Abstract
Irradiation with ultraviolet (UV) energy was investigated to assay cadmium, copper, lead, and zinc by anodic stripping voltammetry (ASV) in amino acid parenteral nutrition (PN) solutions. Sample digestion by UV irradiation showed the best performances to liberate the metals from the samples (metal recoveries between 90% and 102%) in comparison with classical oxidative wet digestion methods. The best UV digestion condition was obtained with 1:10 diluted PN samples irradiated during 10 h at 90±3°C with the addition of one aliquot of 50 µL concentrated H2SO4 and repeated additions of 50 µL 30% (v/v) H2O2 at each 60 min irradiation interval. By using the UV digestion procedure cadmium, copper, lead, and zinc were simultaneously assayed in commercial amino acid PN solutions by ASV. The metal concentrations ranged between 1.3 to 4.4 for cadmium, 2.9 to 40.8 for copper, 4.4 to 16.8 for lead, and 1.4 to 208.5 for zinc. The ASV method correlated well with atomic absorption spectrometry measurements to assay the investigated analytes in amino acid PN samples after the UV digestion.
We are grateful to the Brazilian foundations CAPES, CNPq and to Metrohm AG (Herisau), for financial support.