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Villar M.,Radiopharmacy Service | Avivar J.,Sciware Systems S.L. | Avivar J.,University of the Balearic Islands | Ferrer L.,University of the Balearic Islands | And 3 more authors.
Analytical and Bioanalytical Chemistry | Year: 2015

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 father 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 acetone, 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 extractant and disperser, respectively. Off-line detection was performed 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. [Figure not available: see fulltext.] © 2015 Springer-Verlag Berlin Heidelberg

Villar M.,Radiopharmacy Service | Avivar J.,University of the Balearic Islands | Ferrer L.,University of the Balearic Islands | Galmes M.,Radiopharmacy Service | And 2 more authors.
Analytical Chemistry | Year: 2013

99mTc (6.0067 h half-life) is an artificial radionuclide largely used in diagnostic medicine. Its daughter 99Tc is a beta emitter of great concern because of its long half-life (2.111 × 105 years) and presumed mobile behavior in the environment. To monitor the 99Tc in urine from treated patients, an automatic Lab-on-valve (LOV) system for separation and preconcentration of 99Tc was developed. TEVA resin was selected since it retains pertechnetate ion selectively from diluted nitric acid solutions. After elution, 99Tc is detected using a liquid scintillation counting (LSC) detector. The present method has been successfully applied to urine samples with low 99Tc content (recoveries between 94-111%). The minimum detectable activity (MDA) of the developed method is 0.1 Bq or 1 Bq L-1 (expressed as activity concentration), when preconcentrating 100 mL of sample. The high durability of the resin, together with the low amount of resin required (32 mg), the good reproducibility (RSD 2%, n = 5) and the high extraction frequency (up to 12 h-1) makes of the present method an inexpensive, precise and fast useful tool for monitoring 99Tc in urine samples. © 2013 American Chemical Society.

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