It was developed an amperometric biosensor to determine tungsten in water, based on the inhibition of
laccase enzyme, by tungsten ions using pyrocathecol as a substrate. The enzyme was immobilized with a proper
mixture containing, bovine serum albumin, and glutaraldehyde, for a cross-linking process over screen-printed
carbon electrodes, previously modified with tetrathiafulvalen and gold nanoparticles. Optimized experimental
conditions are: pyrocatechol in cell 0.040 mM in a phosphate buffer pH 6.5 and applied potential +350 mV. The
repeatability and reproducibility, in terms of relative standard deviation values, of de developed biosensor were
3.3 % (n=3), and 2.2 % (n = 5) respectively, and detection limit was 1.8 × 10-7 mol L-1. Additionally it was
determined the kinetics of the systems by means of Michaelis-Menten Km apparent constants, calculated using
Lineweaver-Burk plots, with and without tungsten. Kinetic study resembles to be competitive inhibition. A
recovery study was performed with spiked blanks with a tungsten certified reference standard, traceable to NIST,
giving as a result 102.3 ± 6.7 %; tap water samples analyzed presented a mean concentration of 1.75 µM, and
recovery of the tungsten certified reference standard on the tap water samples gave 98.8 ± 3.1 %.Universidad de Costa Rica/[804-B5-164]/UCR/Costa RicaUCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Básicas::Centro de Investigación en Electroquímica y Energía Química (CELEQ
