共查询到20条相似文献,搜索用时 31 毫秒
1.
S. Biegalski O. A. Ezekoye M. Pickering J. M. Peña S. Waye 《Journal of Radioanalytical and Nuclear Chemistry》2008,276(2):441-445
Studies show that aerosols with natural activity have an aerodynamic diameter in the range of 0.1 to 1 μm. In contrast, nuclear
explosions generally produce radioactive aerosols with aerodynamic diameters less than 0.1 μm and greater than 1 μm. These
differences in aerosol sizes are quite fortuitous because they allow aerosol aerodynamic diameter to be utilized as a physical
property to separate aerosols of natural origin from those produced in a nuclear explosion. Data collected in Austin, TX and
at U.S. CTBT IMS radionuclide stations have been utilized to forecast detection limit improvements possible given an aerosol
size separation capability. 相似文献
2.
Young Hyun Cho Wanno Lee Kun Ho Chung Geun Sik Choi Chang Woo Lee 《Journal of Radioanalytical and Nuclear Chemistry》2007,274(3):531-538
The seasonal variation of the 7Be activities in air and the size distribution of the 7Be aerosols were studied by using a continuous air sampler and a five stage cascade impactor. The mean monthly activity level
of 7Be at the Korea Atomic Energy Research Institute (KAERI) site varied from 0.5 to 4.8 Bq·m−3 and revealed a seasonal variation, in which the 7Be activity levels were high in winter and low in summer. The mass size distribution showed a bi-modal distribution with a
higher peak around 0.49 μm and a smaller peak between 3 μm and 7.2 μm. The activity median aerodynamic diameter (AMAD) decreased
with increasing ambient 7Be concentrations. The mean residence times by using a mean growth rate of 0.004 μm·h−1 were estimated to be 2.5–6.4 days. The AMAD has an increasing tendency with higher relative humidity. It seemed that the
high humidity condition facilitated the growth of the aerosol, resulting in increased deposition rates of the aerosols and
the low 7Be content in the surface air. The AMAD of the 7Be aerosols increased with an increasing temperature, but the temperature dependency of AMAD should be explained with geological
and meteorological conditions. 相似文献
3.
B. Berlinger N. Benker S. Weinbruch B. L`Vov M. Ebert W. Koch D. G. Ellingsen Y. Thomassen 《Analytical and bioanalytical chemistry》2011,399(5):1773-1780
Physicochemical properties important in exposure characterisation of four different welding aerosols were investigated. Particle
number size distributions were determined by scanning mobility particle sizer (SMPS), mass size distributions by separation
and weighing the individual size fractions of an 11-stage cascade impactor. The size distribution of the primary particles
of agglomerates, chemical composition and morphology of the particles were examined by TEM. There were significant differences
in the particle number size distributions of the different welding aerosols according to the SMPS determinations. The particle
mass size distributions determined gravimetrically were, however, not really different. The dominant range with respect to
mass was between 0.1 and 1 μm, regardless of the welding technique. Most of the primary particles in all different welding
aerosols had diameters between 5 and 40 nm. All types of primary particles had a tendency to form chainlike agglomerates.
A clear size dependence of the particle chemical composition was encountered in the case of manual metal arc welding aerosol.
Small particles with diameters below 50 nm were mostly metal oxides in contrast to larger particles which also contained more
volatile elements (e.g. potassium, fluorine, sodium, sulphur). 相似文献
4.
