Showing papers by "Mark L. Dietz published in 2015"
TL;DR: The chosen analytical conditions using a 90:10 acetonitrile-ammonium formate buffer mobile phase on a high-purity, unmodified silica column were found to be efficient, robust, and sensitive for the determination of ILs in a variety of solutions.
26 citations
TL;DR: Unexpectedly the performance of these materials was not uniformly better than that of a conventional EXC resin, an apparent result of the greater viscosity of the ionic liquids and the lower solubility of the crown ether in ILs versus conventional organic solvents.
23 citations
TL;DR: In this article, a laboratory experiment is described in which students compare two methods for the determination of the calcium content of commercial dietary supplement tablets, and students pool their data with classmates and perform a statistical analysis to determine whether the average values of the calculated calcium content obtained by the two methods are equivalent.
Abstract: A laboratory experiment is described in which students compare two methods for the determination of the calcium content of commercial dietary supplement tablets. In a two-week sequence, the sample tablets are first analyzed via complexometric titration with ethylenediaminetetraacetic acid and then, following ion exchange of the calcium ion present for hydronium ion, by acid–base titration with sodium hydroxide. Upon completion of the laboratory work, students pool their data with classmates and perform a statistical analysis to determine whether the average values of the calcium content obtained by the two methods are equivalent. When taken together with such considerations as analysis time, accuracy, simplicity and ease of use, susceptibility to interference, and waste generation, these results enable the students to evaluate the relative merit of the two approaches to calcium determination. In so doing, they are introduced to an important aspect of “real-world” chemical analysis, namely, selection of th...
7 citations
TL;DR: In this article, sol-gel chemistry has been employed to prepare sorbents in which DtBuCH18C6 is encapsulated in a silica matrix, and the resultant materials have been evaluated for their ability to retain strontium ion and compared to a commercially available extraction chromatographic (EXC) resin.
Abstract: Extraction chromatography employing an inert polymeric support impregnated with a crown ether (typically, 4,4’,(5’)-di-(tert-butylcyclohexano)-18-crown-6 (DtBuCH18C6)), either neat (i.e., undiluted) or as a solution in 1-octanol, has previously been shown to provide an effective means for the isolation of radiostrontium from a variety of sample types for subsequent determination. In this study, sol-gel chemistry has been employed to prepare sorbents in which DtBuCH18C6 is encapsulated in a silica matrix. The resultant materials have been evaluated for their ability to retain strontium ion and compared to a commercially available extraction chromatographic (EXC) resin. Certain of the new materials are shown to provide uptake efficiencies comparable to those obtained with the commercial resins, although unless a porogen is employed, the kinetics of strontium uptake are significantly slower. In contrast to conventional EXC materials, however, strontium uptake by DtBuCH18C6-loaded glasses does not increase in...
2 citations