Exact determination of the natural modes of some Cauer filters by means of a standard analytical procedure

Abstract A modified method for the determination of dithiocarbamate fungicide residues on crops is presented. A large representative subsample of the frozen crop is blended in ice-cold deaerated water and an aliquot of the homogenate is added to the analytical apparatus containing hot 5 0% sulfuric acid. Dithiocarbamates are decomposed to evolve CS2 which is removed by a continuous gentle air-sweep from the digestion flask. Variations in technique allow the analysis of dithiocarbamate fungicide residues in several ranges, 1-10, 10-200, and 200-1000 /ig maneb. Recoveries from a wide variety of crops averaged 70 to 103%. Certain crop types present low recoveries and/or high apparent control values, but modifications in the analytical procedure are successful in solving these problems.

Download Full-text

Statistical Description of Isotope Exchange Processes: A Multisite Model for the 18O Exchange

Zeitschrift für Naturforschung C ◽

10.1515/znc-1982-11-1219 ◽

1982 ◽

Vol 37 (11-12) ◽

pp. 1161-1169 ◽

Cited By ~ 1

Author(s):

Paul Rösch

Keyword(s):

Active Site ◽

Isotope Exchange ◽

Analytical Procedure ◽

Matrix Formalism ◽

Model Calculations ◽

Exchange Processes ◽

Reaction Solution ◽

Different Types ◽

Refinement Procedure

Abstract An analytical procedure has been developed for the determination of isotope exchange processes as exemplified by the 18O exchange catalysed by enzyme-nucleotide complexes. The model is able to handle more than one type of active site per reaction solution and is also able to distinguish between different types of inequivalence of the oxygens of enzyme bound Pi. Use of transition matrix formalism and basic statistical considerations lead directly to the simple model. A data refinement procedure is introduced and model calculations are shown.

Download Full-text

Method for the simultaneous quantification of n-hexane metabolites: application to n-hexane metabolism determination

Human & Experimental Toxicology ◽

10.1177/096032719601500607 ◽

1996 ◽

Vol 15 (6) ◽

pp. 497-503 ◽

Cited By ~ 6

Author(s):

T. Soriano ◽

M. Menéndez ◽

P. Sanz ◽

M. Repetto

Keyword(s):

Similar Pattern ◽

Analytical Procedure ◽

Daily Basis ◽

Practical Application ◽

Simultaneous Quantification ◽

Exposed Workers ◽

Before And After ◽

Time Requirements ◽

The Difference

1 The described analytical procedure permits the simultaneous determination of the main n-hexane meta bolites in urine. 2-Hexanone, 2-hexanol, 2, 5-hexanediol and 2, 5-hexanedione, were chosen to dose the rats used in this study. All urine samples were collected and analysed on a daily basis, before and after acidic hydrolysis (pH 0.1) by GC/MS. 2-Hexanone, 2, 5-dimethylfurane, γ-valerolac tone and 2, 5-hexanedione were determined before hydro lysis ; 2-hexanol and 2, 5-hexanediol, after hydrolysis; and 5-hydroxy-2-hexanone and 4, 5-dihydroxy-2-hexanone were calculated by the difference between γ-valerolactone and 2, 5-hexanedione with and without hydrolysis, respectively. 2 A metabolic scheme was proposed reflecting the biotransformations undergone by the four compounds assayed. We consider 2, 5-dimethylfurane as a 'true metabolite' because the quantities detected were always greater before hydrolysis. 3 It has been reported that human and rat n-hexane metabolism follow a similar pattern. Therefore, as a practical application and without increasing either sample or time requirements, the simultaneous quantifi cation of the different metabolites and their excretion profile could provide better information about the metabolic situation of exposed workers than the determi nation of 2, 5-hexanedione alone. According to our experimental results, 4, 5-dihydroxy-2-hexanone itself would be a good toxicity indicator.

