Publications by authors named "Alegre N S Cadeado"

Portable and affordable (spectro)photometers based on digital color sensors are gaining significance in analytical chemistry due to their compact design, cost-effectiveness and integration capabilities. Despite their inherent straight-forward operation, various digital light sensors with distinct performance and optical characteristics are available on the market. For instance, AS7341 and AS7262 are multi-channel color sensors that covers eight and six spectra regions, respectively, while TCS34725 operates using three channels (red, green, and blue).

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This study introduces a novel optical method for formaldehyde determination in milk, based on the hypothesis that simultaneous reflectance and fluorescence measurements can enhance detection sensitivity compared to traditional methods. We aimed to address the challenge of accurately measuring low concentrations of formaldehyde in milk, a crucial issue for food safety. By employing a multi-channel spectrometer sensor and exploiting the reaction of formaldehyde with acetylacetone to form 3,5-diacetyl-1,4-dihydrolutidine (DDL), we measured reflectance of DDL at 415 nm and fluorescence at 515 nm.

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In this work we present a novel and environmentally friendly approach for quantifying glycerol in wine samples using a portable optical device based on the maker concept and do-it-yourself (DIY) principles. This method offers significant advantages, including cost-effectiveness, reduced sample and reagent consumption, and the potential for integrating IoT (Internet of Things) technology. The chemical strategy involves the oxidation of glycerol using periodate, followed by the formation of the 3,5-diacetyl-1,4-dihydrolutidine (DDL) compound through a reaction with acetylacetone.

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