Novel paper-based method for determination of zinc in water samples using solid state fluorescence

MESSINA GERMÁN A.; BIASI, ANTONELLA DE LAS MERCEDES; GOMEZ, NIDIA

Congreso; XXXV Reunión Científica Anual de la Sociedad de Biología de Cuyo; 2017

Zinc is an essential trace element with great nutritional importance; it is indispensable for the normal growth and the reproduction of humans. In addition, it plays a key role in immune function. The determination of zinc in foods and beverages at trace levels is one of the most difficult and complex analytical tasks. The purpose of this work was to propose an alternative method for the quantitative determination of zinc in water using a paper-based pre-concentration/separation method coupled to detection by solid state fluorescence (SSF). Zinc present in water samples and standards was complexed with a mixture of o-phenanthroline 5.0 x 10-7 M and eosin 5 x 10-8 M at pH 7.5 in Tris buffer 5.0 x 10-4 M. Pieces of Blue Ribbon filter paper (1cm) were impregnated through contact with each mixture for 1 min (n = 5). Then, the filter papers were dried at room temperature and finally, they were arranged in a conventional quartz cell adapted for solid support. Then, the samples were determined at λem = 445 nm (emission) and λext = 380 nm (excitation). A calibration curve for different concentrations of Zn(II) from 1.5 x 10-3 to 5.0 µg L-1 was realized by applying the proposed method. The determination of Zn(II)was possible with a limit of detection of 1.5 x 10-3 µg L-1. The non-sophisticated equipment required, the sensitivity, accuracy and the appropriate LOD achieved by our method, represent relevant parameters, particularly when the determination of zinc at trace levels is considered.