Design, fabrication and evaluation of a sensor for the determination of lithium in blood

Identifier:  TFG:1620

Handle: https://hdl.handle.net/20.500.11797/TFG1620

Authors:  De La Torre Montaña, Ainhoa

Abstract:
Currently patients treated with lithium salts must deal with the problem of an ineffective treatment due to the narrow therapeutic range of this substance (0.7-1.5mm). Lithium salts, mainly lithium carbonate, are widely used in the treatment of psychological disorders such as bipolarity due to being mood stabilizers. The monitoring of the concentration of lithium in blood is carried out with complex and not very accessible instrumentation. The scientific advances in miniaturization allow to obtain a device that allows the analysis of lithium in blood with high precision, affordable and of small size. In this work, a potentiometric analytical device based on the technique of flow injection analysis (FIA) is designed, manufactured and evaluated. The technology of the cyclic olefin copolymer (COC) is used and a specific ion electrode (ESI) is incorporated for lithium. Various conditioning solutions are tested to achieve the right working conditions. Of the four solutions used (MiliQ water, sodium chloride, magnesium chloride and sodium hydrogen carbonate), hydrogen carbonate makes it possible to reach a compromise between all the parameters evaluated. In addition, combined with a flow rate of 1,91ml/min and an injection volume of 225μl, linearity is achieved in the therapeutic range. This optimizes the analysis time, the consumption of reagents and sample and the quality of the results obtained. The problem of the sodium interference can be solved with the calculation of the selectivity coefficient and the equation to measure lithium with the correction of sodium interference. This device presents the characteristics to accurately determine the concentration of lithium in blood, since the study with synthetic and real samples does not show significant differences between the value obtained during the analysis and the present in the sample.