Aplicaciones de la multiconmutación en química analítica.

Abstract

A high-priority line in Analytical Chemistry is the development of devices that increase the automatization degree and, therefore, reduce the human participation in the analysis procedures. The demand of information makes necessary the development of simple, cheap, fast and clean methodologies. The main contribution of this Thesis has been the study, development and comparison of analytical procedures that use the multicommutation in three different areas: (1) Mechanization in AFS, (2) Mechanization in molecular spectrophotometry, (3) Application to portable and economic instruments. In the first block multicommutation allows the mechanization of AFS measurements: Hg, Bi and Te. These are the first works in the literature about multicommutation in AFS. In the second block multicommutation is used as the analytical tool for the mechanization of the spectrophotometric measurements: (i) Liquid-liquid extraction for the determination of anionic surfactants in waters, with a high sampling frequency. (ii) Use of the minipumps as fluid propulsive units to substitute the solenoid valves and the peristaltic pump, and to reduce the price of the system. This strategy has been developed for the phenol and cyclamate determinations in waters and table sweeteners, respectively. The third section is dedicated to the benefits of multicommutation in its application to portable and economic instruments: (i) Luminometer for H2O2 and NH4 + determinations. (ii) LED photometer for the determination of Fe3+, NO2-, phenol and carbaryl. The aforementioned methods have been validated in terms of accuracy, precision, limit of detection by means of recovery studies and comparison with reference methods. In general, it is possible to affirm that: 1. Multicommutation provides a considerable increase in the productivity of the laboratory, decreasing the time of the analyses. 2. Multicommutation reduces the consumption of reactive and samples and the waste volume, increasing the safety and minimizing the costs. 3. Multicommutation provides versatility, flexibility, economy, robustness and miniaturization of the systems. In addition, multicommutation allows its automatization to design portable equipments for analysis in situ. In conclusion, this Thesis has contributed to different and simple applications of the multicommutation in Analytical Chemistry.