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1.
The determination of gold is based on the photoexcitation reaction 197Au(γ,γ’)197mAu with the half-life of 7.73 seconds and energy of emitted gamma-rays of 279 keV. Three 100 ml aliquots of coarsely ground
Au-ore (grains <2 mm) corresponding to ca. 150–180 g were irradiated for 20 seconds with bremsstrahlung of maximum energy
10 MeV produced by a microtron at the electron beam current of 30–40 μA, 1–10 times reactivation was applied. After 3 seconds
of decay, samples were measured for 20 seconds using scintillation or semiconductor gamma-spectrometry with the detection
limits for an ideal sample down to 0.5 μg·g−1 and 0.1–0.2 μg·g−1 of Au, respectively. Content of U and Th undergoing photo-fission increases the detection limits several times. 相似文献
2.
Summary A simple and sensitive method for the determination of trace amounts of bisphenol-A (BPA), bisphenol-A diglycidyl dimethacrylate
(bis-GMA), bisphenol-A dimethacrylate (bis-DMA) and triethyleneglycol dimethacrylate (TEGDMA) in human saliva is proposed.
These materials are used in dental restorations, as composites and sealants, and are sometimes detected in human saliva after
dental treatment. The proposed method involves protein precipitation using acetonitrile followed by acidification, evaporation
of the solvent and dissolution with dichloromethane prior to injection into a GC-MS.
Thermal derivatization in the injection system was used for the identification and quantification of bis-GMA. Clean-up is
not necessary using SIM mode. Bisphenol-F (BPF) was used as internal standard. The linear range was 15 to 1000 μg·L−1 for BPA, 50 to 10 000 μg·L−1 for bis-GMA, 50 to 1000 μg·L−1 for bis-DMA and 1 to 100 μg·L−1 for TEGDMA.
The detection limits were 3,15,10 and 0.3 μg·L−1 for BPA, bis-GMA, bis-DMA and TEGD-MA, respectively. Validation of the proposed method was carried out by using the standard
addition methodology.
Samples of 10 mL of human saliva collected 1 h after dental treatment were analysed in order to assess the applicability of
the method to detect and quantify such compounds originated from methacrylic resins used in odontological treatment. 相似文献
3.
S. N. Shilobreeva N. Dogadkin Ph. J. Potts 《Journal of Radioanalytical and Nuclear Chemistry》1999,240(1):47-52
Beta autoradiography and progressive acid leaching have been used to investigate the distribution of Ir in silicates in the
presence of carbon phases as well as without these phases. Determinations of Ir by neutron activation analysis gave results
for the Ir content of basaltic glasses after experiments at 1 bar of 82 ng·g−1 (NNO buffer), 30 ng·g−1 (CCO equilibrium) and 37 ng·g−1 (IW buffer). Iridium solubility in basaltic melt in the presence of graphite and (CO, CO2) fluid increased from 1.6 μg·g−1 at 0.5 kbar to 6.2 μg·g−1 at 2 kbar. These data give Ir partition coefficients between solid metal and liquid silicate in the presence of carbon phases.
Discrete (Ir, Fe) rich phases were discovered in the basaltic melt at 3 kbar and 1250°C preventing the determination of solubility
data. Our results provide clear evidence that the iridium solubility in a basaltic melt in the presence of carbon is higher
than the solubility of iridium in melts without carbon. 相似文献
4.
