Elmer-Rico Mojica

Tetracyclines (TCs) are among the most widely used antibiotics for disease control and livestock feed due to their broad-spectrum therapeutic properties. However, their extensive use, particularly oxytetracycline (OTC) and doxycycline (DC), has led to their widespread presence in water and soil environments, raising ecological and public health concerns. The electron-rich functional groups of TCs, including ketone, carboxyl, amino, and hydroxyl moieties, enable strong complexation with metal oxides, making nanoceramic materials promising adsorbents for their removal. In this study, the adsorption behavior of OTC and DC onto commercial nanoceramics (SiO₂, Al₂O₃, TiO₂, and ZnO) was investigated using UV-Vis absorption, fluorescence spectroscopy, and high-performance liquid chromatography (HPLC). Spectroscopic analyses revealed significant reductions in absorbance and fluorescence intensity upon nanoceramic addition, indicating strong antibiotic adsorption and fluorescence quenching, particularly for ZnO and Al₂O₃. TiO₂ also demonstrated moderate adsorption capacity, while SiO₂ exhibited a distinct behavior, enhancing fluorescence intensity and increasing HPLC peak areas, suggesting weaker adsorption interactions possibly influenced by solvation effects or surface passivation. HPLC results confirmed that DC exhibited a higher adsorption rate than OTC, with TiO₂ and Al₂O₃ achieving over 80 % removal efficiency. The unique behavior of SiO₂ suggests that it does not strongly adsorb tetracyclines but may influence their solubility or molecular stability. These findings provide mechanistic insights into tetracycline-nanoceramic interactions and underscore the importance of material-specific adsorption behaviors for wastewater treatment applications. HIGHLIGHTSThis study uses multiple instruments, including UV-Vis and fluorescence spectrophotometers, as well as high-performance liquid chromatography, to assess the effect of incorporating commercial nanoceramics into tetracycline analogs. GRAPHICAL ABSTRACT

Eucalyptus essential oil was used as a modifier for the carbon paste electrode in the analysis of Pb2+ ions in aqueous samples. To give an optimum current peak for Pb2+ solution, 0.1 M HCl as supporting electrolyte and 10% (w/w) of the modifier were used in the study. Accumulation time of 2 min with pH 6 and deposition time and potential of 150 s and –1500 mV, respectively, gave the optimum conditions for the analysis of Pb2+. Furthermore, results showed that the removal of Pb2+ ions for the regeneration of the electrode can be achieved using multiple stripping of the used electrode. A calibration curve on the analyte concentration of up to 20 ppm was established for lead concentration giving a linearity coefficient of 0.9945. The limit of detection and limit of quantization were also investigated and were found to be 0.87 and 2.90 μA ppm–1, respectively. In the actual laboratory sample, the atomic absorption method gave a Pb2+ concentration of 52.38 ± 0.44 ppm, whereas the voltammetric method gave a Pb2+ concentration of 13.85 ± 5.14 ppm. The results of the study have established and ascertained the ability of the eucalyptus’ essential oil to detect Pb2+; however, it was not highly selective toward Pb2+.

Herbal teas are widely consumed for their health benefits. In this study, the phenolic content and antioxidant capacity of six commercially available banaba (Lagerstroemia speciosa) and sambong (Blumea balsamifera) herbal teas were analyzed. The antioxidant activity was measured using DPPH and ABTS assays, with L. speciosa teas exhibiting higher activity than B. balsamifera teas. The phenolic content was determined using the Folin-Ciocalteu method and showed a direct correlation with antioxidant activity. The market prices based on unit phenolic content and antioxidant activity varied widely with different brands sold online indicating the need for better quality control of the teas analyzed. Bangladesh J. Sci. Ind. Res. 58(4), 265-270, 2023