Sample Chamber Research Articles

The ESCAPE system: A combined Raman and time-resolved laser-induced fluorescence instrument to analyze planetary material in a controlled environment

Several sample-return missions such as OSIRIS-REx, Hayabusa2, and Mars 2020 recently have or are currently, collecting the most pristine planetary samples we can analyze on Earth since the Apollo missions. Therefore, it is essential to create instrumentation that will allow preliminary compositional analysis of these materials while preventing oxidation, alteration, or contamination from Earth’s environment. At York University, a small, transportable environmental chamber with temperature, pressure, and atmosphere control has been integrated on an optical table with a combined UV (266 nm) and Green (532 nm) Raman, laser-induced fluorescence, and time-resolved laser-induced fluorescence instrument. This system can collect high-resolution 2D spectroscopic maps, long accumulation point analysis and time-resolved fluorescence ‘fingerprinting’. The sample chamber is capable of pressures <10−4 mbar, temperatures <−20 °C, and different atmospheric compositions such nitrogen, argon, or carbon dioxide via gas hookup. The intended use of the system is to detect and identify minerals and organics within sensitive or fragile planetary samples using minimally destructive laser-based techniques, while maintaining specific environmental conditions to preserve and maintain the pristineness of the material being analyzed, such as samples returned from planetary missions.

Experimental study on the sintering characteristics of biomass ash

The alkaline metal content in biomass is high, which leads to a low initial sintering temperature. Therefore, during the process of direct biomass combustion for power generation, there are serious problems such as ash deposition and slagging on the heating surface, which has become a technical bottleneck for the safe, stable and long-term operation of boilers. In industry, the melting characteristics of ash are commonly used to guide boiler design and operation. However, traditional measurement of ash melting temperature has a large subjective error, and the releasing of alkaline metals during the measurement process results bit higher value, which affects the accuracy of the measured characteristic temperature. Comparingly, the initial sintering temperature is lower than the deformation temperature of the ash. This article provides a device for measuring the sintering temperature of biomass ash by using the pressure drop method. A novel two ash chamber system was invented, in which the alkali element released from the first ash chamber was captured by the downstream second ash chamber to compensate the escaping of alkali element. The initial sintering temperature of the second ash chamber has more accuracy with lower value than that measured by the traditional single sample chamber. XRD was used to analyze the mineral composition and causes of sintering of the ash samples before and after sintering. The results show that the sintering mechanisms of different types of biomass are different. In addition, combined with SEM analysis of rice husk, fruit core, rapeseed straw, and corn straw, the results show that the initial sintering temperature of the ash samples measured by the double chamber measurement method is more accurate than that measured by the single chamber measurement method, further validating the reliability of the two ash column system.

In-situ redox conditions in hydrothermal diamond-anvil cell experiments using various metal gaskets

Hydrothermal diamond-anvil cells (HDACs) have been widely used in various research fields since they were introduced in 1993. Unlike temperature (T) and pressure (P), the redox states of the samples in HDAC experiments were poorly controlled or measured; they were usually estimated by observing the reduction/disappearance of redox-sensitive mineral(s) (e.g., Mo metal) and corresponding formation and growth of such mineral(s) (e.g., MoO2) without in-situ redox measurement. In this study, we demonstrated the generation of H2 during experiments using various metal gaskets, including inert (Re) and chemically more reactive metals (Ni, Co, Mo, and W), in the pure H2O system under various P-T conditions. A technique for quantitative Raman spectroscopic analysis of H2 in HDAC is designed. Based on this technique, the oxygen fugacity (fO2) values of Mo-MoO2 buffer at the experimental P-T conditions were then calculated from these measured H2 pressures. We demonstrated that steady-state redox control can be maintained at a fixed T between 400 and 500 °C in HDAC experiments using a Mo gasket for durations of up to two hours and for those using a Re gasket with an additional Mo rod in the sample between 400 and 800 °C for durations of up to 90 min, regardless of the considerable changes in sample pressure. This demonstration was established by the balance between the rates of H2 generation and H2 loss from the sample chamber. The loss of H2 enhanced the consumption of H2O and therefore reduced the sample pressures during the experiments.We believe that hydrogen contents in every HDAC experiment, which attempt to control the redox state, need in situ measurement, then estimate the real redox state and compare it to thermodynamic equilibrium prediction. To enhance in situ redox control and measurements, modifications of HDAC are required for improving the quantitative Raman spectroscopic analysis technique in both sensitivity and accuracy.

