The urinary levels of catecholamines [adrenaline (AD), noradrenaline (NA), and dopamine (DA)] and their metabolites [L-3,4-dihydroxyphenylalanine (L-DOPA), and 3,4-dihydroxyphenylacetic acid (DOPAC)], as indicators of physiological stress, were assessed in 40 patients with Down syndrome (DS).The analysis was performed by an optical fiber (OF) bioanalyzer; which was constituted by two main components: a miniaturized chromatographic system and a detection system based on an OF coated with an enzymatic matrix. In this study some working conditions such as, number of fibers in the miniaturized chromatographic column, number of dips for sensitive coating deposition, temperature and time of cure of the sensitive matrix, were optimized in order to achieve higher analytical performance. After tested for calibration the bioanalyzer was applied to urine samples analysis of catecholamines and their metabolites, comparing the results with those obtained by both, a classical analytical method, namely high performance liquid chromatography coupled to an electrochemical detector (HPLC-ED), and an OF biosensor based on a sensitive cladding of laccase (LacOF biosensor). The results of catecholamines in patients with DS revealed that 15% and 22.5% of the analyzed subjects showed DA and AD concentrations, respectively, above the pathological levels. In the determinations of NA, the 40 samples showed concentration values below the normal levels, while in the determination of catecholamines metabolites Manuscript 5% of the urine samples showed values above 118 and 1681 g L for L-DOPA and DOPAC, respectively.

A chemical vapour sensor working with a monochromatic light source and based on optical fibre coated with a thin siloxane polymer film has been developed for in situ monitoring of volatile organic compounds, such as ethylbenzene, xylene (o-xylene), heptane, octane, chloroform, carbon tetrachloride, ethanol and butanol in indoor atmosphere and confined areas of industrial environments. The sensor consists on a monomode optical fibre with an end surface coated with a thin polymeric film by dip-coating technique. The light source utilized was a stabilized laser diode at 1550 nm and the light power changes were measured with a photodiode. The sensor was tested for different VOCs and for different individual concentrations regarding stability, sensitivity, repeatability and reversibility of the analytical signal. The response and desorption time have been found to be 30 seconds and good reproducibility and accuracy have been also obtained. Finally, the analytical performance of the developed sensor was also evaluated and found adequate for actual monitoring on indoor atmospheres.