NBD-F (4-Fluoro-7-nitrobenzofurazan) is a fluorescent derivatization agent used for amino acid analysis.

NBD-F for quantification of colistin sulfate in rat plasma
1. Sample preparation: Colistin sulfate (including CLA and CLB) was extracted from rat plasma using a solid phase extraction (SPE) C18 column.
2. Reaction with NBD-F: The extracted colistin sulfate was reacted with 2 mM NBD-F and 10 mM boric acid buffer (pH 9.5).
3. Heating reaction: The reaction mixture was heated at 60°C for 5 minutes to promote the derivatization reaction.
4. HPLC analysis: The derivatization products were analyzed using reversed-phase high performance liquid chromatography (HPLC) combined with fluorescence detection.
5. Quantitative analysis: The peaks of CLA and CLB were quantified using appropriate standards. The lower limit of quantification for CLA and CLB was 0.05 μg/mL.