In situ temperature measurement in the pressure chamber of diamond anvil cell

The measurements of temperature directly influence the reasonability of experiments at high pressure and high temperature. In this article, we proposed a new integration design, the built-in thermocouple, for in situ temperature measurements in high-pressure–high-temperature experiments by fusing the characteristics of thermocouples and diamond anvil cells together. By integrating an S-type thermocouple inside the gasket of a diamond anvil cell, we successfully measured the temperature of the sample straight inside the pressure chamber at high pressure and high temperature. The setup underwent multiple experimental tests using internal and external heating techniques, the results of which revealed its capability to directly characterize the temperature of the sample with comparable accuracy and reliability to that of the typical external thermocouple setup. The proposed setup has also resolved the issue of the discrepancy of temperatures inside and outside the sample chamber and enormously expedited the temperature measurements by significantly reducing the response time of the thermocouple. In conclusion, the built-in thermocouple is a promising approach toward high-efficiency, in situ temperature measurements under extreme conditions.

Effects of different fertilization practices on CH4 and N2O emissions in various crop cultivation systems: A case study in Kazakhstan

The present study investigates the effects of different fertilization practices, including chemical and organic fertilizers, on CH4 and N2O emissions in various crop cultivation systems in Kazakhstan. The research focuses on three staple crops: wheat, barley, and corn, which are commonly grown in the region. A randomized complete block design field trial was conducted with three replications for each crop, totaling 27 plots. Gas sampling was carried out five times between June and September 2021, with cylindrical gas sampling chambers inserted into the soil at a depth of 10 cm. The concentrations of CH4 and N2O were analyzed using GS-MS. Results reveal that all three crops exhibited moderate to high CH4 and N2O emissions, with corn consistently displaying the highest emissions. Both chemical and organic fertilizers led to increased emissions of CH4 and N2O compared to control plots. The organic fertilizer treatment occasionally showed slightly higher emissions compared to chemical fertilizer treatment. However, the differences in CH4 and N2O concentrations between fertilized and unfertilized plots were not drastically significant. Notably, environmental factors, such as soil moisture and temperature, played a more prominent role in influencing CH4 and N2O production than the type of fertilizer applied. These findings underscore the significance of optimizing fertilization practices to minimize greenhouse gas emissions while maintaining crop productivity and promoting sustainable agriculture in Kazakhstan.

Dielectric and physico-chemical behavior of single thermally thick wood blocks under microwave assisted pyrolysis

Pyrolysis of thermally thick beech wood blocks with a size of around 2.5 × 8 × 6 cm3 (width × length × height) was carried out in a lab scale microwave reactor with a frequency of 2.45 GHz, operated, both, at 300 W and 600 W under inert conditions, using N2 at around 400 mbar absolute pressure. The microwave cavity had a size of 20 × 20 × 20 cm3. The specific energy supply referred to the untreated wood block was 4–8 W/g, with slight variations depending on the initial water content. The mass loss and the reflected microwave power were in-situ monitored during the experiments. The sample surface and chamber temperatures were measured with a pyrometer and a thermocouple, respectively. Physico-chemical and dielectric properties of the produced solids were investigated and compared to those of chars produced under conventional pyrolysis using the same raw materials. It is shown that the complex dielectric permittivity of the solid products changed drastically during the pyrolysis process, with increasing heating properties as the conversion process evolved. This was easily achieved using 600 W without susceptors. However, 300 W was not enough to achieve a high conversion degree, independently of the irradiation time. This, together with the physico-chemical analyses of the solids, hinted to the importance of the transport kinetics in thermally thick materials, although further investigation is still required.

Low energy electron microscopy at cryogenic temperatures

We describe a cryogenic sample chamber for low energy electron microscopy (LEEM), and present first experimental results. Modifications to our IBM/SPECS aberration-corrected LEEM instrument are presented first. These include incorporation of mechanisms for cooling the sample and its surroundings, and reduction of various sources of heat load. Using both liquid nitrogen and liquid helium, we have reached sample temperatures down to about 15 K. We also present first results for low-temperature LEEM, obtained on a three-monolayer pentacene film. Specifically, we observe a reduction of the electron beam irradiation damage cross-section at 15 eV by more than a factor of five upon cooling from 300 K down to 52 K. We also observe changes in the LEEM-IV spectra of the sample upon cooling, and discuss possible causes.

