Ion-pair reagents (IPR) are used in reversed-phase liquid chromatography (RP-LC) and has effectively separated ionic or ionizable analytes. 

Successful applications of Ion-pair Reagents

Single- and double- stranded RNA / biological or synthetic (2011) [1]

Stationary Phase: Non-porous polymeric columns and monolithic polymeric capillary columns

Ion-Pair Reagent: Various traditional or volatile amine cation salts

Detector: Fluorescent-based assays or MS


  • High-resolution separations of short and long RNA molecules
  • Less than 10-minute separations

Metformin-alogliptin, and Metformin-repaglinide binary tablets (2019) [2]

Stationary Phase: Inertsil ODS column (250 mm, 4.6 mm, 5 μm)

Mobile Phase: sulfonateAcetonitrile: Phosphate buffer: Water

Ion-Pair Reagent: 0.3 % sodium heptane

Detector: UV


  • Good recoveries achieved
  • Sharp and well separated peaks
  • Accurate, selective, and ecofriendly
  • Method applicable in QC laboratories for the routine analysis of these drugs

Lactose, glucose, and galactose / original skim milk (2012) [3]

Stationary Phase: C18 column

Ion-Pair Reagent: Tetrabutylammonium hydrogen sulphate

Detector: UV and fluorescence


  • Accurate and reproducible results
  • Short retention times
  • Simpler and quicker preparation compared to gas chromatography (no need to convert sugars into volatile derivatives)
  • Low limit of quantification (LOQ) and limit of detection (LOD)

Nitrate and thiocyanate / natural water samples (2012) [4]

Stationary Phase: C18 column

Mobile Phase: 30:70 Methanol:Water (isocratic)

Ion-Pair Reagent: 0.08 mM Hexadecyltrimethyl-ammonium bromide (HTAB)

Detector: UV


  • Simple
  • Sensitive, accurate, and reproducible



  • Dickman, M. J. Ion Pair Reverse-Phase Chromatography: A Versatile Platform for the Analysis of RNA. Chromatography Today. 2011. 22 – 26.
  • Mahrouse, M. A., Lamie, N. T. Experimental design methodology for optimization and robustness determination in ion pair RP-HPLC method development: Application for the simultaneous determination of metformin hydrochloride, alogliptin benzoate and repaglinide in tablets. Microchemical Journal 2019, 147, 691-706.
  • Erich, S., Anzmann, T., Fischer, L. Quantification of lactose using ion-pair RP-HPLC during enzymatic lactose hydrolysis of skim milk. Food Chemistry 2012,135(4), 2393-2396.
  • Soleimani, M., Yamini, Y., Rad, F. M. A simple and high resolution ion-pair HPLC method for separation and simultaneous determination of nitrate and thiocyanate in different water samples. J. of Chromatographic Science 2012, 50(9), 826-830.

    Related Articles

    Ion-pair Reagent (IPR)

    IPR Method Development Guide


    By Qinling Li


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