Fluorescence derivatization enables sensitive delafloxacin measurement in drugs and plasma

Researchers have developed a highly sensitive spectrofluorimetric method for measuring the antibiotic delafloxacin, based on derivatizing the molecule with 9-fluorenyl methyl chloroformate (FMOC-Cl) to unlock a strong fluorescent signal. The derivatization reaction takes place at room temperature in borate buffer at pH 8.0, producing a strongly fluorescent derivative that is suitable for sensitive quantitative analysis. The work, published in BMC Chemistry, was carried out by a team led by Hany A. Batakoushy, with co-authors including Galal Magdy, Anmar Anwar Khan, Rehab H. Elattar and Mai A. El-Didamoony.

The fluorescent derivative emits at wavelengths that allow precise detection: maximum excitation occurs at 264 nm and maximum emission at 314 nm. The team systematically investigated and optimized the experimental parameters that affect both the derivatization reaction and the resulting fluorescence response, tuning the conditions to maximize sensitivity and reproducibility before applying the method to real samples.

Analytical performance was a central focus of the study. The method showed good linearity over a concentration range of 5.0 to 100.0 ng mL⁻¹, with a correlation coefficient of 0.9994. The limits of detection and quantification were 1.25 and 3.81 ng mL⁻¹, respectively. Accuracy and precision were described as satisfactory, with a mean recovery of 101.43% ± 0.64. These figures indicate that the assay can reliably quantify very low concentrations of the drug, a level of sensitivity that is relevant for bioanalytical work where sample volumes and drug concentrations may be limited.

The applicability of the method was confirmed through the determination of delafloxacin in pharmaceutical preparations and in spiked human plasma samples. When the results were statistically compared with a reported reference method, no significant difference was found between the two sets of measurements, supporting the validity of the new approach. The use of spiked plasma means the method was validated on prepared samples rather than demonstrated in a clinical study, and the authors position the technique for pharmaceutical quality control and bioanalytical investigations rather than direct patient testing.

Beyond raw sensitivity, the researchers also evaluated the environmental profile of the method using two assessment frameworks: the Carbon Footprint Reduction Index (CaFRI) and the White Analytical Chemistry Evaluation (WECA).

By attaching a fluorescent tag through a simple room-temperature reaction, the method converts the target into a readily detectable species without requiring complex instrumentation beyond a spectrofluorimeter.

The authors conclude that the proposed fluorescence derivatization method provides a sensitive, precise and accurate approach for determining delafloxacin in pharmaceutical and spiked plasma samples, and that its favorable analytical performance and environmental assessment support its potential application in routine pharmaceutical quality control and bioanalytical investigations. The article was published as open access research on 28 October 2026 and is being shared early as a peer-reviewed, accepted version subject to further edits before the final Version of Record.

Subject of Research: A sensitive spectrofluorimetric method for determining delafloxacin in pharmaceutical preparations and spiked human plasma using FMOC-Cl fluorescence derivatization.

Article Title: Unlocking delafloxacin fluorescence with 9-fluorenyl methyl chloroformate: A sensitive spectrofluorimetric method for pharmaceutical and plasma analysis with greenness and whiteness assessment

Article References: Batakoushy, H. A., Magdy, G., Khan, A. A., Elattar, R. H., & El-Didamoony, M. A. (2026). Unlocking delafloxacin fluorescence with 9-fluorenyl methyl chloroformate: A sensitive spectrofluorimetric method for pharmaceutical and plasma analysis with greenness and whiteness assessment. BMC Chemistry, 20(1), Article 211. https://doi.org/10.1186/s13065-026-01951-6

Image Credits: AI Generated

DOI: 10.1186/s13065-026-01951-6

Keywords: delafloxacin, spectrofluorimetry, FMOC-Cl, fluorescence derivatization, pharmaceutical analysis, human plasma, green analytical chemistry, white analytical chemistry, method validation, BMC Chemistry, Unlocking, fluorescence