Tests, spectrometer

Special isotope ratio mass spectrometers are needed to measure the small variations, which are too small to be read off from a spectrum obtained on a routine mass spectrometer. Ratios of isotopes measured very accurately (usually as 0/00, i.e., as parts per 1000 [mil] rather than parts per 100 [percent]) give information on, for example, reaction mechanisms, dating of historic samples, or testing for drugs in metabolic systems. Such uses are illustrated in the main text. 

The helium leak detector is a common laboratory device for locating minute leaks in vacuum systems and other gas-tight devices. It is attached to the vacuum system under test a helium stream is played on the suspected leak and any leakage gas is passed into a mass spectrometer focused for the helium-4 peak. The lack of nearby mass peaks simplifies the spectrometer design the low atmospheric background of helium yields high sensitivity helium s inertness ensures safety and its high diffusivity and low adsorption make for fast response. 

Rheometric Scientific markets several devices designed for characterizing viscoelastic fluids. These instmments measure the response of a Hquid to sinusoidal oscillatory motion to determine dynamic viscosity as well as storage and loss moduH. The Rheometric Scientific line includes a fluids spectrometer (RFS-II), a dynamic spectrometer (RDS-7700 series II), and a mechanical spectrometer (RMS-800). The fluids spectrometer is designed for fairly low viscosity materials. The dynamic spectrometer can be used to test soHds, melts, and Hquids at frequencies from 10 to 500 rad/s and as a function of strain ampHtude and temperature. It is a stripped down version of the extremely versatile mechanical spectrometer, which is both a dynamic viscometer and a dynamic mechanical testing device. The RMS-800 can carry out measurements under rotational shear, oscillatory shear, torsional motion, and tension compression, as well as normal stress measurements. Step strain, creep, and creep recovery modes are also available. It is used on a wide range of materials, including adhesives, pastes, mbber, and plastics. 

Replacing one of these protons by chlorine as a test group gives (/ )-2-chloro-l-propanol replacing the other gives (.S)-2-chloro-l-propanol. Enantiotopic protons have the sane chemical shift, regardless of the field strength of the NMR spectrometer. 

In gas chromatography/mass spectrometry (GC/MS), the effluent from a gas chromatograph is passed into a mass spectrometer and a mass spectrum is taken every few milliseconds. Thus gas chromatography is used to separate a mixture, and mass spectrometry used to analyze it. GC/MS is a very powerful analytical technique. One of its more visible applications involves the testing of athletes for steroids, stimulants, and other performance-enhancing drugs. These drugs are converted in the body to derivatives called metabolites, which are then excreted in the... 

The power of the new spectrometer to reveal configurations of difficult cyclitols or sugars was first tested with mt/o-inositol (2), using deuterium oxide as solvent. At 60 or 100 MHz. the one equatorial and five axial protons appear to have different chemical shifts as shown by Lemieux in 1956 with a 40 MHz. instrument (14,15). However, since the five-proton axial signal could not be resolved, one could probably not have assigned the configuration 2 (which was already known from laborious chemical correlations extending over many years.)... 

Equilibrium vapor pressures were measured in this study by means of a mass spectrometer/target collection apparatus. Analysis of the temperature dependence of the pressure of each intermetallic yielded heats and entropies of sublimation. Combination of these measured values with corresponding parameters for sublimation of elemental Pu enabled calculation of thermodynamic properties of formation of each condensed phase. Previ ly reported results on the subornation of the PuRu phase and the Pu-Pt and Pu-Ru systems are correlated with current research on the PuOs and Pulr compounds. Thermodynamic properties determined for these Pu-intermetallics are compared to analogous parameters of other actinide compounds in order to establish bonding trends and to test theoretical predictions. 

Michael Story is retired from Thermo Electron Corporation. He was involved in the research, design, and commercialization of mass spectrometers for 37 years, and is a cofounder of the Finnigan Corporation. He was a member of previous NRC committees on commercial aviation security (1988-1993) and chaired the Panel on Test Protocol and Performance Criteria. 

RW Niven. Aerodynamic particle size testing using a time-of-flight aerosol beam spectrometer. Pharm Technol 17 72-78, 1993. 

As the anapole interaction is the candidate which directly breaks parity conservation in electromagnetic interaction [1], it is very desirable to test whether the anapole moment could couple to the p decay or not. This experiment can be performed by solid state detectors as well asby a magnetic spectrometer. There are also other choices for the crystal samples [3] and p sources. Since the anapole moment has the same intrinsic structure as for Majorana neutrinos, its coupling is valid to both p decay and p+ decay. 

The equipment list should include all laboratory equipment that is going to cost more than 1,000. This would include special testing devices such as an Instron , an infrared spectrometer, or a chromatograph. 

Luo, S. Andersen, D. Mohr, A. J. Abbreviated Test Report (Part II) for the Chem-ical/Biological Mass Spectrometer (CBMS) Block II Chemical Test. DPG Document No. WDTC-TR-03-081, West Desert Test Center, US Army Dugway Proving Ground, Dugway, UT, 2003. 

In our laboratory, ECD spectra provide important auxiliary data for the proteins and peptides we study. ECD spectra are usually obtained for more dilute samples using strain-free quartz cells having various sample path lengths from 0.2 to 10 mm for concentrations of 0.1-1 mg/ml. To test if concentration effects cause a difference in the interpretation of data from the two techniques, which can be very important for study of unfolded proteins and peptides, we also can use IR cells and samples directly in the ECD spectrometer (Baumruk et al., 1994 Yoder, 1997 Yoder et al., 1997b Silva et al., 2000b). 

Consider ethanol (key sentence coming up). If you were to replace each of the methylene protons in turn with some other group, Z, you would end up with a pair of enantiomers. We call this, the Z test. For this reason, the protons (or whatever groups may be involved, in molecules of the type X-CA2-Y) are described as enantiotopic. This is of no consequence in the spectrometer, because as we have mentioned, enantiomers are not distinguishable by NMR under normal conditions. 

Two methods were used to determine the purity of the final material. The ash content was obtained by calculation of a weight loss of 1 g size graphite sample, after its exposure to 900°C for 4 hours (Superior Graphite AIMS procedure FBQ0001). This test gives a good idea of the total amount of impurities. The nature of impurities and their specific concentrations as measured in ppm or ppb levels, was determined with an ICP inductively coupled plasma spectrometer (Model Jobin Yvon Ultima POXX/681,... 

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