A fluorescence digital image-based method using a 3D-printed platform and a UV-LED chamber made of polyacid lactic for quinine quantification in beverages

A fluorescence digital image-based method using carbon quantum dots to evaluate the compliance of a biocidal agent

“…It is known that the pH medium is an important factor in fluorescence emission, as demonstrated taking the quinine molecule as an example in a previous study. 36 Thus, the fluorescence of CQDs was evaluated in a pH range from 2 to 12 for all RGB data, i.e. , red ( R ), green ( G ) and blue ( B ) (Fig.…”

“…A spot test platform was produced on a 3D printer using a PLA biodegradable polymer with 25 cavities with a maximum volume of 300 μL per microwell. 36 The UV chamber and the 3D platform were previously reported by us, 34 however, here, we focus on developing an in situ method based on fluorescence digital imaging to measure the compliance of a biocidal agent in a sanitizing mat using carbon quantum dots.…”

“…As the interior of the mat has capillary filaments, direct measurement of the fluorescence by spraying the CQD solution into the sanitizing solution of the mat is not the most suitable way, since the presence of these filaments makes it difficult to obtain a homogeneous area and a digital image without brightness or shadows. 33,36,45,46 Thus, in order to overcome this drawback, small aliquots of 500 μL were removed from the sanitizing solution using a micropipette, Deltech Control, every 30 min over 300 min (5 h), except for the first measurement made at 5 min. Then these aliquots are properly filtered (0.45 μm PTFE microsyringe filter) to remove solid particles carried by the soles of the researchers' shoes or dust brought by the winds on the mat.…”

“…For each of the red ( R ), blue ( B ) and green ( G ) channels calibration curves were plotted, as well as the calculation of the vector ( v ) was performed which is based on the Euclidean distance using all RGB data as shown in eqn (1). 36,46 where the parameters R , G and B represent the values referring to the red, green and blue channels, respectively and the parameters R 0 , G 0 and B 0 refer to the RGB values of the blank solution.…”

“…33–35 However, as the efficiency of the sanitizing mat is very important to eliminate the reproduction of virus or bacteria, a sensitive, precise, and accurate method is required, and a variant of the DIB method using fluorescence (FDIB method) was employed. 36 Thus, for the first time in the literature an environmentally-friendly analysis based on an FDIB method was developed using CQDs and a smartphone for a fast, in situ and low-cost approach for measuring hypochlorite in a biocidal product.…”