R. K. Singhal J. Preetha Rupali Karpe P. Hema Ajay Kumar V. M. Joshi A. K. Ranade A. G. Hegde 《Journal of Radioanalytical and Nuclear Chemistry》2009,279(1):301-306
During this work the determination of uranium in the range of μg·L−1 to tens of μg·L−1 was done by alpha-spectrometry after electroplating the aliquots of water sample using (NH4)2SO4 as an electrolyte. In general, the determination of uranium by alpha-spectrometry needs its separation from other transuranics
specially thorium. The process described here does not involve any sample digestion and radiochemical separation of uranium
from other transuranics. In this method an aliquot (1 to 3 mL) of the sample was dried and dissolve in (NH4)2SO4 and thereafter the sample was electroplated on a stainless steel (SS) planchet by using an electrochemical cell of special
design. The proposed techniques have a distinct advantage over the determination of uranium by adsorptive stripping voltammetry
(AdSV) in which uranium-chloranilic (2,5-dichloro-3,6-dihydroxy-1,4-benzoquinone) acid complex was used for concentrating
the uranium from the solution. Since in the case of AdSv, the determination of uranium was not possible for samples having
dissolved organic carbon (DOC) more than 15 mg·L−1 and Cl− concentration is in the range of 40,000 μ·g−1. In the case of spike experiments with 232U the recovery was observed in the range of 90–95% in aqueous medium having higher concentration of Cl− and DOC as indicated above. 相似文献
5.
Chen HQ Wang L Liu Y Wu WL Liang AN Zhang XL 《Analytical and bioanalytical chemistry》2006,385(8):1457-1461
A new fluorescence method for the detection of proteins with novel composite nanoparticles (CdS/PPA) has been developed. The
composite nanoparticles have been prepared through an in-situ polymerization method under ultrasonic irradiation. The surface
of the composite nanoparticles was covered with functional groups (-COOH). These groups may play a major role in the improving
the water solubility and biocompatibility of the nanoparticles. The composite particles is combined with proteins in NaAc-HCl
buffer solution (pH=1.99), which can result in strong fluorescence, and the response is linearly proportional to the concentration
of proteins. In λem/λex=650 nm/365 nm place (the stoke’ shift is 285 nm), its fluorescent strength reaches the maximum. Under
the optimum conditions, the linear range is 0.10–20.0 μg·ml−1 with the detection limit of 41 ng·ml−1 for HSA, and 0.10–15.0 μg·ml−1 with the detection limit of 35 ng·ml−1 for Human γ-IgG . The method has been applied to the determination of the total protein in human serum samples collected
from the hospital and the results are satisfactory. 相似文献
6.
C. Giachetti 《Chromatographia》1998,48(5-6):443-449
Summary Low amounts of triethanolamine, collected in ORBO 53 tubes during air sampling, required the development of a very sensitive
method for determination. After desorption and silylation reaction with trimethylsilyl imidazole/trimethyl chlorosilane, the
derivative was analyzed by gas chromatography-mass spectrometry on an Ultra 2 silica capillary column in single ion monitoring
mode (retention time: about 6 min). The method has a detection limit of 1–2 pg with a desorption efficiency of about 81%.
Linearity of response was ascertained in the ranges 10–100 ng and 100–1000 ng. Short-term method validation was carried out
by intra- and inter-day assays on three amounts for each reference calibration curve. All results satisfied the pre-defined
acceptance criteria. In general, the whole procedure was easily performed and was appropriate for our needs. Breakthrough
volume was appropriate for our needs. Breakthrough volume was determined on authentic samples and was about 40–60 L, using
a flow rate of 1 L·min−1. The amounts of triethanolamine found in the samples ranged from 150 to 250 ng (about 2.5–4.2 μg·m−3). 相似文献
7.
P. Bock Ch. Engelmann A. Hatterer 《Journal of Radioanalytical and Nuclear Chemistry》1977,38(1-2):97-106
Carbon and nitrogen are determined by means of the photonuclear reactions:12C(γ n)11C and14N(γ, n)13N. This article presents a simultaneous chemical separation method for the isolation of11C and13N. It is based mainly on combustion of the sample, after irradiation and etching, in a mixture of oxidising acid fused salts
(B2O3 and Pb3 O4) containing a dispersing agent (NaCl and KCl) and the respective carriers. Each analysis takes about 40 min altogether. Minimum
carbon and nitrogen contents of a few 10−2 μg·g−1 can be measured. The influence of the main competitive nuclear reactions on neighbouring elements, including the sodium itself,
is examined. 相似文献
8.
