. Ferreira1, Jorge H.
Pedrobom2, Amauri A. Menegário2, Maria F. Giné1.
[email protected]
1
Centro de Energia Nuclear na Agricultura (CENA-USP)
Centro de Estudos Ambientais, UNESP- Univ. Estadual Paulista, Rio Claro,
SP, Brasil.
2
With the aim of tracing the clearance of cadmium in tilapias (O.niloticus), the enriched
isotope
111
Cd (95,5%) - Cambridge Isotope Laboratories – CIL, Inc., was used through
intraperitoneals injections. To reach for these goals, two aquariuns with 40 L capacity,
containing 10 fish each, with an individual average weight of 20g were employed. For
the control treatment it was injected 200 µL of a 0,6% NaCl (w/v) solution only, while
for the cadmium treatment 200 µL of a 15 mg L-1
111
Cd diluted in a 0,6% NaCl (w/v)
solution were used per fish. The clearance of Cd was monitorated every 24 h, during 7
days period for both assays. The
111
Cd/114Cd isotopic ratios were determined by
inductively coupled mass spectrometry (ICP-MS) in water samples which were
previously digested using HNO3:H2O2 (3:1) mixture. As expected, the highest isotopic
ratios, which varied in the range of 0.501 to 0.543, were obtained for the
111
Cd
treatment. In the Control treatment isotopic ratios varied from 0.408 to 0.438, being
close to those values observed for the natural standards used in the analytical
calibration curve. The highest Cd excretion occurs at the third day of the beginning of
the experiment (RI=0,543), followed by a slight decrease in the fourth one
(RI=0,509), being stable from the day after to the end of the assay, with an average
isotopic ratio of 0.507, still far from the observed values of the Control treatment
ratios, denoting the intraperitoneal injection as the source of
111
Cd to the aquatic
system.
Financial support: FAPESP, CNPq
Sociedade Brasileira de Espectrometria de Massas – BrMASS