Digital Colorimetry of Indicator Test-Systems Using a Smartphone and Chemometric Analysis in Determination of Quinolones in Pharmaceuticals

A combined approach was developed for the identification and determination of quinolone antibiotics in pharmaceuticals using solid-state fluorescence digital colorimetry and chemometric analysis. The eigen fluorescence of quinolones and quinolone-sensitized fluorescence of europium(III) were studied in various matrices. A test system consisting of four indicator zones was proposed. Irradiation by UV light (365 nm) of quinolone solutions applied to the indicator zones of test systems produced blue fluorescence on cellulose paper (CP) and plates for high-performance thin layer chromatography (HPTLC) and pink fluorescence (CP–Eu, HPTLC–Eu). The fluorescence intensity on the surface of the matrices was measured using a smartphone. It was shown that chemometric analysis, which enabled the analysis time to be reduced and research data to be visualized, could be used. The data were processed by principal component analysis (PCA), hierarchical cluster analysis, and the k-means method using XLSTAT software. Quinolone antibiotics in tablet forms were identified and quantified using chemometric analysis. Calibration curves in the PCA and k-means methods had a logarithmic form in the determined concentration range of 0.5–250 μg/mL (R 2 ≥ 0.98). A technique for determination of fluoroquinolones in pharmaceuticals was proposed. The relative standard deviation did not exceed 0.09.