Dosage du Sr-90 dans l'eau des lacs et des rivières du Québec par précipitation avec l'oxine et comptage β

1988 ◽  
Vol 66 (1) ◽  
pp. 174-177 ◽  
Author(s):  
E. Haddad ◽  
L. Zikovsky
Keyword(s):  
Detection Limit ◽  
Surface Waters ◽  
New Method ◽  
The Mean ◽  
Better Than

A new method for the determination of Sr-90 dissolved in surface waters has been developed. It is based on the precipitation of Sr with 8-hydroxyquinoline at pH 11.3 and counting of β particles with energy above 150 keV. The detection limit obtained is 0.5 mBq/L and the mean yield is 28%. The decontamination factors from other β emitters achieved are better than 10 000. This method has been used to measure the Sr-90 in 5 lakes and 5 rivers in Québec and activities ranging from 3 to 15 mBq/L were obtained. This new method is as efficient and reliable as conventional techniques while being less tedious.

scholarly journals An Advanced Method to Estimate Deep Currents from Profiling Floats

2005 ◽  
Vol 22 (8) ◽  
pp. 1294-1304 ◽  
Author(s):  
Jong Jin Park ◽  
Kuh Kim ◽  
Brian A. King ◽  
Stephen C. Riser
Keyword(s):  
Indian Ocean ◽  
Accurate Determination ◽  
New Method ◽  
Advanced Method ◽  
Subsurface Ocean ◽  
Least Squares Fit ◽  
Geostrophic Shear ◽  
The Mean ◽  
Better Than

Abstract Subsurface ocean currents can be estimated from the positions of drifting profiling floats that are being widely deployed for the international Argo program. The calculation of subsurface velocity depends on how the trajectory of the float while on the surface is treated. The following three aspects of the calculation of drift velocities are addressed: the accurate determination of surfacing and dive times, a new method for extrapolating surface and dive positions from the set of discrete Argos position fixes, and a discussion of the errors in the method. In the new method described herein, the mean drift velocity and the phase and amplitude of inertial motions are derived explicitly from a least squares fit to the set of Argos position fixes for each surface cycle separately. The new method differs from previous methods that include prior assumptions about the statistics of inertial motions. It is concluded that the endpoints of the subsurface trajectory can be estimated with accuracy better than 1.7 km (East Sea/Sea of Japan) and 0.8 km (Indian Ocean). All errors, combined with the error that results from geostrophic shear and extrapolation, should result in individual subsurface velocity estimates with uncertainty of the order of 0.2 cm s−1.

scholarly journals Determination of Atrazine in Water by Magnetic Particle Immunoassay: Collaborative Study

1996 ◽  
Vol 79 (2) ◽  
pp. 529-537 ◽  
Author(s):  
Mary C Hayes ◽  
Scott W Jourdan ◽  
David P Herzog ◽  
P Barnes ◽  
C Charan ◽  
...  
Keyword(s):  
Detection Limit ◽  
Water Sample ◽  
Magnetic Particle ◽  
Collaborative Study ◽  
Study Data ◽  
Collaborative Studies ◽  
Enzyme Conjugate ◽  
Repeatability And Reproducibility ◽  
The Mean

Abstract A collaborative study was performed to determine mean recovery and precision for analysis of atrazine in drinking and surface waters by immunoassay. The study design was based on the blind duplicate test plan for collaborative studies. Three blank waters (municipal drinking water, well water, and surface water) were spiked at 3 atrazine levels. Two water samples with naturally incurred atrazine loads were also spiked with atrazine at 3 levels. In the enzyme-linked immunoassay method, the water sample is mixed with a pesticide–enzyme conjugate and added to paramagnetic particles with triazine-specific antibodies attached. After separation of antibody-bound atrazine and atrazine–enzyme conjugate from free components, the bound enzyme conjugate catalyzes a reaction producing a colored end product. The color developed is inversely proportional to the original concentration of atrazine in the water sample. Fourteen laboratories participated in the collaborative study. Data were analyzed for repeatability and reproducibility, and average recoveries at the spike levels were calculated. Over the concentration range tested, the mean recovery of atrazine spiked into blank and pesticide-contaminated waters was 104%. Overall RSDRaveraged about 40% for atrazine concentrations near the method detection limit (0.05 μg/L) and about 15% at concentrations above 5 times the detection limit (0.25 μg/L). Corresponding single-analyst RSDr values were 24 and 10%. Recovery and precision for the 3 blank water matrixes and the waters that had been naturally contaminated with atrazine showed no significant differences. The magnetic particle immunoassay

Determination of Ibuprofen in Human Plasma and Urine by Gas Chromatography/Mass Spectrometry

