Radon and CO2 tracer for radioxenon subsurface sampling in the On Site Inspection

<p>The detection of anomalous concentration of Xenon radiosotopes in the subsurface gases during an On Site Inspection (OSI) is a strong indicator of a suspicious underground nuclear explosion. This implies that the sampling methodology ensure the collection of a reliable representative subsurface gaseous sample, avoiding the mixing with atmospheric gases. Radioxenon sampling in shallow layers can provide reliable results for desert areas, but different local geological features could result in more complex migration of subsurface gases to the very near superficial layers affecting the representativeness of the sample.</p><p>Radon is currently use as tracer to reveal the effective sampling of gases form the deep surface, so its measurement is coupled with the collection of radioxenon subsurface gases. The detection of radon anomalous concentration in subsurface gases could indicate different causes: high Radon content in subsurface indicate high radon concentration underground caused by the accumulation in an underground and confined cavity; on the other side, low radon detection in subsurface indicate low radon concentration underground that can be indicative of the absence of an underground cavity or the presence of rocks in the cavity absorbing radon. This lead to the consideration that radon is not a univocal tracer for Xe surface sampling in the OSI. A portable isotopic analyzer (that measures d13C and CO2) could be used to localize the faults and fracturing that could lead to a seeping of the subsurface gases. Therefore, this technique could be proposed as an auxiliary equipment for a preliminary activity during an OSI and a monitoring tool during subsurface gas sampling.</p>

Evaluation of Orchid-Like Aroma Between Different Grades of Taiping Houkui Tea by Solid-Phase Microextraction and Comprehensive Two-Dimensional Gas Chromatography Coupled with Time-of-Fight Mass Spectrometry

Background: Taiping houkui tea won the title of “the King of Green Tea” at the International Tea Exposition in 2004, which had an orchid fragrance but the material basis of the orchid fragrance had not been revealed yet. Objective: To investigate the material basis of the orchid fragrance and identify the quality grade of Taiping houkui tea. Methods: A method was developed for evaluating orchid-like aroma between different grades Taiping houkui tea by solid-phase micro extraction (SPME) and comprehensive two-dimensional gas chromatography coupled with time-of-fight mass spectrometry (GC×GC-TOFMS). The crushed tea sample in a 25 mL headspace bottle was incubated at 90°C for 10 min. Then the gaseous sample was extracted by SPME divinylbenzene/polydimethylsiloxane fiber for 50 min and thermally desorpted at 250°C for 2 min. Results: In total, 735 volatile compounds were determined by SPME- GC×GC-TOFMS and 15 compounds were related to orchid-like aroma. Conclusions: The high-quality Taiping houkui tea has the orchid fragrance and the low-grade one does not; thus orchid-like aroma can be used as a reference of grades of Taiping houkui tea. Highlights: Thirty different grades of Taiping houkui tea samples were compared and analyzed experimentally, and the results showed that the special aroma substances, which played a key role in grade discrimination of Taiping houkui tea, were found by the statistical method.

UV photochemical vapor generation–nitrogen microwave induced plasma optical emission spectrometric determination of nickel

Photochemical vapor generation was utilized for gaseous sample introduction into a nitrogen microwave induced plasma optical emission spectrometer in order to enhance the analytical performance.

The high-resolution absorption spectroscopy branch on the VUV beamline DESIRS at SOLEIL

A VUV absorption spectroscopy facility designed for ultra-high spectral resolution is in operation as a dedicated branch on the DESIRS beamline at Synchrotron SOLEIL. This branch includes a unique VUV Fourier transform spectrometer (FTS) and a dedicated versatile gas sample chamber. The FTS instrument can cover a large UV–VUV spectral range from 4 to 30 eV, with an ultimate line width of 0.08 cm−1on a large spectral window, ΔE/E= 7%, over which all spectral features can be acquired in a multiplex way. The performance can be considered to be a middle ground between broadband moderate-resolution spectrometers based on gratings and ultra-high-spectral-resolution VUV tunable-laser-based techniques over very narrow spectral windows. The various available gaseous-sample-handling setups, which function over a wide range of pressures and temperatures, and the acquisition methodology are described. A selection of experimental results illustrates the performance and limitations of the FTS-based facility.