Jinze Li Wenjing Xie Lu-Tao Weng Chak K. Chan Chi-Ming Chan 《Surface and interface analysis : SIA》2020,52(5):264-271
Size-fractionated aerosol particles were collected with a MOUDI 10-stage cascade impactor from an urban roadside place in a downtown area of Hong Kong. Fine aerosol particulate samples from stage 6 (aerodynamic particle diameter between 0.56 and 1 μm) and stage 9 (aerodynamic particle diameter between 0.10 and 0.18 μm) were pretreated at a chosen temperature, including −100°C, −50°C, 25°C, and 60°C, in a load lock chamber and then analyzed using time-of-flight secondary ion mass spectrometry (ToF-SIMS) at the same temperature (−100°C). Principal component analysis (PCA) was applied to further analyze ToF-SIMS spectra of aerosol particles with different pretreatment temperatures from two selected stages. ToF-SIMS results showed that the intensities of aliphatic hydrocarbon ions such as C4H7+ and C4H9+ and amine ions such as C2H8N+ and C4H12N+ decreased with an increase of the pretreatment temperature under ultrahigh vacuum conditions. We have shown that analyses of this type of aerosol particles using ToF-SIMS should not be conducted at ambient temperature but at low temperature (eg, −50°C). In addition, we also developed a procedure that can be used to analyze aerosol particle samples under ultrahigh vacuum environment. 相似文献
5.
Su-Ching Kuo 《Analytica chimica acta》2009,653(1):91-96
The purpose of this study was to develop and test a diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) method, a fast and non-destructive method without extraction, and compare it with the standard gas chromatography (GC) method currently used. A micro-orifice uniform deposit impactor (MOUDI) was used to sample all the size distributions of the aerosol particles of essential oils to investigate the relation between size distributions and the indoor concentration distributions of ylang essential oils. Correlation coefficients for DRIFTS and GC were 0.9904, 0.9910, 0.9913, and 0.9983 for eugenol, isoeugenol, methyl ether, and eugenyl acetate, respectively. The results showed that the concentrations of the four eugenol derivatives of smoke were approximately three times higher than those of mist. Additionally, the major size distributions of aerosol were 0.19 μm and 1.8 μm for the smoke and mist methods, respectively. Because these two methods produce similar results, DRIFTS is a practical method for assessing these fragrances in aerosols. 相似文献
6.
Oster M Elsasser M Schnelle-Kreis J Zimmermann R 《Analytical and bioanalytical chemistry》2011,401(10):3173-3182
The on-line analysis of single aerosol particles with mass spectrometrical methods is an important tool for the investigation
of aerosols. Often, a single laser pulse is used for one-step laser desorption/ionisation of aerosol particles. Resulting
ions are detected with time-of-flight mass spectrometry. With this method, the detection of inorganic compounds is possible.
The detection of more fragile organic compounds and carbon clusters can be accomplished by separating the desorption and the
ionisation in two steps, e.g. by using two laser pulses. A further method is, using a heated metal surface for thermal desorption
of aerosol particles. If an ultraviolet laser is used for ionisation, a selective ionisation of polycyclic aromatic hydrocarbons
(PAH) and alkylated PAH is possible via a resonance-enhanced multiphoton-ionisation process. Laser velocimetry allows individual
laser triggering for single particles and additionally delivers information on aerodynamic particle diameters. It was shown
that particles deriving from different combustion sources can be differentiated according to their PAH patterns. For example,
retene, a C4-alkylated phenanthrene derivative, is a marker for the combustion of coniferous wood. In this paper, the first field application
of a thermal desorption resonance-enhanced multiphoton-ionisation single particle time-of-flight mass spectrometer during
a measurement campaign in Augsburg, Germany in winter 2010 is presented. Larger PAH-containing particles (i.e. with aerodynamic
diameters larger than 1 μm), which are suspected to be originated by re-suspension processes of agglomerated material, were
in the focus of the investigation. Due to the low concentration of these particles, an on-line virtual impactor enrichment
system was used. The detection of particle-bound PAH in ambient particles in this larger size region was possible and in addition,
retene could be detected on several particles, which allows to identify wood combustion as generic source of these particles.
The observed diurnal distribution of these larger particles, however, support the origin by traffic induced re-suspension
of sedimented/agglomerated material. 相似文献
7.
