Determination of ethambutol by a sensitive fluorescent probe

The competitive reaction between ethambutol and two fluorescent probes (i.e., berberine and palmatine) for occupancy of the cucurbit[7]uril (CB[7]) cavity was studied by spectrofluorometry. The CB[7] reacts with these probes to form stable complexes, and the fluorescence intensity of the complexes is greatly enhanced. In addition, the excitation and emission wavelengths of their complexes moved to wavelengths of 343 nm and 495 nm, respectively. However, the addition of ethambutol dramatically quenches the fluorescence intensity of the two complexes. Accordingly, a couple of new fluorescence quenching methods for the determination of ethambutol were established. The methods can be applied for quantifying ethambutol. A linear relationship between the fluorescence quenching values (ΔF) and ethambutol concentration exists in the range of 5.0–1000.0 ng mL−1, with a correlation coefficient (r) of 0.9997. The detection limit is 1.7 ng mL−1. The fluorescent probe of berberine has higher sensitivity than palmatine. This paper also discusses the mechanism of fluorescence indicator probes.

A sensitive method for the detection of ethambutol based on fluorescence quenching (ΔF) of cucurbit[7]uril (CB[7])/berberine (BRH) was developed. For a specific range of concentrations, the ΔF values show a good linear relationship with ethambutol. It has a detection limit of 1.7 ng mL−1. The probe can be applied to bulk and biological fluids.Figure optionsDownload as PowerPoint slideHighlights
► We examine berberine and palmatine as fluorescent probes by spectrofluorometry.
► Establishing new fluorescence quenching methods for the determination of ethambutol.
► A linear relationship exists in the range of 5–1000 ng mL−1, the detection limit is 1.7 ng mL−1.
► Using for determination of ethambutol in bulk and biological fluids.