Abstract
The study is devoted to the development of a fluorimetric version of the “fingerprint” method based on conducting indicator reactions in the presence of an object. Observing the reaction over time increases the amount of information received compared to the static version, which allows for improved object recognition, as well as quantitative analysis. As an indicator reaction, it is proposed to use the interaction of a commercial carbocyanine dye with 4-dimethylaminobenzaldehyde, which leads to a decrease in the intensity of fluorescence and a change in light absorption over time. Three fluoroquinolones (moxifloxacin, levofloxacin and ofloxacin) selectively alter the signal at concentrations ≥1 µm; other medicinal substances, including other fluoroquinolones, do not interfere. Ofloxacin was determined in human urine samples at different times after taking the drug. The possibility of using the same indicator reaction for object recognition is shown on the example of samples of apple juices, soil extracts and meat of varying degrees of freshness. Chemometrics methods, including linear discriminant analysis, were used to process the data. 15 apple juices were discriminated with 97% accuracy, 10 apple juices produced in 2022 and 2023 (94%), 10 soil samples (99%), and the possibility of determining the freshness of meat was shown using the example of five samples.