Development and certification of the new NIES CRM 28: urban aerosols for the determination of multielements 总被引:1,自引:0,他引:1
Mori I Sun Z Ukachi M Nagano K McLeod CW Cox AG Nishikawa M 《Analytical and bioanalytical chemistry》2008,391(6):1997-2003
A new environmental certified reference material (CRM) for the determination of multielements in aerosol particulate matter
has been developed and certified by the National Institute for Environmental Studies (NIES), Japan, based on analyses by a
network of laboratories using a wide range of methods. The origin of the material was atmospheric particulate matter collected
on filters in a central ventilating system in a building in Beijing city centre. The homogeneity and stability of this material
were sufficient for its use as a reference material. Values for elemental mass fractions in the material were statistically
determined based on the analytical results of the participating laboratories. Eighteen certified values and 14 reference values
were obtained. The diameters, obtained from a micrographic image using image analysis software, of 99% of the particles were
less than 10 μm, demonstrating that almost all the particles in the material could be classified as particles of 10 μm or
less in aerodynamic diameter. The chemical composition and particle size distribution of this material were close to those
of an authentic aerosol collected in Beijing. NIES CRM 28 is appropriate for use in analytical quality control and in the
evaluation of methods used in the analysis of aerosols, particularly those collected in urban environments in northeast Asia
Figure New NIES CRM 28 Urban Aerosols and photo micrograph of the material 相似文献
8.
J. M. Ondov F. Divita Jr. A. Suarez 《Journal of Radioanalytical and Nuclear Chemistry》1995,192(2):215-228
Aerosol particles smaller than 1.8 m were size-fractionated with micro-orifice impactors at two urban sites near Washington, DC, and analyzed for 44 elements including, As, Se, Sb, and Zn, i.e., elements strongly associated with coal combustion, incineration, and regionally transported secondary aerosol, by Instrumental Neutron Activation. Size distribution parameters were determined nonparametrically and with a least-squares peak-fitting method using impactor calibration data. Geometric and fitted mass mean aerodynamic diameters typically differed by <10% and increased continuously with increasing relative humidity (RH) in the range 56 to 79%, but along different curves for samples influenced by local and distant sources. The geometric mass mean diameters for samples influenced by winds from the direction of local sources were uniformly smaller than those influenced by westerly winds bearing aerosol from distant, regional, sources. At 60% RH, gmmads were As, 0.30±0.03 and 0.46±0.04; Se, 0.33±0.06 and 0.54±0.04; Sb, 0.39±0.03 and 0.53±0.04; and Zn, 0.39±0.06 and 0.53±0.08; respectively. 相似文献
9.
Alexandre Albinet Nicolas Papaiconomou Julien Estager Joël Suptil Jean-Luc Besombes 《Analytical and bioanalytical chemistry》2010,396(2):857-864
A new ionic liquid 1-octyl-3,5-dimethylpyridinium iodide ([O35LUT]+[I]−) was synthesized and utilized as coating for an ozone denuder device based on a high-volume aerosol sampler (30 m3 h−1). Particle transmission of the denuder was studied, and over 99% of particles ranging from 10 to 2,500 nm were transmitted.
The device, containing 4.66 g of ionic liquid, was used outdoors, under dry and damp atmospheric conditions. In order to expose
the device to an average concentration of 120 ppbv (240 μg m−3) of ozone in air, an additional production of ozone was directly injected into the denuder. Under these conditions, over
97% of ozone was removed for approximately 120 h (5 days). Therefore, iodide-based ionic liquids can be used as a new alternative
to conventional denuder coatings in order to reduce artifacts occurring during sampling of particulate matter. Future applications
are not limited to ozone removal for specific aerosol sampling methods. 相似文献
10.
