Fluorescence quenching of serum albumin by rifamycin antibiotics and their analytical application

In neutral medium, rifamycin antibiotics such as rifapentin (RFPT), rifampicin (RFP), rifandin (RFD) and rifamycin SV (RFSV) can bind with human serum albumin (HSA) and bovine serum albumin (BSA) to form complexes, resulting in the quenching of the intrinsic fluorescence (λex/λem = 285/355 nm) of the BSA and HSA. The quenching intensity (ΔF) is directly proportional to the concentration of the rifamycin antibiotics. Therefore, a new analytical method was established to determine trace rifamycin antibiotics. The method had fairly high sensitivity and the detecting limits (3σ) for RFPT, RFP, RFD and RFSV were 0.85, 0.98, 1.83, 1.89 ng/mL, respectively, for the HSA system and 0.76, 0.89, 1.55, 1.77 ng/mL, respectively, for the BSA system. All relative standard deviations (RSDs) were