CONICET | Buscador de Institutos y Recursos Humanos

Zinc is a metal with great nutritional importance, necessary in cellular replication and immune response development, with catalytic and regulatory actions on more than 300 enzymes. Growth retardation, altered immune response, premature birth, weight loss, and anorexia are some of the consequences of zinc deficiency. On the other hand, a diet with excess zinc can cause disturbances in energy metabolism or an increase in oxidative stress. The determination of zinc is one of the most difficult and complex analytical tasks, especially at trace levels at complex matrices. Different analytical techniques have been applied to the determination of low concentrations of zinc, such as atomic absorption spectrometry with flame (FAAS) and electrothermal atomization (ETAAS), inductively coupled plasma optical emission spectrometry (ICP-OES), and spectrofluorimetry. The aim of present work was to propose an alternative method for zinc pre-concentration/separation and determination zinc samples, using instruments accessible in quality control laboratories. The metal was complexed with o-phenanthroline and eosin at pH 7.5 in Tris; a piece of filter paper was used as a solid support and solid fluorescent emission measured using a conventional quartz cuvette. Under optimal conditions, the limits of detection and quantification were 0.36 x 10-3 and 1.29 x 10-3 µg L−1, respectively, and the linear range from 1.29 x 10-3 to 4.50 µg L−1. This method showed good sensitivity and selectivity, and it was applied to the determination of zinc in dietary supplements. The use of common filter papers makes it a simpler and more rapid alternative to conventional methods, with sensitivity and accuracy similar to atomic spectroscopies using a typical laboratory instrument. Additionally, its simple operation makes it suitable for routine analysis in the laboratories of toxicology and environmental monitoring.

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