Chutima Kranrod Supitcha Chanyotha Nares Chankow Shinji Tokonami Tetsuo Ishikawa 《Journal of Radioanalytical and Nuclear Chemistry》2013,296(2):625-630
A new portable type cascade impactor has been developed to determine the activity size distribution of radon and thoron progeny in a natural environment more efficiently. The modified impactor consists of 4 stages with a back up filter stage for the collection of aerosol samples. The aerosol cut points in the impactor are set for 10, 2.5, 1 and 0.5 μm at a flow rate of 4 L min?1. Five CR-39 chips were used as alpha detectors for each stage. In order to separate α particles emitted from radon and thoron progeny, CR-39 detectors are covered with aluminum-vaporized Mylar films. The thickness of each film is adjusted to allow α particles emitted from radon and thoron progeny to reach the CR-39 detectors. The technique has been successfully tested in field studies, particularly inside a mineral treatment industry in Thailand to estimate doses in the working environment. The dose calculations by lung dose evaluation program showed that activity median aerodynamic diameters played a significant role in determining the particle size distributions of the attached radon and thoron progeny. The dose conversion factor determined from short term measurements due to exposure from the inhalation of thoron and its progeny was found to be 4 times higher than comparable values for radon and its progeny. The effective dose for workers exposed to radon is about 4–6 times higher than thoron. 相似文献
11.
Mohammed A. Abounassif Mohammed M. Hefnawy Gamal A. E. Mostafa 《Monatshefte für Chemie / Chemical Monthly》2012,73(Z1):365-371
Abstract
A stereoselective HPLC method has been developed for the simultaneous determination of oxprenolol enantiomers in urine and pharmaceutical products. Enantiomeric resolution of oxprenolol was achieved on cellulose tris(3,5-dichlorophenylcarbamate) immobilized onto a 5 μm spherical porous silica chiral stationary phase (CSP) known as Chiralpak IC with UV detection at 273 nm. The mobile phase consisted of n-hexane:isopropanol:triethylamine 70:30:0.1 (v/v/v) at a flow rate of 1.0 cm3/min. The method was validated for its linearity, accuracy, precision, and robustness. The calibration curves were linear over the range of 0.5–75 μg/cm3, with a detection limit of 0.1 μg/cm3 for each enantiomer. An average recovery of 99.0% and a mean relative standard deviation of 2.6% at 40.0 μg/cm3 for S-(−)- and R-(+)-enantiomers were obtained. The overall recoveries of oxprenolol enantiomers from pharmaceutical formulations were in the range 97.5–99.0%, with RSDs ranging from 0.6 to 0.8%. The mean extraction efficiency of oxprenolol from urine was in the range of 86.0–93.0% at 0.5–5 μg/cm3 for each enantiomer. The assay method proved to be suitable as a chiral quality control for oxprenolol formulations using HPLC and for therapeutic drug monitoring. 相似文献12.
Size-fractionated aerosol samples collected with micro-orifice impactors at Camden, NJ, a heavily industrialized urban area, and at two sites near Washington, DC, were analyzed for elemental constituents determined instrumentally from short-lived neutron activation products. A least-squares peak-fitting method was used with impactor calibration data to determine log-normal distribution parameters, i.e., mass median aerodynamic diameter (MMAD) and geometric standard deviation (g) for particles bearing S, V, Br, and I. For these elements, MMADs ranged from 0.24 to 0.65 m; 0.23 to 0.53 m; 0.22 to 0.61 m, and 0.20 to 0.48 m, respectively. 相似文献
13.
Atmospheric particles were sampled and fractionated according to their size by a cascade impactor in Berlin, capital city of Germany, on the Brocken, peak of the Harz mountains and on the Szrenica peak in the Giant mountains, Republic Poland. The fractionated particles were collected on small graphite targets and subsequently analyzed by ETV-ICP-MS. Distribution curves were measured showing trace-metal contents in air versus the aerodynamic particle diameter for the elements Pb, Ag, Cd and Tl. Despite good element correlation, the distribution curves differ significantly for the three sampling locations. The limits of detection for the elements of concern were in the pg/m3 range at a sampling time of 4 h. An attempt was made to determine single particles: in urban aerosols a content was found of 1 · 10–13 g Tl and 9 · 10–13 g Ag in single particles of the size fraction < 7.5 μm and > 3.45 μm. 相似文献
14.
