Tracers calcium

Johnston and Deiss (Jl) injected rats with °Ca a few hours before thyrocalcitonin administration. They found the expected reduction in the plasma calcium concentration, although its specific activity was higher in the thyrocalcitonin-treated group than in the controls this is consistent with an inhibition of release of unlabeled calcium from bone, but could not be explained on the basis of an increased outfiow of labeled calcium into tissue from the plasma. When tracer calcium was administered 10-14 days prior to thyrocalcitonin injection, the hormone produced a decrease in both stable and tracer calcium in the blood plasma, indicating an inhibition of calcium release from bone. In these animals having labeled bone calcium, increases in stable and radioactive plasma calcium resulted from the administration of parathyroid extract alone, although the simultaneous administration of parathyroid extract and thyrocalcitonin resulted in no net change in either stable or radioactive calcium. It was concluded that both hormones probably act on a similar metabolic compartment in bone. 

Glaser and Lichtenstein (G3) measured the liquid residence-time distribution for cocurrent downward flow of gas and liquid in columns of -in., 2-in., and 1-ft diameter packed with porous or nonporous -pg-in. or -in. cylindrical packings. The fluid media were an aqueous calcium chloride solution and air in one series of experiments and kerosene and hydrogen in another. Pulses of radioactive tracer (carbon-12, phosphorous-32, or rubi-dium-86) were injected outside the column, and the effluent concentration measured by Geiger counter. Axial dispersion was characterized by variability (defined as the standard deviation of residence time divided by the average residence time), and corrections for end effects were included in the analysis. The experiments indicate no effect of bed diameter upon variability. For a packed bed of porous particles, variability was found to consist of three components (1) Variability due to bulk flow through the bed... 

The amounts of the standard isotopic species and the tracer isotopic species are represented by X and X for the sample and the reference material. The reference substance is chosen arbitrarily, but is a substance that is homogeneous, available in reasonably large amounts, and measurable using standard analytical techniques for measuring isotopes (generally mass spectrometry). For instance, a sample of ocean water known as Standard Mean Ocean Water (SMOW) is used as a reference for and 0. Calcium carbonate from the Peedee sedimentary formation in North Carolina, USA (PDB) is used for C. More information about using carbon isotopes is presented in Chapter 11. 

Elution volume calibrations were performed using radioactive tracers of the rare earth elements and 133Ba, with atomic-absorption or flame-emission analysis of iron, sodium, potassium, calcium, and magnesium. As shown in Fig. 5.14, any barium added to the second columns is eluted at the start of the light rare earth element fraction . To ensure barium removal the sample can be put through the first column again. 

Tsunogai and Nozaki [6] analysed Pacific Oceans surface water by consecutive coprecipitations of polonium with calcium carbonate and bismuth oxychloride after addition of lead and bismuth carriers to acidified seawater samples. After concentration, polonium was spontaneously deposited onto silver planchets. Quantitative recoveries of polonium were assumed at the extraction steps and plating step. Shannon et al. [7], who analysed surface water from the Atlantic Ocean near the tip of South Africa, extracted polonium from acidified samples as the ammonium pyrrolidine dithiocarbamate complex into methyl isobutyl ketone. They also autoplated polonium onto silver counting disks. An average efficiency of 92% was assigned to their procedure after calibration with 210Po-210Pb tracer experiments. 

Figure 1. Schematic representation of the calcium mass spectrum in (a) natural materials, (b) a Ca- Ca tracer solution used for separating natural mass dependent isotopic fractionation from mass discrimination caused by thermal ionization, and (c) a typical mixture of natiwal calcium and tocer calcium used for analysis. The tracer solution has roughly equal amounts of Ca and Ca. In (c) the relative isotopic abundances are shown with an expanded scale. Note that in the mixed sample, masses 42 and 48 are predominantly from the tracer solution, and masses 40 and 44 are almost entirely from natural calcium. This situation enables the instrumental fractionation to be gauged from the Ca/ Ca ratio, and the natural fractionation to be gauged from the sample Ca/ Ca ratio.

