A comparative and simultaneous analysis of indoxyl sulfate and sodium butyrate in human plasma by SPE and HPLC methods for kidney patients

A comparison of high-performance liquid chromatography (HPLC) and solid-phase extraction (SPE) methods is carried out for the simultaneous analysis of indoxyl sulfate and sodium butyrate in plasma using Phenyl (250 x 4.6 mm; 5 mu m) and SunShell (150 x 4.6 mm, 2.6 mu m) columns with mobile phases ammonium acetate (20 mM)-ACN (95:5, v/v) and water-ACN (90:10), respectively. The values of the retention, separation and resolution factors for indoxyl sulfate and sodium butyrate were 3.1, 1.29 and 2.0 with phenyl and 1.0, 1.55 and 1.60 with SunShell columns. The values of the theoretical plates were in the range of 650 to 1600 while the tailing factors were 0.98 to 1.0. The limits of the detection and quantification of sodium butyrate and indoxyl sulfate were 0.1-1.9 and 0.43-9.2 mu g with these columns. The hydrogen bondings and pi-pi interactions were responsible for the separation of these molecules. The multi-wall carbon nanotubes (MWCNTs) served as a good sorbent in SPE extraction. The developed SPE and HPLC methods were quick, robust, exact and economic for the analysis of indoxyl sulfate and sodium butyrate. The reported SPE and HPLC methods can be useful to determine the reported molecules in plasma.