The capabilities of total-reflection X-ray fluorescence (TXRF) analysis were investigated to develop an efficient, simple, rapid and low cost analytical method for aerosols. The technique involves direct impaction of airborne particulate matter on the quartz sample-reflector discs for TXRF. Special attention was paid to bounce-off effects, and hence the aerosol size distributions for the impactor stages; influence of siliconizing the quartz discs on the adhesion of particles; choice of the internal standard; local distribution of the material deposited on the quartz disc; and alternative materials for aerosol collection. Moreover, the proposed method could be used in combination with a one-stage impactor for total aerosol mass collection and analysis. 相似文献
15.
Urchin-like ZnO structures assembled with nanorods have been synthesized by cetyltrimethylammonium bromide-assisted hydrothermal
method. The as-obtained products were characterized by powder X-ray diffraction, field-emission scanning electron microscopy
for the study of crystal structure and morphology. The ZnO urchin is constructed of well-assembled nanorods of length ~3 μm
range and diameter ~20 nm. Micro-Raman study shows characteristic Raman-active mode of hexagonal ZnO at 439 cm−1 and also mode related to defects at ~581 cm−1. The ZnO urchin assembled with nanorods possessed band edge emission at 3.085 eV and defect related visible emission at 2.97,
2.57, and 2.36 eV. 相似文献
16.
U.E.A. Fittschen F. Meirer C. Streli P. Wobrauschek J. Thiele G. Falkenberg G. Pepponi 《Spectrochimica Acta Part B: Atomic Spectroscopy》2008
In this study a new procedure using Synchrotron total reflection X-ray fluorescence (SR-TXRF) to characterize elemental amounts in atmospheric aerosols down to particle sizes of 0.015 um is presented. The procedure was thoroughly evaluated regarding bounce off effects and blank values. Additionally the potential of total reflection X-ray fluorescence–X-ray absorption near edge structure (SR-TXRF-XANES) for speciation of FeII/III down to amounts of 34 pg in aerosols which were collected for 1 h is shown. The aerosols were collected in the city of Hamburg with a low pressure Berner impactor on Si carriers covered with silicone over time periods of 60 and 20 min each. The particles were collected in four and ten size fractions of 10.0–8.0 μm, 8.0–2.0 μm, 2.0–0.13 μm 0.13–0.015 μm (aerodynamic particle size) and 15–30 nm, 30–60 nm, 60–130 nm, 130–250 nm, 250–500 nm, 0.5–1 μm, 1–2 μm, 2–4 μm, 4–8 μm, 8–16 μm. Prior to the sampling “bounce off” effects on Silicone and Vaseline coated Si carriers were studied with total reflection X-ray fluorescence. According to the results silicone coated carriers were chosen for the analysis. Additionally, blank levels originating from the sampling device and the calibration procedure were studied. Blank levels of Fe corresponded to 1–10% of Fe in the aerosol samples. Blank levels stemming from the internal standard were found to be negligible. 相似文献
17.
B. S. Gilfedder R. Chance U. Dettmann S. C. Lai A. R. Baker 《Analytical and bioanalytical chemistry》2010,398(1):519-526
Iodine has recently been of interest in atmospheric chemistry due to its role in tropospheric ozone depletion, modification
of the HO/HO2 ratio and aerosol nucleation. Gas-phase iodine chemistry is tightly coupled to the aerosol phase through heterogeneous reactions,
which are dependent on iodine concentrations and speciation in the aerosol. To date, the only method available for total iodine
determination in aerosols is collection on filters by impaction and quantification by neutron activation analysis (NAA). NAA
is not widely available to all working groups and is costly to commission. Here, we present a method to determine total iodine
concentrations in aerosol impact filter samples by combustion of filter sub-samples (∼5 cm2) at 1,000 °C, trapping in deionised water and quantification by UV/Vis spectroscopy. Both quartz and cellulose filters were
analysed from four separate sampling campaigns. The method proved to be sensitive (3σ = 6 ng absolute iodine ≈ 3 pmol m−3) precise (RSD ∼ 5%) and accurate, as determined by external and standard addition calibrations. Total iodine concentrations
ranged from 10 pmol m−3 over the Southern Ocean to 100 pmol m−3 over the tropical Atlantic, in agreement with previous estimates. The soluble iodine concentration (extracted with water
and measured by ICP-MS) was then subtracted from the total iodine to yield non-water-soluble iodine (NSI). The NSI fraction
ranged from 20% to 53% of total iodine, and thus can be significant in some cases. 相似文献
18.
