Spectrophotometric and Liquid Chromatographic Methods for Quantification of Antibacterial Fluorescent Dye (Phloxine B) in Dental Disclosing Tablets and Toothpaste Samples

Double beam UV-Vis spectrophotometry and high-performance liquid chromatography (HPLC) techniques have been used to determine the antibacterial fluorescent phloxine B dye in dental preparations. In the visible wavelength range of 400 to 800 nm, the spectrophotometric signal was obtained at λ_max = 539 nm. The HPLC process used C-18 (5 μm) with a UV detector at 254 nm, 1.5 mL/min flow rate, 0.635 min retention time, and water, acetonitrile, and 2-propanol as the mobile phase. Several parameters have been used to analyze the performance of the HPLC and double-beam UV-Vis spectrophotometry apparatuses, including stability, detection and quantification limits, calibration curves, and repeatability. The study focused on the repeatability of spectrophotometric and HPLC procedures for 8 × 10^–6 and 5 × 10^–6 mol/L of phloxine B. The results showed that the standard deviation (STD) for ten spectrophotometric measurements and eight HPLC measurements, respectively, was ± 0.0004 and ± 2.487 with relative standard deviation (RSD%) of 0.048 and 1.05%. Throughout 90 min of the analysis period, the spectrophotometric and HPLC signals for 8 × 10^–6 and 5 × 10^–6 mol/L of phloxine B were shown to be exceptionally stable. The ranges of the calibration curves were 1 × 10^-6–2 × 10^–5 mol/L for the spectrophotometry and 1 × 10^–5–1 × 10^–4 mol/L for HPLC. Within the concentration ranges under consideration, they were assigned linear relations with correlation coefficients (r²) of 0.9995 for spectrophotometric and 0.99 for HPLC measurements. The detection limits for phloxine B were found to be 1.24 × 10^–8 mol/L (0.0103 ppm) and 8.25 × 10^–7 mol/L (0.068 ppm), respectively, using double-beam UV-visible spectrophotometry and HPLC methods. These techniques use recovery rates ranging from 95 to 111% to determine the phloxine B dye that has been spiked in disclosing tablets and toothpaste samples.