Tatyana S. Baptista Marcelo M. Redígolo Cibele B. Zamboni Ivone M. Sato Jose R. Marcelino 《Journal of Radioanalytical and Nuclear Chemistry》2012,291(2):399-403
The World Health Organization states that envenomation is responsible for a high number of deaths per year, especially in
equatorial areas. The only effective specific treatment is the use of hyperimmune serum (antivenom). In Brazil, Crioula breed
horses are used for antivenom production, with great importance in the maintenance of public health programs. A strict biochemical
and metabolic control is required to attain specificity in antiserum. Inorganic elements represent only a small fraction of
whole blood. Nonetheless, they play important roles in mammalian metabolism, being responsible for controlling enzymatic reactions,
respiratory and cardiac functions and ageing. In this work, whole blood samples from Crioula breed horses were analyzed by
EDXRF technique. The reference interval values were determined for the elements Na (1955–2013 μg g−1), Mg (51–75 μg g−1), P (523–555 μg g−1), S (1628–1730 μg g−1), Cl (2388–2574 μg g−1), K (1649–1852 μg g−1), Ca (202–213 μg g−1), Cu (4.1–4.5 μg g−1) and Zn (2.4–2.8 μg g−1) and a comparative study with NAA results was outlined. The samples were obtained from Instituto Butantan. Both techniques
showed to be appropriate for whole blood sample analyses and offer a new perspective in Veterinary Medicine. 相似文献
9.
Summary Gas chromatographic conditions for determining eight phenylurea (chlortoluron, diuron, fluometuron, isoproturon, linuron,
metabenzthiazuron, metobromuron and monuron) and one sulfonylurea (chlorsulfuron) herbicides were assessed. Degradation products
of the herbicides formed in the injector were used for identification. Most phenylureas formed their respective carbamic acid
methyl esters, metabenzthiazuron formed an aminobenzothiazol and chlorsulfuron formed an aminotriazine plus a phenylsulfonamide.
On-column injection of standards using a BP10 capillary column was evaluated to identify the chromatographic behaviour. Detection
limits ranged from 0.05 ng for chlorsulfuron to 3 ng for monuron with the NPD and, from 0.01 ng for chlorsulfuron to 5 ng
for metabenzthiazuron with the ECD. The RSDs (n=4) were lower than 4% at the 12–25 ng level.
The method was applied to the analysis of surface waters extracted with C18 Empore disks with recoveries higher than 85%.
Each herbicide could be determined in water down to 0.1 μg·L−1. Chlortoluron was found (11.4 μg·L−1) in a water sample and its presence was confimed by gas chromatography-mass spectrometry. 相似文献
10.
The cadmium ratios of 52 short-lived nuclides have been measured. Epithermal neutron irradiation reduces the activities of20F,27Mg,28Al,38Cl,49Ca,46mSc,51Ti,56Mn and66Cu by factors of 20–30. The calculated improvements in detection limits for Ga, Br, Rb, Y, Mo, Rh, Pd, Ag, In, Sn, Sb, I,
Ba, Nd, Sm, Gd, Dy, Er, Yb, Hf, W, Re, Pt, Au, Th and U are in the range 1–6. Hafnium was measured in USGS rocks: AGV-1 (4.9
μg g−1), G-2 (7.5 μg g−1) and GSP-1 (14.7 μg g−1) and IAEA standards: SOIL-5 (6.3 μg g−1 and SL-1 (4.6 μg g−1). CCRMP reference concentrates PTC and PTM were analysed for rhodium (1.1 and 0.75 μg g−1, respectively) and silver (69 and 5.8 μg g−1, respectively). 相似文献
11.
C. Olivier H. A. Ras M. Peisach 《Journal of Radioanalytical and Nuclear Chemistry》1982,70(1-2):311-327
Simultaneous determination of the two stable boron isotopes was carried out through the measurement of proton induced 2124
keV gamma-ray from11B and 428 keV or 718 keV gamma-rays from10B. Excitation functions were constructed and mean energies for thick target range corrections were calculated. Analysis requires
no target preparation. Bombardments last up to 30 min. The sensitivity limit for total boron is 150 μg·g−1 and for isotopic determinations, 0.50 atom%. The relative precision is about 3%. 相似文献
12.
