Publications
High precision measurement of variations in calcium isotope ratios in urine by multiple collector inductively coupled plasma mass spectrometry
Jennifer L. L. Morgan, Gwyneth W. Gordon, Ruth C. Arrua, Joseph L. Skulan, Thomas D. Bullen, Ariel D. Anbar; Analytical Chemistry, 2011, 83 (18), pp 6956-6962
Abstract:
We describe a new chemical separation method to isolate Ca from other matrix elements in biological samples, developed with the long-term goal of making high precision measurement of natural stable Ca isotope variations a clinically applicable tool to assess bone mineral balance. A new two-column procedure utilizing HBr achieves the purity required to accurately and precisely measure two Ca isotope ratios (44Ca/42Ca and 44Ca/43Ca) on a Neptune multiple collector inductively coupled plasma mass spectrometer(MC-ICPMS) in urine. Purification requirements for Sr, Ti, and K (Ca/Sr > 10 000; Ca/Ti > 10 000 000; and Ca/K > 10) were determined by addition of these elements to Ca standards of known isotopic composition. Accuracy was determined by (1) comparing Ca isotope results for samples and standards to published data obtained using thermal ionization mass spectrometry (TIMS), (2) adding a Ca standard of known isotopic composition to a urine sample purified of Ca, and (3) analyzing mixtures of urine samples and standards in varying proportions. The accuracy and precision of δ44/42Ca measurements of purified samples containing 25 μg of Ca can be determined with typical errors less than (0.2% (2σ).
Fe Isotope Fractionation during Equilibration of Fe−Organic Complexes
Jennifer L. L. Morgan, Jochen Nuester, Laura E. Wasylenki, Ariel D. Anbar;
Environmental Science & Technology, 2010, 44 (16), pp 6095–6101
Abstract:
Despite their importance in the environment, few studies have investigated Fe isotope effects involving Fe-organic complexes. We investigated the fractionation of Fe isotopes during equilibration of pairs of Fe-organic ligand complexes to determine the relationship between isotope fractionation and ligand binding affinity. Previous experimental (Dideriksen et al., 2008, EPSL 369:280-290) and theoretical (Domagal-Goldman et al., 2009, Geochim. Cosmochim. Acta 73:1-12) studies disagreed on the sense of fractionation between Fe-desferrioxamine B (Fe-DFOB) and Fe(H2O)63+. Using a new experimental technique that allows physical separation of the two Fe-ligand pools without the need to induce precipitation, we measured the equilibrium fractionations between Fe-DFOB (log K = 30.6) and (1) Fe bound to ethylenediaminetetraacetic acid (EDTA, log K = 25.5, Δ56/54FeFe-DFOB-FeEDTA ≈ 0.02‰) and (2) Fe bound to oxalate (logK=18.6, Δ56/54FeFe-DFOB-FeOx = 0.20 ‰). Taken together, our results and those of Dideriksen et al. (2008) yield a positive correlation between measured fractionation factors and the Fe-binding affinity (log K) of the ligands. This correlation strongly supports the experimental results of Dideriksen et al. (2008). Additionally, the observed correlation between fractionation and log K provides a simple empirical tool that may be used to predict fractionation factors for Fe-ligand complexes not yet studied experimentally.
Distinctive Heavy Metal Composition of Pancreatic Juice in Patients with
Pancreatic Carcinoma
Patricia E. Carigan, Joseph G. Hentz, Gwyneth Gordon, Jennifer L. Morgan,
Massimo Raimondo, Ariel D. Anbar, and Laurence J. Miller
(2007) Cancer Epidemiol Biomarkers Prev, 16(12). 2656 – 2663.
Abstract:
Epidemiologic studies have shown the health risks of exposure to cigarette smoke and air pollution, with heavy metal composition implicated as contributing to both. Environmental exposure to cigarette smoke has been epidemiologically associated with pancreatic cancer, but the pathophysiologic basis for this is not yet clear. In the current work, we have used inductively coupled plasma mass spectrometry to quantify the metal composition of pancreatic juice collected in response to secretin stimulation in successive patients evaluated for abdominal pain (35 with pancreatic cancer, 30 with chronic pancreatitis, and 35 with normal pancreas). Indeed, metal composition of pancreatic juice was distinctive in patients with pancreatic cancer relative to those without such a cancer. The metal concentrations that were found to have the strongest association with pancreatic cancer were chromium, selenium, and molybdenum, with 1 SD increases in the concentrations of each associated with substantial increases in the odds of having pancreatic cancer relative to those in patients with normal pancreas (210%, 160%, and 76%, respectively). Of note, elevations in concentrations of chromium and selenium did not correlate in individuals, whereas those having a 1 SD increase in the sum of the concentrations of these two metals in their pancreatic juice had a 480% increase in the odds of having pancreatic cancer. Elevations of nickel and zinc correlated with elevated chromium in individuals, with each of these metals known to be present in cigarette smoke, whereas other recognized metal components of cigarette smoke were not elevated. An understanding of why these metals are elevated in pancreatic juice and what effects they might have on pancreatic cells may have important implications for the diagnosis, treatment, and even prevention of pancreatic cancer.
http://cebp.aacrjournals.org.ezproxy1.lib.asu.edu/content/16/12/2656
2-(4-tert Butylbenzyl)-3-phenylinden-1-one
J.W. Karban, J. L. Morgan, J.M. Dees, and K.K. Klausmeyer (2004).
Acta Cryst. E60, o2304-o2305.
Abstract:
The title compound, C26H24O, was obtained from the reaction of 2-[(4-tert-butyl)phenylmethyl]-1,3-diphenylpropane-1,3-dione with acetic anhydride. The reaction yielded 92% of the product. The crystal structure confirms the formation of the five-membered ring from the parent dione.
http://journals.iucr.org/e/issues/2004/12/00/er6005/index.html