Revealing the kinetics of non-metallic inclusion reactions in steel using in-situ high temperature environmental scanning electron microscopy

The kinetics of solid-state reactions involving non-metallic inclusions (NMIs) in steel is a topic of growing interest due to the need to understand the effects of heat treatments on NMI composition and stability. In this study, a High Temperature Environmental Scanning Electron Microscope (HT-ESEM) is utilized to conduct in-situ observations of various types of NMIs, including calcium aluminate complex, CaS, MgAl2O4-CaS, MnS, and TiN, in steels at temperatures of 800 °C and 900 °C for different holding times. The observed morphological variations in the NMIs indicate a decrease in the fractions of CaS and MnS, promoting void formation and ferrite–austenite phase transformation. To estimate the NMI reactions with the residual atmosphere in the sample chamber during experiments, HT-ESEM-driven thermodynamic calculations have been performed using FactSage 8.2 software. These calculations provide valuable insights into the interpretation of the experimental data, facilitating a better understanding of the complex NMI reactions in steel.

Evolution of LIBS technology to mobile instrumentation for expediting firearm-related investigations at the laboratory and the crime scene

Gunshot residue (GSR) is one of the few forensic disciplines that lack accurate screening techniques. This study proposes using a mobile LIBS instrument to detect inorganic GSR and compares performance to a previously validated laboratory instrument. The mobile LIBS is designed with advanced configurations specifically for on-site GSR analysis, including a CMOS detector and a sampling chamber that holds up to six typical GSR collection devices with separate gas flow ports to prevent cross-contamination. A significant novelty of the portable instrument is its image magnification, which allows quick searching and visualization of GSR particle morphology. The single-particle imaging and elemental composition capability is one of a kind and offers superior confirmatory features for GSR. The mobile LIBS performance was evaluated for residues collected from the hands of shooters (100 samples) and non-shooters (200 background samples), analyzed sequentially by the mobile instrument and then the laboratory instrument. Accuracies better than 98.8% were obtained by both instruments, demonstrating their suitability for trace IGSR detection from skin specimens. Implementation of this methodology is anticipated to drastically speed up response times (i.e., from several hours per sample by standard SEM-EDS practice to a few minutes by LIBS). The screening methods can be easily incorporated into workflows to improve decision-making processes at the crime scene and laboratory settings, reduce backlogs, and improve case management.

Antigorite Dehydration under Compression and Shear Loadings in a Rotational Diamond Anvil Cell

Mineral dehydration in the subduction zone enormously affects Earth’s geodynamics and the global geochemical cycles of elements. This work uses Raman spectroscopy and X-ray diffraction to investigate the dehydration process of antigorite under compression and shear loading conditions in a rotational diamond anvil cell (RDAC) at room temperature. In order to compare the shear effects, T301 stainless steel and Kapton plastic are applied as the gasket materials. In the experiment using a high-strength T301 stainless steel gasket, two new broad OH-stretching peaks of H2O and H3O2− appear at 3303 and 3558 cm−1, respectively, at 1.7 GPa. The original sharp OH-stretching peaks of antigorite at 3668 and 3699 cm−1 remain, while the central pressure is increased to 8.0 GPa, and the largest pressure gradient is about 2.5 GPa in the sample chamber. In another experiment with a low-strength gasket of Kapton plastic, two new OH-stretching broad peaks of H2O and H3O2− also start to appear at 3303 and 3558 cm−1, respectively, at a lower pressure of 0.3 GPa, but the original sharp OH-stretching peaks of antigorite at 3668 and 3699 cm−1 almost completely vanish as the central pressure reaches 3.0 GPa, with the largest pressure gradient at around 4.8 GPa. The comparison between the two experiments shows that antigorite is easier to dehydrate in the chamber of a Kapton plastic gasket with a larger gradient of shear stress. However, its axial compression stress is lower. The high-pressure Raman spectra of MgO2(OH)4 octahedron and SiO4 tetrahedron in the low wavenumber zones (100–1200 cm−1) combined with the micro-beam X-ray diffraction spectrum of the recovered product strongly support the structural breakdown of antigorite. This investigation reveals that the water-bearing silicate minerals have strong shear dehydration in the cold subduction zone of the plate, which has important applications in predicting the physical and chemical properties of subduction zones and deducing the rate of plate subduction.

