Abstract: A method of producing sulfur-free nanoparticles involves growing yeast in a growth medium containing a source of an element in a bio-reducible oxidation state (e.g. Se(Vl), and, precipitating nanoparticles containing the element in a lower oxidation state (e.g. Se(O)) than the oxidation state of the element in the source. The method advantageously can provide substantially spherical nanoparticles at high production efficiencies.

Abstract: A comprehensive approach for interpretation of the multiple spiking isotope dilution results is described herein. It has now been found that a method of multiple spiking isotope dilution analysis for mass spectrometry is possible using an approach that permits precise and simultaneous characterization of m substances from a sample even if species inter-conversion (degradation and formation) has occurred prior to separation. Advantageously, initial and final amounts of involved analytes, conversion extent, conversion degree and rate constants from the results of a single quantitation experiment may be obtained with the present method. In a particularly advantageous embodiment, uncertainty in the characterization of the substances may be estimated more accurately by also estimating increase in the uncertainty due to inter-conversion of the analytes.

Abstract: A comprehensive approach for interpretation of the multiple spiking isotope dilution results is described herein. It has now been found that a method of multiple spiking isotope dilution analysis for mass spectrometry is possible using an approach that permits precise and simultaneous characterization of m substances from a sample even if species inter-conversion (degradation and formation) has occurred prior to separation. Advantageously, initial and final amounts of involved analytes, conversion extent, conversion degree and rate constants from the results of a single quantitation experiment may be obtained with the present method. In a particularly advantageous embodiment, uncertainty in the characterization of the substances may be estimated more accurately by also estimating increase in the uncertainty due to interconversion of the analytes.

Abstract: A method of producing sulfur-free nanoparticles involves growing yeast in a growth medium containing a source of an element in a bio-reducible oxidation state (e.g. Se(V1), and, precipitating nanoparticles containing the element in a lower oxidation state (e.g. Se(O)) than the oxidation state of the element in the source. The method advantageously can provide substantially spherical nanoparticles at high production efficiencies.