Azar Pazhohan - Infertility center of Academic Center for Education, Culture and Research, East Azarbaijan, Tabriz, Iran
Mohammad Reza Afshar Mogaddam - Food and Drug Safety Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
Fardin Amidi - Department of Anatomy, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
Sajjad Jafarzadeh - Infertility center of Academic Center for Education, Culture and Research, East Azarbaijan, Tabriz, Iran
Mir Ali Farajzadeh - Department of Analytical Chemistry, Faculty of Chemistry, University of Tabriz, Tabriz, Iran. Engineering Faculty, Near East University, ۹۹۱۳۸ Nicosia, North Cyprus, Mersin ۱۰, Turkey

In this study, a dispersive liquid–liquid microextraction method using an extraction solvent lighter than water has been developed for the extraction and preconcentration of cholecalciferol and calcifediol from plasma samples followed by high performance liquid chromatography determination. Initially, acetonitrile and sodium chloride (NaCl) are added into the plasma as an extraction solvent and a salting–out agent, respectively. After manual shaking, the mixture is centrifuged. In the presence of sodium chloride, a two–phase system is formed. Then a portion of the upper phase is removed and mixed with n–hexane at µL–level and rapidly injected into distilled water by a syringe. In this process, the analytes are extracted into the fine droplets of n–hexane (as an extraction solvent). Under optimal conditions, enrichment factor was obtained ۹۲ and ۹۴ for calcifediol and cholecalciferol, respectively. The intra– (n=۶) and inter–day (n=۴) precisions were less than or equal to ۸.۱% at a concentration of ۱۰ ng mL–۱ of each analyte. Finally, this method was applied to the analysis of the analytes in human plasma samples.

Cholecalciferol, Calcifediol, High performance liquid chromatography, Human plasma