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At least 127 records · Page 7Linked to original sources
PubMed1992

Triple-label beta liquid scintillation counting.

The detection of radioactive compounds by liquid scintillation has revolutionized modern biology, yet few investigators make full use of the power of this technique. Even though multiple isotope counting is considerably more difficult than single isotope counting, many experimental designs would benefit from using more than one isotope. The development of accurate isotope counting techniques enabling the simultaneous use of three beta-emitting tracers has facilitated studies in our laboratory using the multiple tracer indicator dilution technique for assessing rates of transmembrane transport and cellular metabolism. The details of sample preparation, and of stabilizing the liquid scintillation spectra of the tracers, are critical to obtaining good accuracy. Reproducibility is enhanced by obtaining detailed efficiency/quench curves for each particular set of tracers and solvent media. The numerical methods for multiple-isotope quantitation depend on avoiding error propagation (inherent to successive subtraction techniques) by using matrix inversion. Experimental data obtained from triple-label beta counting illustrate reproducibility and good accuracy even when the relative amounts of different tracers in samples of protein/electrolyte solutions, plasma, and blood are changed.

Animals↗
PubMed2004

Aqueous liquid scintillation counting with fluor-containing nanosuspensions.

A microemulsion comprised of water, Brij 78, pentanol and styrene into which PPO and bis-MSB had been dissolved was prepared. Polymerization of the styrene resulted in a suspension of fluor-containing polystyrene nanoparticles (<100 nm). After a concentration step, the aqueous nanosuspension was able to detect (14)C with counting efficiencies over 50% of those of a commercially available scintillation cocktail. Monte Carlo calculations demonstrated that the size and concentration of the nanoparticles were appropriate for optimum detection efficiency.

Carbon Radioisotopes↗
PubMed1995

Sequential determination of a combined gamma/beta and pure beta-emitter by gamma and liquid scintillation counting: application to the transport of metals across fish gills.

A combined gamma scintillation/liquid scintillation technique for the sequential determination of two radioactive tracers is described. The method was developed using a combined gamma/beta-emitter (57Co) and a pure beta-emitter (45Ca). First, the 57Co radioactivity was determined by counting the samples in a gamma scintillation analyzer in the energy region 80-165 keV. Next, the samples were counted in a liquid scintillation analyzer. Only one energy region was used to count both isotopes to maximize the counting efficiencies. From the difference between quenched and unquenched beta-spectra, the counting region was set from 0 to 256 keV. The counting efficiency was related to a quench-indicating parameter (tSIE) for both nuclides by fitting a rectangular hyperbola to the quench data. By subtracting the 57Co counts from the observed counts in the total window, 45Ca dpm values were obtained. It is shown that the method presented gives reliable and consistent results. The recoveries of both isotopes are independent of the quench level in a large tSIE range, although five times more radioactivity is required for 45Ca than for 57Co to obtain accurate and reproducible results. The method has been used to study mechanisms of metal transport across biological interfaces.

Animals↗