Automatic in-syringe dispersive liquid–liquid microextraction of 99Tc from biological samples and hospital residues prior to liquid scintillation counting

Abstract

A new approach exploiting in-syringe dispersive liquid–liquid microextraction (DLLME) for 99Tc extraction and preconcentration from biological samples, i.e., urine and saliva, and liquid residues from treated patients is presented. 99Tc is a beta emitter with a long half-life (2.111×105 years) and mobility in the different environmental compartments. One of the sources of this radionuclide is through the use of its fathe r 99mTc in medical diagnosis. For the first time a critical comparison between extractants and disperser solvents for 99Tc DLLME is presented, e.g., tributyl phosphate (TBP), trioctylmethylammonium chloride (Aliquat®336), triisooctylamine (TiOA), as extractants in apolar solvents such as xylene and dodecane, and disperser solvents such as ace-tone, acetonitrile, ethanol, methanol, 1-propanol, and 2-propanol. The system was optimized by experimental design, and 22.5 % of Aliquat®336 in acetone was selected as extract-ant and disperser, respectively. Off-line detection was per-formed using a liquid scintillation counter. The present method has a 99Tc minimum detectable activity (MDA) of 0.075 Bq with a high extraction/preconcentration frequency (8 h−1). Urine, saliva, and hospital residues were satisfactorily analyzed with recoveries of 82–119 %. Thus, the proposed system is an automatic powerful tool to monitor the entry of 99Tc into the environment.