Design and realization of a 3-K cryostat for a 10-cm ultrastable silicon cavity

Crystalline optical cavities operating at cryogenic temperatures provide a promising route for realizing the next generation of ultrastable lasers with extremely low thermal noise floor. However, it remains challenging to realize a closed-cycle cryostat for cooling a relatively long cavity to very low temperatures. Here we report on the design and experimental realization of a cryostat operating continuously at 3.1 K for an ultrastable 10-cm silicon cavity. Based on a combination of active temperature control and passive thermal damping, we realize at 3.1 K a two-second temperature instability of 6 × 10−8 K for the cavity. By implementing separate supporting structures for the cryocooler and the sample chamber, we realize vibration control on the 1 × 10−7g level at one second in each spatial direction, where g is the gravitational acceleration. With all these features, our cryostat can support an ultrastable silicon cavity with instability near its fundamental thermal noise floor at averaging time of 1–50 s. With proper upgrading, our platform holds promise for realizing ultrastable lasers with 3 × 10−17 or better frequency stability, which will in turn enable numerous studies on precision metrology and quantum many-body physics.

Water content monitoring in water-in-oil emulsions using a delay line cell

The extraction process of crude oil requires addition of water, resulting in complex emulsions, in which the phases must be separated before the petrochemical processing starts. An ultrasonic cell may be used to determine in real time the water content in water-in-crude oil emulsions. The water content of emulsions can be related to parameters, such as propagation velocity, density and relative attenuation. The ultrasonic measurement cell developed here is composed of two piezoelectric transducers, two rexolite buffer rods, and a sample chamber. It is an inexpensive and robust system. The cell measures the parameters at different temperatures and flow conditions. The tests were performed using emulsions with water volume concentrations from 0% to 40%. The experimental results show that this cell is able to obtain more precise parameters, when compared to similar ultrasonic techniques. The data acquired in real time may be used to improve the emulsion separation, decreasing greenhouse gases and energy requirements.

Multiple electromagnet synergistic control enabled fast and automatic biosensing of Salmonella in a sealed microfluidic chip

Point-of-care testing of pathogens is vital for prevention of food poisoning. Herein, a colorimetric biosensor was elaborately developed to rapidly and automatically detect Salmonella in a sealed microfluidic chip with one central chamber for housing immunomagnetic nanoparticles (IMNPs), bacterial sample and immune manganese dioxide nanoclusters (IMONCs), four functional chambers for housing absorbent pad, deionized water and H2O2-TMB substrate, and four symmetric peripheral chambers for achieving fluidic control. Four electromagnets were placed under peripheral chambers and synergistically controlled to manipulate their respective iron cylinders at the top of these chambers for deforming these chambers, resulting in precise fluidic control with designated flowrate, volume, direction and time. First, the electromagnets were automatically controlled to mix IMNPs, target bacteria and IMONCs, resulting in the formation of IMNP-bacteria-IMONC conjugates. Then, these conjugates were magnetically separated by a central electromagnet and the supernatant was directionally transferred to the absorbent pad. After these conjugates were washed by deionized water, the H2O2-TMB substrate was directionally transferred to resuspend the conjugates and catalyzed by the IMONCs with peroxidase-mimic activity. Finally, the catalysate was directionally transferred back to its initial chamber, and its color was analyzed by the smartphone APP to determinate bacterial concentration. This biosensor could detect Salmonella quantitatively and automatically in 30 min with a low detection limit of 101 CFU/mL. More importantly, the whole bacterial detection procedure from bacterial separation to result analysis was achieved on a sealed microfluidic chip through multiple electromagnet synergistic control, and this biosensor has great potential for point-of-care testing of pathogens without cross contaminations.

