The present study reports a novel sorption-spectrophotometric method for the selective detection of Cd(II) ions in wastewater using the sodium 5-nitro-2-(3-(4-((4-sulfonatophenyl)diazenyl)phenyl)triaz-1-en-1-yl)benzenesulfonate (SNPTSB) immobilized on silk fibroin as a biodegradable and eco-friendly sorbent. The method relies on the formation of a Cd(II) - SNPTSB complex, confirmed by UV-Vis spectroscopy, Raman analysis, conductometry, and SEM-EDS techniques. In solution, a bathochromic shift in the absorption spectrum from 415 nm (free reagent) to 490 nm (complex) was observed, indicating complex formation. In the solid phase, a more pronounced shift from 420 nm to 510 nm (Delta lambda = 90 nm) suggested stronger interactions, likely due to matrix effects. Raman spectroscopy further confirmed metal - ligand coordination, as evidenced by characteristic shifts in the N=N and N-O vibrational modes. Conductometric measurements supported complex formation via a drop in conductivity from 65.8 mu S/cm (Cd2+) and 24.4 mu S/cm (reagent) to 15.2 mu S/cm (complex). The method exhibited excellent linearity (R-2 = 0.9951) within the range of 0.16-2.08 & micro;g/mL, with a molar absorptivity of 2.2 & times; 10(4) L & centerdot;mol(- 1)& centerdot;cm(- 1) and Sandell sensitivity of 0.00122 & micro;g/cm(2). EDS analysis confirmed 5.85% Cd content in the complexed fibre. The method demonstrated high selectivity, with minimal interference from Cu2 +, Fe3 +, Zn2 +, and others (S-r < 0.018). Recovery from complex model mixtures and real industrial wastewater (S-r < 0.052) validated the method's practical applicability. Comparative analysis with inversion voltammetry showed no significant difference (t(obs) = 1.62 < t(tab) = 3.17; F-obs = 1.58 < F-tab = 4.46), confirming the method's reliability and competitive performance.
This study selected three typical mountain pig farms in Bozhou District, Zunyi City, Guizhou Province. The residual concentrations of 44 antibiotics (including SAs, FQs, TCs, and MLs) in the surrounding soil and crops were measured using high-performance liquid chromatography-tandem mass spectrometry. Ecological and health risk assessment were carried out using the risk quotient (RQ) method and the acceptable daily intake hazard quotient (ADI-HQ) method. The results showed that a total of 15 antibiotics were detected in the soil, and the total residual concentrations (mu g/kg) ranked as follows: TCs (3183.72) >FQs (970.61) >MLs (365.34) >SAs (65.28). A total of 18 antibiotics were detected in crops, with total residual concentrations (mu g/kg) in the order of FQs (345.88) >SAs (133.96) >TCs (55.84) >MLs (1.83). Antibiotics in the soil exhibited a significant 'distance decay' trend, with the highest pollution levels and ecological risks observed in the near area (0-50 m). TCs dominated the soil but were rarely detected in crops, whereas SAs had the lowest residues in soil but were significantly enriched in crops such as chilli pepper (overall enrichment coefficient: 1.91). The ecological risk assessment results showed that soil antibiotics generally posed a high risk (total RQ range: 41.54-1276.86), with the risk ranking as TCs > SAs > FQs >MLs. The health risk assessment indicated that only Orbifloxacin was classified as moderate risk, while the overall acute health risk from ingesting other antibiotics through crops was relatively low. This study demonstrates that tetracycline antibiotics are the main pollutants in the soil around pig farms in karst mountainous areas and pose significant ecological risks. Although the health risks of antibiotics in crops are generally low, it is necessary to strengthen the control of antibiotic pollution in the soil surrounding farms and to enhance the supervision of veterinary drug use.
Fluoroquinolone (FQs) antibiotics are frequently detected as emergent contaminants in aquatic environments, necessitating sensitive and reliable analytical methods for their determination. In this study, an integrated in silico and in vivo strategy was developed for the trace-level detection of ciprofloxacin (CIP), norfloxacin (NOR), and ofloxacin (OFL) in diverse water matrices. Separation and quantification were achieved using reversed-phase high-performance liquid chromatography coupled with fluorescence detection (RP-HPLC-FLD). A linear mathematical model was employed to optimise chromatographic parameters, including mobile phase composition, pH, and flow rate, reducing reliance on conventional trial-and-error approaches without compromising chromatographic performance. The optimised excitation-emission wavelength pair (lambda ex = 290 nm; lambda em = 460 nm) was used for all analytes, improving instrumental stability and analytical throughput. Under gradient elution with acetonitrile and methanol at a flow rate of 1 mL min-1, CIP, NOR, and OFL were resolved at 16.68, 15.27, and 14.51 min, respectively, demonstrating high selectivity and sensitivity. Sample preparation employed a magnesium sulphate-driven dual salting-out and drying (MgSO4-D2 S) strategy, providing efficient extraction. The method showed excellent linearity (R2 = 0.99) over 250-5 ng L-1, with recoveries above 90% and precision (RSD) of 0.59-3.87%. Limits of detection were 1.88, 0.79, and 1.57 ng L-1 for CIP, NOR, and OFL, while limits of quantification were 5.70, 2.39, and 4.77 ng L-1, respectively. The method was successfully applied to river, pond, wastewater, tap water, seawater, and microcosm samples, enabling reliable trace-level monitoring of FQs residues in aquatic environmental samples.
The antibiotics can enter the environment through patients' urine samples due to improper metabolism and the disposal of untreated pharmaceutical industrial waste, which can contaminate environmental samples and harm living creatures. Therefore, an economical and easy-to-use method need to be developed for their detection. Carbon dot-based optical methods are advantageous for sensing ultra-low concentrations of various antibiotics. Herein, we report microwave-assisted aqueous synthesis of Nitrogen-doped carbon quantum dots (NCQD) from tartaric acid and 3,3-diaminobenzidine as carbon and nitrogen sources, respectively, for the differential detection of antibiotic ciprofloxacin via fluorescence colour change from green to blue in pharmaceutical formulation, tap water, and milk samples. The as-synthesised NCQD was characterised using FT-IR, Raman spectroscopy, HRTEM, DLS, XRD, and EDX. Methodological investigation disclosed the distinctive properties of NCQD, including excitation-dependent emission, multi-colour fluorescence response in various solvents, and photostability. Moreover, NCQD also exhibits strong radical-scavenging activity, determined by the DPPH assay, and can be used as green and blue fluorescent ink. Aqueous solution of NCQD exhibits a selective and sensitive fluorescence response towards ciprofloxacin antibiotic in the presence of other different classes of antibiotics in an ultra-low concentration, with a detection limit of 14 nM.