Download Full-text

III. Further experiments on the vapour densities of potassium and sodium

Proceedings of the Royal Society of London ◽

10.1098/rspl.1879.0073 ◽

1879 ◽

Vol 29 (196-199) ◽

pp. 490-493 ◽

Cited By ~ 2

Keyword(s):

Considerable Error ◽

Exact Determination ◽

The Way

In one former communication “On the Vapour Densities of Potassium and Sodium,” we pointed out the chief obstacles which lay in the way of an exact determination of these constants. Having overcome the chief manipulative difficulties in connexion with the method we described, there still remained the problem for solution as to how far the use of iron bottles in our experiments might affect the results. If the iron retained the metals or allowed their vapours to diffuse with rapidity through it, a considerable error might be produced without its being easily detected.

Download Full-text

Determination of Cd, Pb and As in sediments of the Sava river by electrothermal atomic absorption spectrometry

Journal of the Serbian Chemical Society ◽

10.2298/jsc1001113m ◽

2010 ◽

Vol 75 (1) ◽

pp. 113-128 ◽

Cited By ~ 8

Author(s):

Simona Murko ◽

Radmila Milacic ◽

Marjan Veber ◽

Janez Scancar

Keyword(s):

Nitric Acid ◽

Analytical Procedure ◽

Electrothermal Atomic Absorption Spectrometry ◽

Absorption Spectrometry ◽

Magnesium Nitrate ◽

Matrix Modifier ◽

Reliable Determination ◽

Sava River ◽

The Sava River

The applicability of nitric acid, palladium nitrate and a mixture of palladium and magnesium nitrate as matrix modifiers was estimated for the accurate and reproducible determination of cadmium (Cd), lead (Pb) and arsenic (As) in sediments of the Sava River by electrothermal atomic absorption spectrometry, ETAAS. Decomposition of the samples was done in a closed vessel microwave-assisted digestion system using nitric, hydrochloric and hydrofluoric acids, followed by the addition of boric acid to convert the fluorides into soluble complexes. The parameters for the determination of Cd, Pb and As in sediments were optimized for each individual element and for each matrix modifier. In addition, two sediment reference materials were also analyzed. In determination of Cd and Pb, nitric acid was found to be the most appropriate matrix modifier. The accurate and reliable determination of Cd and Pb in sediments was possible also in the presence of boric acid. The use of a mixture of palladium and magnesium nitrate efficiently compensated for matrix effects and enabled the accurate and reliable determination of As in the sediments. Quantification of Cd and As was performed by calibration using acid matched standard solutions, while the standard addition method was applied for the quantification of Pb. The repeatability of the analytical procedure for the determination of Cd, Pb and As in sediments was ?5 % for Cd, ?4 % for Pb and ?2 % for As. The LOD values of the analytical procedure were found to be 0.05 mg/kg for Cd and 0.25 mg/kg for Pb and As, while the LOQ values were 0.16 mg/kg for Cd and 0.83 mg/kg for Pb and As. Finally, Cd, Pb and As were successfully determined in sediments of the Sava River in Slovenia.

Download Full-text

TO THE CALCULATION OF LENGTH OF GEOPHYSICAL OBJECTS OF HYPERBOLIC OUTLINE

Prirodoobustrojstvo ◽

10.26897/1997-6011-2021-4-85-89 ◽

2021 ◽

pp. 85-89

Author(s):

K. N. ANAKHAEV ◽

◽

B. KH. AMSHOKOV ◽

K. K. ANAKHAEV

Keyword(s):

Water Management ◽

Applied Research ◽

Free Fall ◽

Linear Interpolation ◽

Close Approximation ◽

Tabular Data ◽

Exact Determination ◽

Complex Dependence ◽

Incomplete Elliptic Integrals

Hyperbolic curves are used in various theoretical and practical studies, including in the field of water management and environmental construction when calculating various geophysical objects with hyperbolic outlines (surfaces of coastal slopes, sliding lines of landslide massifs, directing dams, spillway surfaces of watersheds, water free fall trajectories, etc.). The exact determination of the length of the hyperbola arc is represented by a rather complex dependence based on “unbreakable” incomplete elliptic integrals, which makes it difficult to carry out analytical calculations and involves the use of tabular data with a time-consuming cross and non-linear interpolation of them, etc. Elementary dependencies are proposed to determine the length of the hyperbola arc, which give a very close approximation (up to 1%) to exact values. The obtained calculated analytical dependencies for determining the length of the hyperbola arc are recommended for practical use in theoretical and applied research in various fi elds of science and technology.

Download Full-text