Quantitative determination of chelators and their degradation products in mixed hazardous wastes from Tank 241-SY-101 using derivatization GC/MS

Considerable attention has been focused on chelators such as ethylenediaminetetraacetic acid (EDTA) and N-(2-hydroxyethyl)ethylenediaminetriacetic acid (HEDTA), which form water-soluble complexes with most heavy metals. Most radionuclides are included in this class of constituents. As a result, chelator complexes have become very important environmentally because of their tendency to enhance the mobility of heavy metals through the soil and potentially contaminate groundwater. In addition, there is a correlation between chelator concentration and crust formation/gas release. The chelators are a class of compounds whose low volatility and high polarity preclude analysis by gas chromatography/mass spectrometry (GC/MS) without prior derivatization. Waste samples from a double-shell storage tank at Hanford were derivatized with BF₃/methanol and analyzed using GC/MS. Results indicate the presence of EDTA, HEDTA, nitrilotriacetic (NTA), and citric acid. Nitrosoiminodiacetic acid was identified and determined to be an artifact of the derivatization procedure; it is assumed to arise from nitrosation of iminodiacetic acid in the waste sample.     

Regioselective synthesis of antiparallel loops on a macrocyclic scaffold constrained by oxazoles and thiazoles

The regioselective syntheses and structures are reported for two tris-macrocylic compounds, each possessing two antiparallel loops on a macrocyclic scaffold constrained by two oxazoles and two thiazoles. NMR solution structures show the loops projecting from the same face of the macrocycle. Such molecules are shown to be prototypes for mimicking multiple loops of proteins.[structure: see text]     

Two-dimensional synthetic aperture imaging in the optical domain

In scan-mode synthetic aperture imaging radar, spatial resolution in a range is given by a frequency-swept waveform, whereas resolution in the orthogonal direction is derived from the record of phase as the beam footprint executes linear motion over the object. We demonstrate here what is to our knowledge the first two-dimensional imaging that uses exactly this process in the optical domain for a 1 cm x 1 cm object with 90 mumx170 mum resolution.     

Autoradiographische Untersuchungen zur Vermisechung von Baustoffkomponenten

Die Feinverteilung des Kalkes im Kalk-Quarzsand-Gemisch ist eine notwendige Bedingung fur hohe erreichbare Festigkeit der Silikatbaustoffe. Vergleiehende Untersuchungen über die Kalkverteilung an neutronenaktivierten feinkörnigen Baustoffproben mit Hilfe von Szintillationsmessungen des ⁴⁷Ca-Gehaltes und mittels autoradiographischer Darstellung der Kalkverteilung in kleinen Prüfkörpern unter Ausnützung der relativ weichen β-Strahlung des ⁴⁵Ca ergaben, daβ die autoradiographischen Aussagen über die Homogenität der Proben am besten mit den Festigkeitsiwerten der Prüfkörper korrespondieren.     

Organic analysis of the headspace of hanford waste tank 241-C-103

Organic species from the headspace of one Hanford radioactive waste tank are described. Samples were collected either using a sorbent trap or a SUMMA^TM canister and were analyzed by gas chromatograph and mass spectrometry. The headspace contained several organic components, including alkanes, alkenes, ketones, aldehydes, organic nitriles, and chlorinated hydrocarbons. Sorbent trap samples were designed to collect only normal paraffin hydrocarbons (NPHs). A comparison of NPH data from sorbent traps and SUMMA^TM cans revealed results of 693 and 1320 mg/m³, NPH respectively. Significant differences were observed in NPH values when samples were collected at different times, or at different locations in the tank. These data suggest either the time of collection, or the position of the sampling device are important variables in the analysis of organic species from Hanford tanks.     

Rapid separation of beryllium and lanthanide derivatives by capillary gas chromatography

Previous studies describe derivatization of metal ions followed by analysis using gas chromatography, usually on packed columns. In many of these studies, stable and volatile derivatives were formed using fluorinated β‐diketonate reagents. This paper extends previous work by investigating separations of the derivatives on small‐diameter capillary gas chromatography columns and exploring on‐fiber, solid‐phase microextraction derivatization techniques for beryllium. The β‐diketonate used for these studies was 1,1,1,2,2,6,6,7,7,7‐decafluoro‐3,5‐heptanedione. Derivatization of lanthanides also required addition of a neutral donor, dibutyl sulfoxide, in addition to 1,1,1,2,2,6,6,7,7,7‐decafluoro‐3,5‐heptanedione. Unoptimized separations on a 100‐μm i.d. capillary column proved capable of rapid separations (within 15 min) of lanthanide derivatives that are adjacent to one another in the periodic table. Full‐scan mass spectra were obtained from derivatives containing 5 ng of each lanthanide. Studies also developed a simple on‐fiber solid‐phase microextraction derivatization of beryllium. Beryllium could be analyzed in the presence of other alkali earth elements (Ba(II) and Sr(II)) without interference. Extension of the general approach was demonstrated for several additional elements (i.e. Cu(II), Cr(III), and Ga(III)).     

Qualitative determination of low-molecular-weight organic acids in mixed hazardous wastes using thermospray liquid chromatography/mass spectrometry

A technique has been developed for the qualitative determination of low-molecular-weight organic acids in radioactive, mixed hazardous wastes using thermospray liquid chromatography/mass spectrometry. A tank waste was analyzed, and the results indicated the presence of citric, glycolic, acetic, and nitrosoiminodiacetic acid (NIDA). Further investigation revealed NIDA was formed under acidic conditions with the reaction of iminodiacetic acid and the high nitrate/nitrite concentration present in the waste.