Stereoselective determination of citalopram and desmethylcitalopram in human plasma and breast milk by liquid chromatography tandem mass spectrometry

J Pharm Biomed Anal. 2016 Nov 30;131:233-245. doi: 10.1016/j.jpba.2016.08.014. Epub 2016 Aug 20.


A high performance liquid chromatography (HPLC) tandem mass spectrometry (MS/MS) method was developed for the simultaneous, stereoselective quantification of the antidepressant citalopram and its active metabolite desmethylcitalopram in human plasma and breast milk. Sample preparation was performed by a two-step approach, including generic protein precipitation with acetonitrile followed by solid phase extraction. Enantiospecific separation of analytes was achieved on a Phenomenex® Lux Cellulose-2 column (4.6mm×150mm; 5μm), using reversed phase chromatography conditions characterized by a gradient elution of ammonium acetate buffer (pH 9.0; 20mM) and acetonitrile at a flow rate of 0.6ml/min. The compounds were detected by a tandem quadrupole mass spectrometer equipped with an electrospray ionization source and operating in multiple reaction monitoring mode. The method was fully validated in both biological fluids over a large concentration range of 0.1-100ng/ml for S-(+)- and R-(-)-citalopram, and 0.3-100ng/ml for S-(+)- and R-(-)-desmethylcitalopram. Trueness (90.0-113.3% and 97.1-103.6%), repeatability (0.9-15.9% and 0.9-8.4%) and intermediate precision (1.3-17.8% and 0.9-9.6%) in plasma and breast milk, respectively, meet international guidelines for method validation. Internal standard-normalized matrix effects ranged between 99 and 101% and 98-105%, respectively. The accuracy profiles (total error of trueness and precision) were mostly within the acceptance limits for biological samples defined as ±30%. The method was successfully applied to patient samples in a clinical trial setting.

Keywords: Breast milk; Citalopram; Enantiomer; LC–MS/MS; Plasma; Quantification.

Publication types

  • Validation Study

MeSH terms

  • Chromatography, High Pressure Liquid / methods
  • Chromatography, Reverse-Phase / methods
  • Citalopram / analogs & derivatives*
  • Citalopram / blood*
  • Citalopram / metabolism*
  • Humans
  • Milk, Human / metabolism*
  • Reproducibility of Results
  • Solid Phase Extraction
  • Spectrometry, Mass, Electrospray Ionization / methods
  • Stereoisomerism*
  • Tandem Mass Spectrometry / methods


  • Citalopram
  • desmethylcitalopram