When trypsin reacts with Herring sperm DNA (hsDNA), Salmon sperm DNA (sDNA), and Calf thymus DNA (ctDNA) to form a complex,
the resonance Rayleigh scattering (RRS) was remarkably enhanced and new RRS spectra appear. These new spectra have similar
characteristics of RRS spectra. The maximum RRS peaks are at 307 nm (hsDNA, sDNA) and 290 nm (ctDNA), and other peaks are
at 350 nm. The scattering intensity is proportional to the concentration of DNA or trypsin; so this intereaction can be used
to determine trypsin using DNA or DNA using trypsin. In the determination of DNA using trypsin, the linear ranges for hsDNA,
sDNA, and ctDNA are 0–2.3, 0–2.5, and 0–1.9 μg·mL−1, and the detection limits are 0.4, 0.7, and 1.1 ng·mL−1, respectively. In the determination of trypsin using hsDNA, the linear range is 0–30.0 μg·mL−1, and the detection limit is 39.0 ng·mL−1. In this paper, the intereaction conditions were optimized. The affecting factors, chemical properties of the complex, and
the composition ratio of trypsin with DNA were investigated. Using trypsin as RRS probe, a sensitive method for the determination
of trace amounts of DNA was developed.
Translated from Chemical Journal of Chinese Universities, 2006, 27(3) (in Chinese) 相似文献
13.
Ph. Goodall 《Journal of Radioanalytical and Nuclear Chemistry》1999,240(1):5-13
The development of a spectrophotometric method for the determination of hydrogen peroxide in uranyl nitrate solutions is reported.
The method involves the measurement of the absorbance at 520 nm of a vanadyl peroxide species. This species was formed by
the addition of a reagent consisting of vanadium (V) (50 mmol·dm−3) in dilute sulphuric acid (2 mol·dm−3 H2SO4). This reagent, after dilution, was also used as an extractant for organic phase samples. The method is simple and robust
and tolerant of nitric acid and U(VI). Specificity and accuracy were improved by the application of solid phase extraction
techniques to remove entrained organic solvents and Pu(IV). Reverse phase solid phase extraction was used to clean-up aqueous
samples or extracts which were contaminated with entrained solvent. A solid phase extraction system based upon an extraction
chromatography system was used to remove Pu(IV). Detection limits of 26 μmol·dm−3 (0.88 μg·cm−3) or 7 μmol·dm−3 (0.24 μg·cm−3) for, respectively, a 1 and 4 cm path length cell were obtained. Precisions of RSD=1.4% and 19.5% were obtained at the extremes
of the calibration curve (5 mmol·dm−3 and 50 μmol·dm−3 H2O2, 1 cm cell). The introduction of the extraction and clean-up stages had a negligible effect upon the precision of the determination.
The stability of an organic phase sample was tested and no loss of analyte could be discerned over a period of at least 5
days. The presence of trace levels of reductants interfered with the determination, e.g., hydrazine (<2 mmol·dm−3), but this effect was ameliorated by increasing the concentration of the colormetric reagent. 相似文献
14.
