title: Determination of rifaximin in rat serum by ionic liquid based dispersive liquid-liquid microextraction combined with RP-HPLC.
abstract: An efficient and environmental friendly ionic liquid based dispersive liquid-liquid microextraction procedure was optimized for determination of rifaximin in rat serum by reverse phase high-performance liquid chromatography. The effect of ionic liquids, dispersive solvents, extractant/disperser ratio, and salt concentrations on sample recovery and enrichment factors were studied. Among the five ionic liquids studied in the present investigation, 1-butyl-3-methylimidazolium hexafluorophosphate was found to be most effective for extraction of rifaximin. The recovery was found to be more than 98% using 1-butyl-3-methylimidazolium hexafluorophosphate and methanol as extraction and dispersive solvents, at an extractant/disperser ratio of 0.43. The recovery was further enhanced to 99.5% by the addition of 5.0% NaCl solution. A threefold enhancement in detection limit was achieved when compared to protein precipitation. The ionic liquid containing the extracted rifaximin was directly injected into HPLC system. The linear relationship was observed in the range of 0.03-10.0 μg/mL with the correlation coefficient (r(2)) 0.9998. Limits of detection and quantification were found to be 0.01 and 0.03 μg/mL, respectively. The relative standard deviation was 2.5%. The method was validated and applied to study pharmacokinetics of rifaxmin in rat serum.
authors: Analytical Chemistry Division, D-215, Discovery Laboratory, Indian Institute of Chemical Technology, Tarnaka, Hyderabad, India. rnrao@iict.res.in
authors: Ramisetti Nageswara
authors: RN
authors: Rao
authors: Rajavarapu Mastan
authors: RM
authors: Vali
authors: Alamanda Vara Prasada
authors: AV
authors: Rao
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000097:blood* / Q000302:isolation & purification* / Q000627:therapeutic use; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D056148:Chromatography, Reverse-Phase / Q000379:methods; D006501:Hepatic Encephalopathy / Q000097:blood / Q000188:drug therapy; D006801:Humans; D052578:Ionic Liquids / Q000737:chemistry; D059627:Liquid Phase Microextraction / Q000295:instrumentation / Q000379:methods*; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D012294:Rifamycins / Q000097:blood* / Q000302:isolation & purification* / Q000627:therapeutic use; D000078262:Rifaximin
chemical_list: D000900:Anti-Bacterial Agents; D052578:Ionic Liquids; D012294:Rifamycins; D000078262:Rifaximin