Monazite from lithium-bearing pegmatites of the Lipovskoye vein field, Middle Urals (composition and chemical dating)

The relevance of the research is due to the need to improve the method of chemical dating as applied to high-thorium accessory minerals, which are difficult to study by isotope research methods. Purpose of the research is to study the chemical composition of monazite from lithium-bearing granite pegmatites of the Lipovskoye vein field and to determine their age. Research methodology. The quantitative analysis of the chemical composition of monazite was performed on a CAMECA SX 100 electron probe microanalyzer (IGG UB RAS, Ekaterinburg). Measurement conditions: accelerating voltage 15 kV, current strength 250 nA, electron beam diameter 2 μm. The pressure in the sample chamber is 2 ⋅ 10–4 Pa. The spectra were obtained on tilted wave spectrometers, the intensity was measured using analytical lines: Th Ma, U Mb, Pb Ma, Y La, Si Ka, Ca Ka, P Ka, Ce La, La La, Pr Lb, Nd La, Sm Lb, Dy La, Gd Lb. Standard samples: ThO2 , UO2 , Pb2 P2 O7 , diopside, synthetic rare-earth phosphates. The intensity measurement time at the peak for Th is 180 s, U is 100 s, and Pb is 500 s (240 s on one and simultaneously 260 s on another spectrometer), for Y and Si 20 s each, for the other elements 10 s; on the background – two times less. The detection limits for Th, U, and Pb in monazite are 290, 350, and 64 ppm, respectively. The oxygen content was determined under the assumption of the stoichiometry of the composition. Results. It has been established that monazite belongs to the cerium variety and is characterized by high contents of thorium (ThO2 up to 23.6 wt. %) and uranium (UO2 up to 2.5 wt. %). At the same time, cheralite-type isomorphism is realized in phosphate. In a closed Th–U–Pb-system (β = 0.92–0.97), according to the results of chemical dating (according to 20 analyses), monazite-(Ce) shows a weighted average age of 243 ± 7 Ma. When plotting the dependence (ThO2 + UO2 eq) – PbO, the points fall on one isochrone. Calculation of the age from the slope of the isochron gave a dating of 242 ± 17 Ma, MSWD = 0.21, probability = 1.00. Conclusion. It has been established that accessory monazite from lithium-bearing granitic pegmatites of the Lipovskoye vein field (Middle Urals) is of Triassic age. Apparently, this dating shows the time of the secondary transformation of lithium-bearing granitic pegmatites, which are often tectonized, and in some places even boudinaged.

Tungstates of the Boyovskoye tungsten deposit (Southern Urals)

The relevance of the work is due to the need for a mineralogical study of tungsten deposits in the Ural region, which have been mined since the end of the 19th century. The purpose of the work is the diagnostics and detailed description of tungstates from the Boyovskoye tungsten deposit located on the border of the Chelyabinsk and Sverdlovsk regions in the Southern Urals. Analytical studies were carried out in the Laboratory of Physical and Chemical Research Methods of the Institute of Geology and Geochemistry, UB RAS, Ekaterinburg. The chemical composition of minerals was analyzed in polished sections on a CAMECA SX 100 microanalyzer. Measurement conditions: accelerating voltage 15 kV, current 150 nA, electron beam diameter 2 μm. The pressure in the sample chamber is 2 ⋅ 10–4 Pa. The spectra were obtained on tilted wave spectrometers; the intensity was measured from analytical lines. Standard samples: scheelite, wolframite, galena, rutile and chromite. Raman spectra of minerals were obtained using a LabRam HR Evolution spectrometer (Horiba Scientific). A red laser, 532 nm, was used for analysis. As a result of the work, new data on the chemical composition of hubnerite and scheelite were obtained and their Raman spectra were presented. For the first time for the Boyovskoye tungsten deposit, a reliable diagnosis and description of lead tungstate – stolzite was made. The mineral was found in samples with veined quartz in association with muscovite, fluorite, hubnerite and scheelite. It fills cracks and voids in hubnerite, rarely overgrows scheelite or fills cracks in scheelite. It is a later mineral in relation to hubnerite and scheelite. Its chemical composition contains impurities of manganese, calcium, iron and titanium. The stolzite found by us is a mineral of the oxidation zone and, most likely, was formed due to the weathering of wolframite and galena, which is also present in quartz veins.

