Background: This study was designed to develop a reliable method for simultaneous quantitation
of Citalopram (CIT) and its main active metabolite, Desmethylcitalopram (DCIT), in saliva of
patients undergoing treatment with CIT.
Methods: To compare two procedures of saliva purification, Solid-Phase (SPE) and Liquid-Liquid
(LLE) extractions, saliva samples obtained from healthy volunteers were spiked with adequate quantities
of CIT and DCIT. Different cartridges were used for SPE, while dichloromethane for LLE. Chromatographic
separation and quantitation were carried out by UHPLC with DAD detector using a C-18
column and a mixture of acetonitrile and redistilled water (37:63, v:v) with the addition of formic acid
(pH 3.5) as a mobile phase.
Results: A comparison of both purification procedures showed that the most satisfactory results were
obtained by SPE using Discovery C18 cartridge and redistilled water with formic acid (pH 3.5) as a
washing solvent. Dichloromethane proved to be the best extractant in LLE. Both procedures enabled the
separation of analytes from human saliva with high precision and recovery.
Conclusions: Validation of the developed UHPLC procedure revealed that, regardless of how the sample
was purified, the method was characterized by good linearity (between 10 and 1000 ng/mL), sensitivity,
reproducibility, specificity and low values of limits of detection and quantitation. The limits of
quantitation were 4.0 and 8.0 ng/mL for SPE and LLE, respectively. The efficiency of the method in
therapeutic drug monitoring of CIT and DCIT in saliva of patients was confirmed.