Determination of the aquatic herbicide fluridone in water and hydrosoil: effect of application method on dissipation

1981 ◽  
Vol 29 (2) ◽  
pp. 223-226 ◽  
Author(s):  
Sheldon D. West ◽  
Stanley J. Parka
Keyword(s):  
Application Method ◽  
Aquatic Herbicide

Liquid Chromatographic Determination of Fluridone Aquatic Herbicide and Its Metabolite in Fish and Crayfish

1986 ◽  
Vol 69 (5) ◽  
pp. 856-859 ◽  
Author(s):  
Sheldon D West ◽  
Edgar W Day
Keyword(s):  
Liquid Chromatography ◽  
Detection Limit ◽  
Chromatographic Determination ◽  
Reverse Phase ◽  
Reverse Phase Liquid Chromatography ◽  
Liquid Chromatographic Determination ◽  
Phase Liquid ◽  
Aquatic Herbicide ◽  
Liquid Chromatographic

Abstract A residue method is described for determination of the aquatic herbicide fluridone (1-methy1-3-phenyl-5-[3-(trifluoromethyl)phenyl]-4(1H)- pyridinone) and its metabolite (1-methy1-3-(4-hydroxyphenyl)-5-[3- (trifluoromethyl)phenyl]-4(1H)-pyridinone) in fish and crayfish tissues. Both compounds are extracted from tissues with methanol, and the extracts are subjected to acidic hydrolysis to release conjugated forms of fluridone and the metabolite. Sample extracts are purified by liquidliquid partitioning and Florisil Sep-Pak® column chromatography. Both compounds are separated and measured by reverse phase liquid chromatography with UV detection at 313 nm. In the absence of interfering peaks, the method has a detection limit of approximately 0.04 ppm of either compound. Overall, recoveries averaged 96% for fluridone and 78% for the metabolite for all tissue types combined.

Gas Chromatographic Determination of Fluridone Aquatic Herbicide and Its Major Metabolite in Fish

1980 ◽  
Vol 63 (6) ◽  
pp. 1304-1309
Author(s):  
Sheldon D West ◽  
Robert O Burger
Keyword(s):  
Electron Capture ◽  
Methyl Iodide ◽  
Fish Tissue ◽  
Chromatographic Determination ◽  
Major Metabolite ◽  
Florisil Column ◽  
Florisil Column Chromatography ◽  
Aquatic Herbicide ◽  
Liquid Chromatographic

Abstract A gas-liquid chromatographic (GLC) method is described for determining residues of the aquatic herbicide fluridone (l-methyl-3-phenyl-5-[3-(trifluoromethyl)phenyl]-4(lH)-pyridinone) and its major metabolite (l-methyl-3-(4-hydroxypherayl)-5-[3-(trifluoromethyl)phenyl]-4(lH)-pyridinone) in fish. Both compounds are extracted from fish tissue with methanol, and the extracts are subjected to acidic hydrolysis to release conjugated forms of fluridone and the metabolite. After purification by liquid-liquid partitioning, sample extracts are reacted with methyl iodide to methylate the metabolite, and then both fluridone and the metabolite are brominated with phosphorus tribromide. After purification by Florisil column chromatography, the derivatives are separated and measured by electron capture GLC. The method is capable of determining approximately 0.01 ppm of both compounds in fish, and recoveries have averaged 84±14.7% for fluridone and 83±13.4% far the metabolite.

scholarly journals Application Method of Data Mining Using the K means Algorithm for the Determination of Stress Level in High School Students Using the Beck Depression Inventory

2020 ◽  
Vol 8 (15) ◽  
pp. 1-8
Author(s):  
Felipe de Jesús Núñez Cárdenas ◽  
Eduardo Aguirre Hernández ◽  
Alain E. Guerrero Zenil ◽  
Ana María Felipe Redondo
Keyword(s):  
High School ◽  
Data Mining ◽  
High School Students ◽  
Beck Depression Inventory ◽  
Stress Level ◽  
School Students ◽  
Application Method

En el presente trabajo se realizará una descripción aplicando técnicas de minería de datos acerca de la depresión a los alumnos de educación media superior, en el cual se aplica como herramienta de evaluación el inventario de depresión Beck, así mismo mediante el algoritmo K-Means se realizará la agrupación de los datos y como resultados se busca obtener seis clusters, debido a que en la herramienta de evaluación son 6 los posibles diagnósticos que se dan de acuerdo con la puntuación obtenida.