A novel method for isolation of functional stallion spermatozoa for artificial insemination

In vitro semen purification techniques have been developed that seek to mimic the in vivo selection process, in order to generate the highest possible chance of oocyte fertilization following artificial insemination (Morrell and Rodriguez-Martinez. Vet Med Int. 2011:894767). Since this practice began, there have been many methods developed in an attempt to isolate functional spermatozoa for AI, yet only one method is routinely used – density gradient centrifugation using commercial preparations such as EquiPure. Here, we have developed a novel method of isolating functional spermatozoa and compared sperm quality to spermatozoa isolated with EquiPure. The AI-Port system (Memphasys, Sydney, Australia), comprises a disposable cartridge consisting of a sample chamber – where extended semen is deposited, and a harvest chamber – where isolated spermatozoa is extracted. These chambers are separated by a 5 µm nylon woven membrane, through which highly motile spermatozoa are able to swim from the sample chamber into the harvest chamber over 20 min, leaving behind seminal plasma and other cell types such as leukocytes. Spermatozoa were collected from miniature pony stallions, and immediately extended with EquiPlus semen extender. The ejaculate was split, and spermatozoa were isolated into BWW media with EquiPure (as per manufacturer's instructions; Nidacon, International), or the AI-Port system. Comparisons were conducted between spermatozoa isolated with the AI-Port and EquiPure, which revealed that the yield of AI-Port samples was significantly lower (25.5±5.9%) incomparison to EquiPure samples (44.9±10.2%; Kruskal-Wallis), potentially solvable with prototype improvement. Viability (Eosin-nigrosin) of AI-Port samples was significantly higher than EquiPure samples (94.4±1.1 vs 81.5±2.1%; P≤0.01; ANOVA; respectively). In regard to motility, total motility for AI-Port samples was significantly higher than EquiPure samples (93±1.3 vs 89.5±2.9%; P≤0.05; ANOVA; respectively). Whilst there was no significant difference for progressive motility between AI-Port and EquiPure samples (45.7±3.2 vs 45.6±3.4%; ANOVA; respectively). Both samples were higher than the progressive motility of the initial non-purified ejaculate (30±4.1%; P≤0.05). Mitochondrial superoxide was measured with flow cytometry and MitoSOX red. Likewise, there was no significant difference in superoxide levels between AI-Port and EquiPure samples (10.2±3.1 vs 5.6±0.8%; ANOVA; respectively). However, both samples had a reduced level of superoxide generation compared to the initial non-purified ejaculate (32.5±20.2%; P≤0.05). The DNA integrity was measured with the Halo test, which confirmed AI-Port samples had less DNA damage than EquiPure™ samples (2.0±0.5 vs 10.2±2.1%; ANOVA; P≤0.01; respectively). In summary, the AI-Port effectively isolates high-quality spermatozoa at a comparable or superior level to EquiPure. Its cost-effectiveness and user-friendliness make it a viable option for improving artificial insemination success rates in breeding programs.

An economical setup for atmospheric pressure chemical ionization drift tube ion-mobility mass spectrometry

Ion-mobility (IM) separations—performed in conjunction with mass spectrometry (MS)—increase selectivity of MS analyses. However, IM-MS instruments are costly, and many laboratories are only equipped with standard MS instruments without an IM separation stage. Therefore, it is appealing to upgrade the existing mass spectrometers with low-cost IM separation devices. Such devices can be constructed using widely available materials such as printed-circuit boards (PCBs). We demonstrate coupling of an economical PCB-based IM spectrometer (disclosed previously) with a commercial triple quadrupole (QQQ) mass spectrometer. The presented PCB-IM-QQQ-MS system incorporates an atmospheric pressure chemical ionization (APCI) source, drift tube comprising desolvation and drift regions, ion gates, and transfer line to the mass spectrometer. The ion gating is accomplished with the aid of two floated pulsers. The separated ions are divided into packets, which are sequentially introduced to the mass spectrometer. Volatile organic compounds (VOCs) are transferred with the aid of nitrogen gas flow from the sample chamber to the APCI source. The operation of the system has been demonstrated using standard compounds. The limits of detection for 2,4-lutidine, (−)-nicotine, and pyridine are 2.02 × 10−7 M, 1.54 × 10−9 mol, and 4.79 × 10−10 mol, respectively. The system was also used to monitor VOCs emitted from the porcine skin after exposure to nicotine patches, and VOCs released from meat undergoing the spoilage process. We believe this simple APCI-PCB-IM-QQQ-MS platform can be reproduced by others to augment the capabilities of the existing MS instrumentation.

