HPLC determination of rifampicin and related compounds in pharmaceuticals using monolithic column

A rapid, sensitive and reproducible HPLC method using C18 monolithic column was developed and validated for the analysis of rifampicin (RIF) and its four related compounds, including rifampicin quinone (RQ), rifamycin SV (SV), rifampicin N-oxide (RNO) and 3-formylrifamycin SV (3-FR). Chromatographic separation was achieved by using the mixture of methanol-acetonitrile-monopotassium phosphate (0.075 M)-citric acid (1.0M) (28:30:38:4, v/v) as the mobile phase at a flow rate of 2 mL/min and with UV detection at 254 nm. Calibration curves were obtained in the concentration ranges of 1-40 microg/mL for SV, RNO and 3-FR, 1.5-60 microg/mL for RQ and 5-200 microg/mL for RIF. Limit of quantitation (LOQ) was determined to be 1 microg/mL and the limit of detection (LOD) was 0.2 microg/mL for all studied compounds with a 10 microL injection. The intra-day R.S.Ds. and inter-day R.S.Ds. for the above five compounds were all less than 2.5%. The recoveries of rifampicin from placebo tablets were from 99.7% to 100.5%. The total run time was less than 11 min, as opposed to around 60 min by using C18 particle-packed column. In conclusion, by this developed method, RIF and its related compounds can be determined rapidly with good precision and accuracy in pharmaceuticals.