Determinación de la cantidad de plomo (ii) presente en fresas frescas provenientes de la vereda la unión en el municipio de Sibaté en Cundinamarca – Colombia, por medio de voltametría de onda cuadrada (swv)

Abstract

This project carried out the determination of Pb (II) present in a sample of fresh strawberries from a farm called Finca A, located in the village of La Unión in the municipality of Sibaté in Cundinamarca - Colombia, through the technique square wave voltammetry (SWV). This technique was selected for offering low operating cost, high sensitivity, selectivity and easy adaptation to the work environment. The determination of Pb (II) was decided on the fruit of the strawberry because it is one of the fruits with the highest economic contribution in the country and for having found more than one electroactive species in this fruit according to studies focused on the determination of metals at the National and international. Thus, a strawberry sample was taken and analyzed from the path closest to the reservoir of Muña, characterized by being a body of stagnant water and with a high degree of contamination, making its environment a focus of interest for environmental research. In this way the quantification of Pb (II) was performed after using the acid digestion method, which took the sample to aqueous solution, with a configuration in the electrochemical cell of 3 electrodes, glassy carbon or GC as working electrode, Ag / AgCl as a reference electrode and Pt as a counter electrode, in acetate electrolyte acetate buffer at pH 4.5. Then the parameters of the technique were established as follows: step size 25 mV, frequency 60 Hz and pulse size 80 mV with quiet time of 15s. Finally, the standard addition method was used as one of the best methods for reducing interference, such as the matrix effect, facilitating the determination of 0.3012 ppm of Pb (II) in the strawberry sample, a value that exceeds the permissible limit established by the Colombian regulations that is located in 0.20 ppm of Pb for berries and small fruits. Furthermore, other electroactive species were observed which generated current peaks in different voltages, showing that the square wave voltammetry technique is suitable for the determination of more than one electroactive substance and quantify it separately in foods such as strawberries.