Using the three measured ratios, Ca/ Ca, Ca/ " Ca and Ca/ " Ca, three unknowns can be solved for the tracer/sample ratio, the mass discrimination, and the sample Ca/ Ca ratio (see also Johnson and Beard 1999 Heuser et al. 2002). Solution of the equations is done iteratively. It is assumed that the isotopic composition of the Ca- Ca tracer is known perfectly, based on a separate measurement of the pure spike solution. Initially it is also assumed that the sample calcium has a normal Ca isotopic composition (equivalent to the isotope ratios listed in Table 1). The Ca/ Ca ratio of the tracer is determined based on the results of the mass spectrometry on the tracer-sample mixture, by calculating the effect of removing the sample Ca. This yields a Ca/ Ca ratio for the tracer, which is in general different from that previously determined for the tracer. This difference is attributed to mass discrimination in the spectrometer ion source and is used to calculate a first approximation to the parameter p which describes the instrumental mass discrimination (see below). The first-approximation p is used to correct the measured isotope ratios for mass discrimination, and then a first-approximation tracer/sample ratio and a first-approximation sample CeJ Ca... 

The radioactive isotope calcium-45 is deposited in bones and teeth as well as other plant and animal tissues. Because our bodies cannot distinguish between Ca-45 and the stable Ca-40, the radioactive isotope Ca-45 is used as a tracer to study diseased bone and tissue. At the same time, a massive overexposure to Ca-45 can displace the stable form of Ca-40 in animals and can cause radiation sickness or even death. 

Groundwater-inflow rates as calculated by the solute and isotope mass-balance methods for several northern Wisconsin lakes are listed in Table I. Dissolved calcium was used as the solute tracer because it is the constituent whose concentration differs the most between groundwater and precipitation, the two input components to be separated by the method. In addition, calcium is nearly conservative in the soft-water, moderately acidic to cir-cum-neutral lakes in northern Wisconsin. Results from the two methods agree relatively well, except for Crystal Lake, where groundwater-flow reversals are frequent. 

The isotope mass-balance method is not as useful for estimating groundwater-flow rates for groundwater-poor lakes as it is for lakes that receive substantial quantities of groundwater. Solute tracers, such as dissolved calcium, may be useful in assessing... 

Calcium resinate has been used in detonators with RDX in the form of a 50/50 mixt with graphite to the extent of 2% of the compn (Ref 2). In the invention of Clay and Sahlin (Ref 3), it comprises 7% of an igniter compn for tracer projs along with Sr02 (78%), Ba02 (4%), Pb02... 

Goans RE, Weiss GH, Abrams SA, Perez MD, Yergey AL. Calcium tracer kinetics show decreased irreversible flow to bone in glucocorticoid treated patients. Calcif Tissue Int 1995 56(6) 533-5. 

Reconstituted acid-soluble collagen from various mineralized and unmineralized tissues have been examined for their potential to pick up calcium and phosphate from buffered solutions, and for their capacity to induce nucleation of a mineral phase426-434. Some collagens were good, others poor catalysts428,429 and apatite deposition proceeded in the presence of soft as well as of hard tissue collagens. The uptake of calcium ions requires the presence of phosphate ions and vice versa the Ca/P ratio is close to that of apatite (1.5—1.8)431. Study of exchange reactions by isotope tracers between solvent und substrate revealed that in absence of either... 

Elmore, D., Bhattacharyya, M. H., Sacco-Gibson, N., and Peterson, D. P. (1990). Calcium-41 as a long-term biological tracer for bone resorption. Nucl. Instrum. Methods Phys. Res. B52 531-535. 

Bogoyavlenskaya, N.P. (1959). Study of calcium metabolism aimed to apply Ca45 as a tracer for fish (In Russian). Rybnoye Khozyaistvo 1959,1-55. 

Chloride behaves like an ideal tracer and is only affected by dispersion. Calcium is still not in solution even after a single exchange of all water within the column (shift = 40) as it is exchanged for Na and K. When all sodium has been removed from the exchanger, Ca can only be exchanged for K that leads to a peak in the K-concentration. Only after the water of the column has been exchanged about 2.5 times, the concentration of calcium increases at the outlet. 

Pritham patented pyrotechnic or projectile tracer ammunition containing salts of thorium and cerium, such as the nitrates, used with calcium resinate as a... 

---