2014 ◽  
Vol 97 (2) ◽  
pp. 415-420 ◽  
Author(s):  
Bilal Yilmaz ◽  
Ali Fuat Erdem
Keyword(s):  
Human Plasma ◽  
Internal Standard ◽  
Gas Chromatography Mass Spectrometry ◽  
Oral Tablet ◽  
Liquid Liquid Extraction ◽  
Human Plasma And Urine ◽  
The Mean ◽  
Interday Precision ◽  
Better Than

Abstract This paper describes a GC/MS method for the determination of ibuprofen in human plasma and urine. Ibuprofen and internal standard naproxen were extractedfrom plasma and urine by using a liquid–liquid extraction method. Derivatization was carried outusing N-methyl-N-(trimethylsilyl) trifluoroacetamide. Calibration curves were linear over the concentration range of 0.05–5.0 and 0.1–10.0 μg/mL for plasma and urine, respectively. Intraday and interday precision (RSD) values for ibuprofen in plasma and urine were less than 6.31%, and accuracy (relative error) was better than 12.00%. The mean recovery of ibuprofen was 89.53% for plasma and 93.73% for urine. TheLOD was 0.015 and 0.03 μg/mL and the LOQ was 0.05 and 0.1 μg/mL for plasma and urine, respectively. The method was successfully applied to blood samples from three healthy male volunteers who had been given an oral tablet of 600 mg ibuprofen.

scholarly journals Hipparcos, Three Years After Launch

1993 ◽  
Vol 156 ◽  
pp. 1-10
Author(s):  
J. Kovalevsky ◽  
M. Froeschlé
Keyword(s):  
Standard Error ◽  
Present Status ◽  
Double Star ◽  
New Method ◽  
Standard Errors ◽  
First Year ◽  
Mass Determination ◽  
Mission Duration ◽  
The Mean

In a first part, the present status of the HIPPARCOS mission is described. Despite the degradations and failures of gyroscopes, it is still hoped that a 4 1/2 mission duration will be reached. The first-year of data has been reduced by both FAST and NDAC consortia. For the best 46200 observed stars, the distribution of standard errors in positions has a maximum of 1.5 mas in latitude and 1.8 mas in longitude and the mean standard error for parallaxes is of the order of 3 mas. The comparison of results obtained by both consortia shows that the differences are small and quite consistent with the announced internal precisions. Magnitude measurements are precise to 0.02 magnitude for a 4 second observation. The precision to be expected for double star observations is also given. The main new result is that the magnitudes of the components are obtained with a few hundredths of a magnitude precision. This allows to devise a new method of mass determination based upon the parallax and a recalibrated mass-luminosity diagram. The parallax dependence of the results is much more favourable than in the case of the classical determination of masses using orbital motions.

The Determination of Traces of Bismuth by Solid State Luminescence

1974 ◽  
Vol 52 (10) ◽  
pp. 1942-1944 ◽  
Author(s):  
D. E. Ryan ◽  
H. Rollier ◽  
J. Holzbecher
Keyword(s):  
Detection Limit ◽  
Solid State ◽  
Calcium Oxalate ◽  
Co Precipitation ◽  
State Luminescence ◽  
Better Than

Traces of Bi(III) are determined with good selectivity by measurement of the luminescence (λex = 355 nm; λem = 430 nm) of CaO:Bi phosphor after co-precipitation with calcium oxalate and ignition at 850–900 °C. The detection limit is better than 0.01 μg Bi in 15 mg CaO; bismuth can be quantitatively recovered from 500 ml sample volumes and analysis is possible for 0.02 ng Bi/ml. The method has been successfully applied to the determination of trace amounts of bismuth added to synthetic blood and kidney samples.

Frequency resolution of Fourier and maximum entropy spectral estimates

Geophysics ◽  
1982 ◽  
Vol 47 (9) ◽  
pp. 1303-1307 ◽  
Author(s):  
S. L. Marple
Keyword(s):  
Maximum Entropy ◽  
Signal To Noise Ratio ◽  
Frequency Resolution ◽  
Sampled Data ◽  
Signal To Noise ◽  
Analytic Determination ◽  
Spectral Estimates ◽  
The Mean ◽  
Better Than

An analytic determination of the frequency resolution for maximum entropy and conventional Blackman‐Tukey spectral estimates is made for the case of known autocorrelation. As the signal‐to‐noise ratio decreases, the maximum entropy resolution is no better than that achievable by the Blackman‐Tukey spectral estimate. The mean resolution of an ensemble of spectra constructed from sampled data sequences agrees with the analytic result.

