Dysprosium determination

Time-resolved approaches for multi-analyte immunoassays have been described recently. Simultaneous determination of LH, follicle stimulating hormone (FSH), hCG, and prolactin (PRL) in a multisite manual strip format has been reported. 88 Four microtiter wells are attached to a plastic strip, two-by-two and back-to-back, such that the wells can be read on a microtiter plate reader. In a quadruple-label format, the simultaneous quantitative determination of four analytes in dried blood spots can be done using europium, samarium, dysprosium, and terbium. 89 In this approach, thyroid-stimulating hormone, 17-a-hydroxyprogesterone, immunoreactive trypsin, and creatine kinase MM (CK-MM) isoenzyme are determined from dried blood samples spotted on filter paper in a microtiter well coated with a mixture of antibodies. Dissociative fluorescence enhancement of the four ions using cofluorescence-based enhancement solutions enables the time-resolved fluorescence of each ion to be measured through four narrow-band interference filters. 

Figure 6) for the major portion of the precipitate was about 3.2 cm per min. Fines, however, settled at about 2.0 cm per min. The volume of precipitate-slurry was determined to be 3.6 L per mole of dysprosium. 

For example, the isotopic composition and the atomic weight of neodyminm," dysprosium and erbium have been determined using synthetic mixtnres prepared gravimetrically from highly enriched isotopes of neodymium in the form of oxides of weU defined pnrity by TIMS. No natnral isotopic variation was found in terrestrial neodymium, dysprosium or erbium samples. These isotopic compositions of Dy and Er measnred by TIMS are accepted as the best measurements from a single terrestrial source as noted in the table of isotopic composition of elements, 2001. °... 

Notice that Moseley had made a minor mistake in the atomic number determinations of both holmium and dysprosium. The atomic number of holmium is namely 67, and dysprosium has an atomic number of 66. It also appears that Moseley attached some credence to the investigation of Auer von Welsbach who had demonstrated the complexity of thulium in 1911 by splitting it into three components. Moseley had incorporated two of these components (Tml and Tmll) in his atomic number sequence. Moseley therefore ascribed Urbain s neo-ytterbium and lutetium too high an atomic number (in reality the atomic numbers of ytterbium and... 

Lanthanide (III) Oxides. The lanthanide(III) oxides will be used to illustrate the present breadth of our most extensive knowledge of the chemical thermodynamics of lanthanide compounds. Cryogenic heat capacities of hexagonal (III) lanthanum, neodymium, and samarium oxides, together with those of cubic (III) oxides of gadolinium, dysprosium, holmium, erbium, and ytterbium, have been reported (90, 91, 195). In addition, those of thulium, lutetium, and a composition approaching that of cerium (III) oxide have also been determined, and five well-characterized compositions between PrOi.714 and PrOi.833 are currently under study (J93). 

Cerny and Kovar (241) determined the heat of interaction with vacuum-evaporated films of dysprosium and yttrium at room temperature. These metals yielded high heats of adsorption of 960 and 1060 kj mol", respectively. It was suggested that the oxygen molecules undergo dissociative adsorption on the surface and penetrate into the subsurface, where they form strong bonds to the metal. 

Activation analysis was first applied by von Hevesy and Levi two years after the discovery of artificial radioactivity (38). Determination of 0.1% dysprosium in rare earth mixtures was made by activation with neutrons from a 300-millicurie radium emanation-beryllium neutron source. The 2.3-hr half-life induced activity due to Dy was compared with that induced in mixtures of known dysprosium content. A similar method was used to determine europium in gadolinium. 

Seven naturally occurring isotopes of dysprosium are known. Isotopes are two or more forms of an element. Isotopes differ from each other according to their mass number. The number written to the right of the element s name is the mass number. The mass number represents the number of protons plus neutrons in the nucleus of an atom of the element. The number of protons determines the element, but the number of neutrons in the atom of any one element can vary. Each variation is an isotope. The four most abundant isotopes of dysprosium are dysprosium-161, dysprosium-162, dysprosium-163, and dysprosium-164. 

The lanthanide or rare earth elements (atomic numbers 57 through 71) typically add electrons to the 4f orbitals as the atomic number increases, but lanthanum (4f°) is usually considered a lanthanide. Scandium and yttrium are also chemically similar to lanthanides. Lanthanide chemistry is typically that of + 3 cations, and as the atomic number increases, there is a decrease in radius for each lanthanide, known as the lanthanide contraction. Because bonding within the lanthanide series is usually predominantly ionic, the lanthanide contraction often determines the differences in properties of lanthanide compounds and ions. Lanthanide compounds often have high coordination numbers between 6 and 12. see also Cerium Dysprosium Erbium Europium Gadolinium Holmium Lanthanum Lutetium Praseodymium Promethium Samarium Terbium Thulium Ytterbium. 

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