30 Reference Materials for the Measurement of Metals in Workplace Air

Abstract For the production of filters coated with metal oxides an aqueous metal salt solution is injected into a hydrogen/oxygen flame of a particle generator leading to the pyrolysis of the metal salts into nano-scaled metal oxide dust. The particles are introduced into a large sampling chamber (20 m³) via a dust tunnel (20 m). So far, the system was tested for Zn, Cu, Pb, Co, Ni, Mn and In but it should be suitable with all metals obtainable as soluble metal salts. For sample generation an eight-fold sampling system was developed for the GSP sampler. The constancy of the flow rate is assured by critical orifices. Up to fourteen of these systems can be operated to produce 112 samples in parallel. Nevertheless, for the production of a reference material a significantly higher number of samples will be needed. To achieve this aim the environmental conditions of the dust generation have to be stabilized for consecutive runs. The major problem was the temperature rise of the dust channel during the particle generation due to the heat of the flame. An additional heater was installed to work at a constant temperature of 30 °C. Three consecutive filter series were manufactured. The achieved temperature constancy of 30± 0.5 °C makes it possible to combine the successive filter series. The loadings of the combined series were Cobalt: 3.25±0.058 µg/filter, Nickel: 13.78±0.23 µg/filter, Lead: 109.5±3.0, Copper: 9.65 ±0.18 µg/filter and Zinc: 32.66±0.72 µg/filter.

Oil contamination of sediments by freeze-drying versus air-drying for organic geochemical analysis

Freeze-drying is widely used in geochemical laboratories for preparing wet solid environmental samples such as sediments and soils before being analyzed for their contents and states of various metal elements and labile organic components that may be temperature- and/or redox-sensitive. Screening bulk geochemical analysis of two Artic lake sediment samples prepared by freeze-drying displayed unexpectedly high contents of labile organic matter (OM) represented by the Rock–Eval S1 peaks (e.g., 8.12 and 4.84 mg HC/g sediment). The amount of labile OM was reduced greatly for the freeze-dried sediment samples after a thorough cleaning of the freeze-drier sample chamber (e.g., 2.75 and 1.46 mg HC/g sediment), but was still significantly higher than that of the equivalent air-dried samples (e.g., 0.76 and 0.23 mg HC/g sediment). Compositional analysis of the labile OM fractions by gas chromatography (GC) of both freeze-dried and air-dried aliquots of the same sediments indicates the presence of unresolved complex mixture (UCM) humps of C10–C23 hydrocarbons in the freeze-dried samples. In contrast, air-dried samples, either real sediments or blank laboratory materials represented by clean sand and thermally spent shale, do not show the C10–C23 hydrocarbon UCM humps on their GC traces. The hydrocarbon UCM humps persist in the freeze-dried samples even they further went through air-drying at ambient conditions. Both bulk and compositional analytical results in this work appear to indicate the potential risk of introduction of external hydrocarbons to the prepared materials during freeze-drying process, especially if an aged freeze-drier was used without being thoroughly cleaned and if pump oil and cooling fluids were components of the device.

Sampling chamber with minimal wall surface for simultaneous emission testing of diisocyanates and diamines from polyurethane products

A sampling chamber was developed for emission testing of diisocyanates, methylene diphenyl diisocyanate (MDI), toluene diisocyanate (TDI), and corresponding diamines, methylene diphenyl diamine (MDA), and toluene diamine (TDA) from polyurethane (PU) product surfaces. In addition, a methodology for validation of the sampling chamber was presented, based on the introduction of generated standard atmospheres of the different diisocyanates and diamines to the sampling chamber system. Sampling of diisocyanates and diamines was performed on a circular glass fiber filter (150mm diameter) impregnated with dihexyl amine (DHA) and acetic acid (AA) positioned inside a cylindrical stainless steel sampling chamber. The diisocyanates were immediately derivatized to DHA derivatives, and the amines were derivatized in a subsequent work-up procedure with ethyl chloroformate (ECF). The design of the sampling chamber and the presented methodology allowed for simultaneous sampling and analysis of diisocyanates and diamines of emission from a large surface area with minimal interior wall interaction in the sampling chamber. Performance characteristics of the sampling chamber for different sampling times and air humidity were obtained by determining collected amounts of the diisocyanates and diamines in the different parts of the sampling chamber. The repeatability of the collected amount on the impregnated filters in the sampling chamber was 15% with an overall recovery for 8h of sampling in the range of 61% to 96%. The performance of the sampling chamber was not affected by air humidity (5%-75% RH), and no breakthrough during sampling was observed. LC-MS/MS determinations allowed for emission testing of diisocyanates and diamines on product surfaces as low as 10-30ng m-2 h-1.