Residue Level Determination of the Aquatic Herbicide Fluridone and a Potential Photoproduct (N-Methylformamide) in Water

1988 ◽  
Vol 71 (5) ◽  
pp. 1049-1053
Author(s):  
Sheldon D West ◽  
Larry G Turner
Keyword(s):  
Gas Chromatography ◽  
Liquid Chromatography ◽  
Water Samples ◽  
Residue Level ◽  
Vacuum Evaporation ◽  
Uv Detection ◽  
Electrolytic Conductivity ◽  
Aquatic Herbicide ◽  
Rotary Vacuum

Abstract Methods are presented for the determination of the aquatic herbicide fluridone and /V-methylformamide (NMF), a potential photoproduct of fluridone which has thus far been observed only in a laboratory aqueous photolysis study. Water samples are passed through a Sep- Pak C,8 cartridge to extract fluridone while NMF passes unretained through the cartridge with the water. Fluridone is eluted from the cartridge with methanol, which is then concentrated for analysis by liquid chromatography with UV detection at 313 nm. The water eluate containing NMF is concentrated for analysis by rotary vacuum evaporation at 40-46°C. Methanol is added to help evaporate the water, and glycerol is added as a keeper solvent to retain NMF during the evaporation. The residual NMF is dissolved in methanol for analysis by gas chromatography with a Hall electrolytic conductivity detector operated in the nitrogen mode. The assay limits of detection are 1 and 2 ppb for fluridone and NMF, respectively. Recoveries averaged 98% for fluridone at 1-400 ppb and 87% for NMF at 2- 50 ppb.

Galactic orbits of stars

1966 ◽  
Vol 25 ◽  
pp. 93-97
Author(s):  
Richard Woolley
Keyword(s):  
Globular Cluster ◽  
Potential Field ◽  
High Velocity ◽  
Velocity Vector ◽  
Variable Stars ◽  
The Sun ◽  
Proper Motions ◽  
Rr Lyrae ◽  
The Galaxy

It is now possible to determine proper motions of high-velocity objects in such a way as to obtain with some accuracy the velocity vector relevant to the Sun. If a potential field of the Galaxy is assumed, one can compute an actual orbit. A determination of the velocity of the globular clusterωCentauri has recently been completed at Greenwich, and it is found that the orbit is strongly retrograde in the Galaxy. Similar calculations may be made, though with less certainty, in the case of RR Lyrae variable stars.

Distance to SN 1987A and the LMC

1999 ◽  
Vol 190 ◽  
pp. 549-554
Author(s):  
Nino Panagia
Keyword(s):  
Angular Size ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Light Curves ◽  
Distance Modulus ◽  
Absolute Size ◽  
Sn 1987A

Using the new reductions of the IUE light curves by Sonneborn et al. (1997) and an extensive set of HST images of SN 1987A we have repeated and improved Panagia et al. (1991) analysis to obtain a better determination of the distance to the supernova. In this way we have derived an absolute size of the ringRabs= (6.23 ± 0.08) x 1017cm and an angular sizeR″ = 808 ± 17 mas, which give a distance to the supernovad(SN1987A) = 51.4 ± 1.2 kpc and a distance modulusm–M(SN1987A) = 18.55 ± 0.05. Allowing for a displacement of SN 1987A position relative to the LMC center, the distance to the barycenter of the Large Magellanic Cloud is also estimated to bed(LMC) = 52.0±1.3 kpc, which corresponds to a distance modulus ofm–M(LMC) = 18.58±0.05.

International determination of the total motion of the pole

1961 ◽  
Vol 13 ◽  
pp. 29-41
Author(s):  
Wm. Markowitz
Keyword(s):  
Secular Motion ◽  
The Future

A symposium on the future of the International Latitude Service (I. L. S.) is to be held in Helsinki in July 1960. My report for the symposium consists of two parts. Part I, denoded (Mk I) was published [1] earlier in 1960 under the title “Latitude and Longitude, and the Secular Motion of the Pole”. Part II is the present paper, denoded (Mk II).

Time and Latitude in South Africa

1972 ◽  
Vol 1 ◽  
pp. 27-38
Author(s):  
J. Hers
Keyword(s):  
South Africa ◽  
Cape Town ◽  
Astronomical Observations ◽  
Royal Observatory ◽  
The Republic ◽  
Astronomical Determination ◽  
Limited Accuracy ◽  
Better Than

In South Africa the modern outlook towards time may be said to have started in 1948. Both the two major observatories, The Royal Observatory in Cape Town and the Union Observatory (now known as the Republic Observatory) in Johannesburg had, of course, been involved in the astronomical determination of time almost from their inception, and the Johannesburg Observatory has been responsible for the official time of South Africa since 1908. However the pendulum clocks then in use could not be relied on to provide an accuracy better than about 1/10 second, which was of the same order as that of the astronomical observations. It is doubtful if much use was made of even this limited accuracy outside the two observatories, and although there may – occasionally have been a demand for more accurate time, it was certainly not voiced.

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