Automated Spectrophotometric Method Using 2,2’-Dithiodipyridine Acid for Determination of Cholinesterase in Whole Blood

1996 ◽  
Vol 79 (3) ◽  
pp. 757-763 ◽  
Author(s):  
Jose J Cerón ◽  
María J Fernandez Del Palacio ◽  
Luis J Bernal ◽  
Cándido Gutierrez
Keyword(s):  
Detection Limit ◽  
Spectrophotometric Method ◽  
Whole Blood ◽  
Cholinesterase Activity ◽  
New Method ◽  
Good Precision ◽  
Throughput Rate ◽  
Nitrobenzoic Acid ◽  
Automated Method

Abstract An automated method using 2,2’-dithiodipyridine (2-PDS) as chromophore for determination of wholeblood cholinesterase activity was developed. Assay procedures, optimal concentrations of chromophore and substrate, detection limit, precision, backgrounds, and sensitivity of the method were compared with those of an earlier automated method based on the Eilman method and using 5,5’-dithiobis(2-nitrobenzoic acid) (DTNB) as chromophore. The new method has the advantages of automation (resulting in increase throughput rate and decrease in amount of reagents used) and good precision and sensitivity. Sample dilutions also are reduced in the new method because hemoglobin interference is less.

Automated method for determination of mercury in urine.

1976 ◽  
Vol 22 (10) ◽  
pp. 1604-1607 ◽  
Author(s):  
R A Richardson
Keyword(s):  
Detection Limit ◽  
Atomic Absorption ◽  
Coefficient Of Variation ◽  
Flameless Atomic Absorption ◽  
Automated Method ◽  
Atomic Absorption Technique ◽  
Mercury In Urine ◽  
The Mean ◽  
Absorption Technique

Abstract I describe a sensitive, specific, automated method for determination of mercury in urine by the "flameless atomic absorption" technique. One can analyze 20 samples per hour, with less than 0.5-ml samples of urine. The detection limit is 0.01 mumol/liter (2mug/liter) and the mean coefficient of variation 12%. The procedure is being used to monitor mercury excretion by workers exposed to mercury.

scholarly journals New Method of Denitrification Analysis of Bradyrhizobium Field Isolates by Gas Chromatographic Determination of 15N-Labeled N2

2004 ◽  
Vol 70 (5) ◽  
pp. 2886-2891 ◽  
Author(s):  
Reiko Sameshima-Saito ◽  
Kaori Chiba ◽  
Kiwamu Minamisawa
Keyword(s):  
Thermal Conductivity ◽  
Detection Limit ◽  
Bradyrhizobium Japonicum ◽  
Chromatographic Determination ◽  
New Method ◽  
Thermal Conductivity Detector ◽  
Gas Chromatograph ◽  
Carrier Gas ◽  
Field Isolates

ABSTRACT To evaluate the denitrification abilities of many Bradyrhizobium field isolates, we developed a new 15N-labeled N2 detection methodology, which is free from interference from atmospheric N2 contamination. 30N2 (15N15N) and 29N2 (15N14N) were detected as an apparent peak by a gas chromatograph equipped with a thermal conductivity detector with N2 gas having natural abundance of 15N (0.366 atom%) as a carrier gas. The detection limit was 0.04% 30N2, and the linearity extended at least to 40% 30N2. When Bradyrhizobium japonicum USDA110 was grown in cultures anaerobically with 15NO3 −, denitrification product (30N2) was detected stoichiometrically. A total of 65 isolates of soybean bradyrhizobia from two field sites in Japan were assayed by this method. The denitrification abilities were partly correlated with filed sites, Bradyrhizobium species, and the hup genotype.

Determination of Inorganic Selenium Species in Marine Waters by Hydride Generation - AFS

2004 ◽  
Vol 57 (10) ◽  
pp. 937 ◽  
Author(s):  
Bronwyn D. Wake ◽  
Edward C. V. Butler ◽  
Alison M. Featherstone ◽  
Patti Virtue ◽  
Bernard Averty ◽  
...  
Keyword(s):  
Detection Limit ◽  
Fluorescence Detection ◽  
Hydride Generation ◽  
Reduction Step ◽  
Marine Waters ◽  
Atomic Fluorescence ◽  
Inorganic Selenium ◽  
Cryogenic Trapping ◽  
Better Than

A method based on hydride generation with cryogenic trapping and atomic fluorescence detection was developed that is capable of determining both inorganic Se species (SeIV and SeVI) while at sea. Evaluation of the system for optimal performance was made for each stage of the analysis and detection sequence, as well as for the SeVI reduction step. A detection limit of 0.4 ng L−1 Se in a 10 mL sample was achieved using this method. Precision was better than 3.5% for 25, 100, and 1000 ng L−1 SeIV standard solutions. Accuracy was determined by recovery studies using natural samples and a certified reference seawater (NASS-5).

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