S. Chowta P. K. Mohapatra S. C. Tripathi B. S. Tomar V. K. Manchanda 《Journal of Radioanalytical and Nuclear Chemistry》2010,285(2):309-314
Radiochemical results of U isotopes (234U, 235U and 238U) and their activity ratios are reported for well waters as local sources of drinking waters collected from the ten settlements
around the Semipalatinsk Nuclear Test Site (SNTS), Kazakhstan. The results show that 238U varies widely from 3.6 to 356 mBq/L (0.3–28.7 μg/L), with a factor of about 100. The 238U concentrations in some water samples from Dolon, Tailan, Sarzhal and Karaul settlements are comparable to or higher than
the World Health Organization’s restrictive proposed guideline of 15 μg (U)/L. The 234U/238U activity ratios in the measured water samples are higher than 1, and vary between 1.1 and 7.9, being mostly from 1.5 to
3. The measured 235U/238U activity ratios are around 0.046, indicating that U in these well waters is of natural origin. It is probable that the elevated
concentration of 238U found in some settlements around the SNTS is not due to the close-in fallout from nuclear explosions at the SNTS, but rather
to the intensive weathering of rocks including U there. The calculated effective doses to adults resulting from consumption
of the investigated waters are in the range 1.0–18.7 μSv/y. Those doses are lower than WHO and IAEA reference value (100 μSv/y)
for drinking water. 相似文献
19.
G. Weber 《Journal of Radioanalytical and Nuclear Chemistry》1981,61(1-2):335-344
Although Neutron Activation Analysis is usually not very common in aerosol physics, there are fields of application which
seem to be rather successful. In general it is shown which properties activable aerosols should have, how they can be produced
and how aerosol samples might be drawn. By use of special aerosol separators not only the mass-concentration but also the
size-distribution of the aerosol can be determinated. Based on two studies, the utility of activable aerosols is demonstrated:
Calibration and test of a simple discontinously working aerosol monitor for the off-gass system of isotope hoods; dynamic
o radioactive ionized aerosols in a sealed room. Finally a general survey of further applications of activable aerosols is
given. 相似文献
20.
An ultra-performance liquid chromatography-tandem mass spectrometry method was developed, optimised and validated for the
quantification of synthetic folic acid (FA), also called pteroyl-l-glutamic acid or vitamin B9 and naturally occurring 5-methyltetrahydrofolate (5-MTHF) found in folate-fortified breads. Optimised
sample preparation prior to analysis involved addition of 13C5 labelled internal standards, treatments with α-amylase and rat serum, solid-phase extraction using aromatic-selective cartridges
and ultra-filtration. Analytes were separated on a Waters ACQUITY HSS T3 column during a 6-min run and analysed by positive
ion electrospray selected reaction monitoring MS/MS. Standard calibration curves for the two analytes were linear over the
range of 0.018–14 μg FA/g of fresh bread (r
2 = 0.997) and 9.3–900 ng 5-MTHF/g of fresh bread (r
2 = 0.999). The absolute recoveries were 90% and 76% for FA and 5-MTHF, respectively. Intra-day coefficients of variation were
3% for FA and 18% for 5-MTHF. The limit of detection was 9.0 ng/g for FA and 4.3 ng/g for 5-MTHF, determined using pre-extracted
tapioca starch as the blank matrix. The assay is rugged, fast, accurate and sensitive, applicable to a variety of food matrices
and is capable of the detection and quantification of the naturally occurring low levels of 5-MTHF in wheat breads. The findings
of this study revealed that the FA range in Australian fortified breads was 79–110 μg/100 g of fresh bread and suggest that
the flour may not have the mandated FA fortification level (200–300 μg/100 g of flour), though this cannot be determined conclusively
from experimental bread data alone, as variable baking losses have been documented by other authors. 相似文献