A new adsorbent is proposed for the solid-phase extraction of phenol and 1-naphthol from polluted water. The adsorbent (TX-SiO2) is an organosilica composite made from a bifunctional immobilized layer comprising a major fraction (91%) of hydrophilic
diol groups and minor fraction (9%) of the amphiphilic long-chain nonionic surfactant Triton X-100 (polyoxyethylated isooctylphenol)
(TX). Under static conditions phenol was quantitatively extracted onto TX-SiO2 in the form of a 4-nitrophenylazophenolate ion associate with cetyltrimethylammonium bromide. The capacity of TX-SiO2 for phenol is 2.4 mg g−1 with distribution coefficients up to 3.4 × 104 mL g−1; corresponding data for 1-naphthol are 1.5 mg g−1 and 3 × 103 mL g−1. The distribution coefficient does not change significantly for solution volumes of 0.025–0.5 L and adsorbent mass less than
0.03 g; 1–90 μg analyte can be easily eluted by 1–3 mL acetonitrile with an overall recovery of 98.2% and 78.3% for phenol
and 1-naphthol, respectively. Linear correlation between acetonitrile solution absorbance (A
540) and phenol concentration (C) in water was found according to the equation A
540 = (6 ± 1) × 10−2 + (0.9 ± 0.1)C (μmol L−1) with a detection range from 1 × 10−8 mol L−1 (0.9 μL g−1) to 2 × 10−7 mol L−1 (19 μL g−1), a limit of quantification of 1 μL g−1 (preconcentration factor 125), correlation coefficient of 0.936, and relative standard deviation of 2.5%. A solid-phase colorimetric
method was developed for quantitative determination of 1-naphthol on adsorbent phase using scanner technology and RGB numerical
analysis. The detection limit of 1-naphthol with this method is 6 μL g−1 while the quantification limit is 20 μL g−1. A test system was developed for naked eye monitoring of 1-naphthol impurities in water. The proposed test kit allows one
to observe changes in the adsorbent color when 1-naphthol concentration in water is 0.08–3.2 mL g−1. 相似文献
15.
A rapid and simple procedure for the determination of antioxidants and preservatives in cosmetics has been developed utilizing
solid-phase microextraction combined with GC–MS. A silica fiber coated with polyacrylate provided the highest extraction efficiency.
Detection limits in the range from 0.4 to 8.5 ng mL−1 were obtained. Linearity is over a wide range from 1 to 2,000 ng mL−1 with a relative standard deviation under 16%. Cosmetic from a local supermarket were analysed for antioxidants and preservatives
to demonstrate the effectiveness of the proposed method. The concentration of antioxidants and preservatives determined was
20–1,218 μg g−1 for methylparaben and 5–3,779 μg g−1 for propylparaben. 相似文献
16.
Summary A rapid and accurate HPLC method is described for the simultaneous determination of acetaminophen, dextromethorphen hydrobromide
and pseudoephedrine hydrochloride in a new cold formulation. Chromatographic separation of the three pharmaceuticals was performed
on a Hypersil CN column (150×5.0 mm, 5 μm) with a mobile phase mixture of an ion-pairing solution, methanol and acetonitrile
(25:57:18, v/v), at a flow rate of 1.0 mL min−1, with detection at 220 nm. Separation was complete in less than 10 min. The method was validated for linearity, accuracy,
precision, limit of quantitation and robustness. Linearity, accuracy, and precision were found to be acceptable over the ranges
of 2.06∼20.6 μg·mL−1 for acetaminophen, 0.202∼2.02 mg·mL−1 for pseudoephedrine hydrochloride and 0.042∼1.06 mg·mL−1 for dextromethorphen hydrobromide. 相似文献
17.
Annibaldi A Truzzi C Illuminati S Bassotti E Scarponi G 《Analytical and bioanalytical chemistry》2007,387(3):977-998
Eight PM10 aerosol samples were collected in the vicinity of the “Mario Zucchelli” Italian Antarctic Station (formerly Terra
Nova Bay Station) during the 2000–2001 austral summer using a high-volume sampler and precleaned cellulose filters. The aerosol
mass was determined by differential weighing of filters carried out in a clean chemistry laboratory under controlled temperature
and humidity. A two-step sequential extraction procedure was used to separate the water-soluble and the insoluble (dilute-HCl-extractable)
fractions. Cd, Pb and Cu were determined in the two fractions using an ultrasensitive square wave anodic stripping voltammetric
(SWASV) procedure set up for and applied to aerosol samples for the first time. Total extractable metals showed maxima at
midsummer for Cd and Pb and a less clear trend for Cu. In particular, particulate metal concentrations ranged as follows:
Cd 0.84–9.2 μg g−1 (average 4.7 μg g−1), Pb 13.2–81 μg g−1 (average 33 μg g−1), Cu 126–628 μg g−1 (average 378 μg g−1). In terms of atmospheric concentration, the values were: Cd 0.55–6.3 pg m−3 (average 3.4 pg m−3), Pb 8.7–48 pg m−3 (average 24 pg m−3), Cu 75–365 pg m−3 (average 266 pg m−3). At the beginning of the season the three metals appear widely distributed in the insoluble (HCl-extractable) fraction (higher
proportions for Cd and Pb, 90–100%, and lower for Cu, 70–90%) with maxima in the second half of December. The soluble fraction
then increases, and at the end of the season Cd and Pb are approximately equidistributed between the two fractions, while
for Cu the soluble fraction reaches its maximum level of 36%. Practically negligible contributions are estimated for crustal
and sea-spray sources. Low but significant volcanic contributions are estimated for Cd and Pb (∼10% and ∼5%, respectively),
while there is an evident although not quantified marine biogenic source, at least for Cd. The estimated natural contributions
(possibly including the marine biogenic source) cannot account for the high fractions of the metal contents, particularly
for Pb and Cu, and this suggests that pollution from long-range transport is the dominant source.
