QUENCHING OF CERENKOV RADIATION FROM NATURALLY OCCURRING 40K BY DYES AS PHOTOMETRIC TECHNIQUE

Abstract

The beta emitter 40K isotope contained in KCl solutions, produces photons known as Cerenkov radiation measurable by liquid scintillation spectrometry. A set of dyestuffs and metal ion complexes showed quenching effects against Cerenkov light. Studied systems follow the Stern-Volmer equation. Counting ratios<img width=33 height=33 src="../img/revistas/rbq/v29n1/v29n1a08-1.jpg" alt="Descripción: C:\SciELO\serial\rbq\v29n1\img\revistas\rbq\v29n1\v29n1a08-1.jpg">vs. quencher concentration [Q], are linear, yielding Ks.v constants. High Ks.v values indicate highly quenched systems. Congo red and Methylene blue have<img width=33 height=33 src="../img/revistas/rbq/v29n1/v29n1a08-2.jpg" alt="Descripción: C:\SciELO\serial\rbq\v29n1\img\revistas\rbq\v29n1\v29n1a08-2.jpg">values 20.0xl0(4) M"¹ and 2.27xl0(4) M"¹ respectively. Crystal violet does not act as quenching agent in the range up to O.lrnM, and has a lowest<img width=33 height=33 src="../img/revistas/rbq/v29n1/v29n1a08-3.jpg" alt="Descripción: C:\SciELO\serial\rbq\v29n1\img\revistas\rbq\v29n1\v29n1a08-3.jpg">value, about 10"4 M"¹. There are linear correlations between visible absorbances at<img width=33 height=33 src="../img/revistas/rbq/v29n1/v29n1a08-4.jpg" alt="Descripción: C:\SciELO\serial\rbq\v29n1\img\revistas\rbq\v29n1\v29n1a08-4.jpg">and counting ratios<img width=33 height=33 src="../img/revistas/rbq/v29n1/v29n1a08-5.jpg" alt="Descripción: C:\SciELO\serial\rbq\v29n1\img\revistas\rbq\v29n1\v29n1a08-5.jpg"> Neither inorganic colorless salts as lead nitrate or zinc nitrate, nor pure solvents as acetonitrile, acetone, methanol and ethyl acetate showed quenching properties. As a result, a procedure suitable for dyestuff determinations based on quenching of Cerenkov radiation has been accomplished.

The beta emitter 40K isotope contained in KCl solutions, produces photons known as Cerenkov radiation measurable by liquid scintillation spectrometry. A set of dyestuffs and metal ion complexes showed quenching effects against Cerenkov light. Studied systems follow the Stern-Volmer equation. Counting ratios<img width=33 height=33 src="../img/revistas/rbq/v29n1/v29n1a08-1.jpg" alt="Descripción: C:\SciELO\serial\rbq\v29n1\img\revistas\rbq\v29n1\v29n1a08-1.jpg">vs. quencher concentration [Q], are linear, yielding Ks.v constants. High Ks.v values indicate highly quenched systems. Congo red and Methylene blue have<img width=33 height=33 src="../img/revistas/rbq/v29n1/v29n1a08-2.jpg" alt="Descripción: C:\SciELO\serial\rbq\v29n1\img\revistas\rbq\v29n1\v29n1a08-2.jpg">values 20.0xl0(4) M"¹ and 2.27xl0(4) M"¹ respectively. Crystal violet does not act as quenching agent in the range up to O.lrnM, and has a lowest<img width=33 height=33 src="../img/revistas/rbq/v29n1/v29n1a08-3.jpg" alt="Descripción: C:\SciELO\serial\rbq\v29n1\img\revistas\rbq\v29n1\v29n1a08-3.jpg">value, about 10"4 M"¹. There are linear correlations between visible absorbances at<img width=33 height=33 src="../img/revistas/rbq/v29n1/v29n1a08-4.jpg" alt="Descripción: C:\SciELO\serial\rbq\v29n1\img\revistas\rbq\v29n1\v29n1a08-4.jpg">and counting ratios<img width=33 height=33 src="../img/revistas/rbq/v29n1/v29n1a08-5.jpg" alt="Descripción: C:\SciELO\serial\rbq\v29n1\img\revistas\rbq\v29n1\v29n1a08-5.jpg"> Neither inorganic colorless salts as lead nitrate or zinc nitrate, nor pure solvents as acetonitrile, acetone, methanol and ethyl acetate showed quenching properties. As a result, a procedure suitable for dyestuff determinations based on quenching of Cerenkov radiation has been accomplished.