Study of solvent extraction of atomoxetine from aqueous solutions and biological fluids

This article presents the systematic study of the solvent extraction of an antidepressant Atomoxetine and optimization of the drug isolation methods from blood and urine. The dependence of the extraction recovery of Atomoxetine from aqueous solutions on the type of the organic solvent, pH of the aqueous medium and the presence of a salting-out agent was determined. Chloroform, methylene chloride, 1,2-dichloroethane, diethyl ether, ethyl acetate, tetrachloromethane, benzene, toluene, hexane were tested as organic extragents. The quantitative determination of Atomoxetine was performed by the UV-spectrophotometric method. The maximum extraction recovery value was of 28% at pH of 13 for chloroform. The extraction recovery with diethyl ether at pH of 1–2 was the lowest and equal to 0.2%, that makes possible to recommend this solvent for the extraction purification from co-extractive components of the biological matrix. To increase the extraction recovery sodium chloride and ammonium sulphate were used as salting-out agents. The maximum value of 89% in the extraction recovery of Atomoxetine was obtained for chloroform at pH of 11–12 in the aqueous phase saturation with ammonium sulphate. Recovery values of the solvent drug extraction were of 38.8% (RSD 8.7%) and 69.3% (RSD 6.7%) from blood and urine, respectively. Precipitation of blood cells by trichloroacetic acid (in sample preparation of blood), back-extraction and TLC clean-up step were incorporated into the sample preparation scheme to eliminate the extraction of the matrix components. The results obtained could be used in toxicological study of biological samples for presence of Atomoxetine.