Figure Aerosol sampling in Antarctica 相似文献
18.
Summary Headspace-gas chromatography was used to determine the contents of toxic 1,4-dioxane, ethylene oxide and ethylene glycol in
ethoxylated alcohols and alkylamines, and in commercial cosmetics and washing products. A Permaphase PEG capillary column
was used for the determination of 1,4-dioxane and ethylene oxide and a DB-17 column for ethylene glycol determination. Dimethylformamide
was used as the solvent in the determination of 1,4-dioxane and ethylene oxide, and undecanol in the case of ethylene glycol.
The detection limits for ethylene oxide, 1,4-dioxane and ethylene glycol are 1,2 and 10 μg·g−1, respectively. 相似文献
19.
Regular hexagonal Co–Al layered double hydroxides (Co–Al LDH) were synthesized by urea-induced homogeneous precipitation.
This material proved to be nanosheets by scanning electron microscopy and X-ray diffraction measurements. The electrochemical
capacitive behavior of the nanosheets in 1 M KOH solution were evaluated by constant current charge/discharge and cyclic voltammetric
measurements, showing a large specific capacitance of 192 F·g−1 even at the high current density of 2 A·g−1. When multiwall carbon nanotubes (MWNTs) were mixed with the Co–Al LDH, it was found that the specific capacitance and long-life
performance of all composite electrodes at high current density are superior to pure LDH electrode. When the added MWNTs content
is 10 wt%, the specific capacitance increases to 342.4 F·g−1 and remains at a value of 304 F·g−1 until the 400th cycle at 2 A·g−1, showing that this is a promising electrode material for supercapacitors working at heavy load. According to the electrochemical
impedance spectra, MWNTs greatly increase the electronic conductivity between MWNTs and the surface of Co–Al LDH, which consequently
facilitates the access of ions in the electrolyte and electrons to the electrode/electrolyte interface. 相似文献
20.
R. Cornelis J. Versieck L. Mees J. Hoste F. Barbier 《Journal of Radioanalytical and Nuclear Chemistry》1980,55(1):35-43
Vanadium in serum has been investigated by the aid of neutron activation analysis (8 min irradiation at 8·1013 n·cm−2·s−1 in the reactor FR-II of the Kernforschungszentrum in Karlsruhe). The lyophilized samples were dry-ashed before irradiation
and the52V activity extracted after irradiation. The values for V in the sera of 22 healthy males ranged from 0.029–0.939 ng V·ml−1. There is a real assumption that some of the high figures are due to persons being contaminated with V. The 18 healthy females
yielded a mean value of 0.033±0.012 ng V·ml−1 for 17 of them and one additional value of 0.139 ng V·ml−1. These V-data are the lowest ever reported in the literature. The analyses of two packed blood cell samples yielded 0.031
and 0.020 ng·g−1, indicating that about 68% of the total V in blood is present in serum. There was no correlation between the V-content and
age, nor between the V-content and the cholesterol, triglycerides or the lipoprotein fractions in serum. 相似文献