scholarly journals The development of methods for the determination of residues of the herbicide halauxifen-methyl in barley and rape

2018 ◽  
pp. 59-65 ◽  
Author(s):  
Mikhail F. Zayats ◽  
Sergey M. Leschev
Keyword(s):  
Aqueous Solution ◽  
Distribution Coefficients ◽  
Extraction Constant ◽  
Weak Base ◽  
Salting Out ◽  
Green Mass ◽  
Distribution Constants ◽  
Maximum Allowable Content ◽  
Hydrophobic Substance

Optimal conditions for the extraction of halauxifen-methyl from grain, straw and green mass of barley; seeds, oil and green mass of rape, as well as the conditions for the purification of extracts were selected on the basis of the distribution constants (P) and distribution coefficients (D) experimentally determined at a temperature of (20 ± 1) °C. At the first stage, acetonitrile, or acidified acetonitrile, or a mixture of water and acetonitrile were used to extract the pesticide. Halauxi fen-methyl was found to be a weakly hydrophobic substance and it exhibits the properties of a weak base in aqueous solutions. For the purification of plant material extracts hexane – 1 mol/L aqueous solution of hydrochloric acid and hexane – 10 % K2HPO4 aqueous solution were successfully used (to neutralize the acid and increase the extraction constant due to the salting out effect). The samples obtained after purification are sufficiently pure. So, the residual amounts of halauxifen-methyl can be determined by widespread liquid chromatography with diode array (ultraviolet) detection at the level, which is equal or lower to the maximum allowable content of herbicide in barley and rape.

scholarly journals INTERPHASE DISTRIBUTION OF SOME AMINO ACIDS IN EXTRACTION SYSTEMS BASED ON N-VINYLFORMAMIDE COPOLYMERS

2019 ◽  
Vol 62 (1) ◽  
pp. 4-10 ◽  
Author(s):  
Nadezhda Ya. Mokshina ◽  
Oksana A. Pakhomova ◽  
Gennadiy V. Shatalov ◽  
Irina I. Kosinova
Keyword(s):  
Amino Acids ◽  
Radical Copolymerization ◽  
Distribution Coefficients ◽  
Water Soluble ◽  
Separate Determination ◽  
Buffer Solution ◽  
Salting Out ◽  
Interphase Distribution ◽  
Degree Of Extraction

The extraction characteristics of amino acids and mono-amides of acids were studied using copolymers of N-vinylformamide with 1-vinyl- and 1-methacryloyl-3,5-dimethylpyrazole as extractants. Synthesis of water-soluble copolymers was carried out by radical copolymerization in dioxane with thermoinitiation with dinitro-azobisisomoic acid. The distribution coefficients and the degree of extraction of analytes for a single extraction in the presence of a salting out agent are calculated. To determine the representatives of amino acids, the method of capillary electrophoresis was used. The most effective extraction systems for the extraction of amino acids and monoamides of acids are proposed: the intrinsic viscosity of polymers, the concentration of polymer and analyte solution, the ratio of phase volumes, the ratio of the mole fractions of N-vinylformamide to 1-vinyl and 1-methacryloyl-3,5-dimethylpyrazole. The results of the most effective interfacial distribution of lysine between a water-salt solution and an extractant are presented, which is a copolymer of N-vinylformamide with 1-methacryloyl-3,5-dimethylpyrazole. The concentration of the copolymer and the ratio of the volumes of equilibrium phases at which the maximum degree of lysine extraction is reached are established. A copolymer of N-vinylformamide with 1-vinyl-3,5-dimethylpyrazole is used for simultaneous extraction of cystine, asparagine and glutamine. The established extraction characteristics allowed a successful separate determination of the amino acid cystine and monoamides (asparagine and glutamine) in a joint presence in an aqueous solution. When choosing the conditions for separate electrophoretic determination of amino acids, the optimal composition of the buffer solution, the type and concentration of the micelle was found. The dependence of the structure of the analytes on their interphase distribution was established, and the complexing power of the copolymers of N-vinylformamide with 1-vinyl- and 1-methacryloyl-3,5-dimethylpyrazole was revealed with respect to the representatives of amino acids. The extraction systems used on the basis of N-vinylformamide copolymers are distinguished by ecological and economic expediency, good metrological indices.

scholarly journals Extraction sample preparation for chromatographic determination of residual quantities of acidic penicillins in milk

2021 ◽  
Vol 57 (3) ◽  
pp. 286-293
Author(s):  
A. G. Polonevich ◽  
S. M. Leschev ◽  
A. I. Palianskikh ◽  
L. L. Belyshava
Keyword(s):  
Sample Preparation ◽  
Ammonium Sulfate ◽  
Chromatographic Determination ◽  
Distribution Coefficients ◽  
Penicillin G ◽  
Salting Out ◽  
Agent Based ◽  
Residual Content ◽  
Acid Type

The distribution of six acid-type penicillins (penicillin G, penicillin V, oxacillin, cloxacillin, nafcillin, dicloxacillin) in the extraction systems of chloroform–aqueous solutions of ammonium sulfate was studied. The reported distribution coefficients values of penicillins demonstrated the effectiveness of using ammonium sulfate as a salting-out agent. Based on the data obtained, a procedure for milk sample preparation was developed for the quantification of the residual content of six acid-type penicillins.

Atomic absorption determination of Hg (II), Cd (II), and As (III) in natural and waste water after preliminary group preconcentration

2019 ◽  
Vol 85 (2) ◽  
pp. 12-16
Author(s):  
I. V. Saunina ◽  
E. N. Gribanov ◽  
E. R. Oskotskaya
Keyword(s):  
Waste Water ◽  
Atomic Absorption ◽  
High Sensitivity ◽  
Distribution Coefficients ◽  
Neutral Medium ◽  
Atomic Absorption Determination ◽  
Absorption Determination ◽  
Relative Standard ◽  
Preliminary Group

The sorption of Hg (II), Cd (II), and As (III) by natural aluminosilicate is studied. It is shown that the mineral absorbs those toxicants in a rather wide pH range, quantitative extraction of analytes being achieved in a neutral or close to neutral medium (pH values range within 7.0 - 8.0; 6.3 - 7.5; 7.4 - 8.5 for Hg (II), As (III), and Cd (II), respectively). The effect of the time of phase contact on the degree of extraction of elements is shown. The sorption capacity of the mineral in optimal conditions of the medium acidity (0.06 mmol/g for mercury, 0.31 mmol/g for cadmium, and 0.52 mmol/g for arsenic) is determined. The distribution coefficients attain values of aboutnX 103-nX 104. A new combined method for determination of Hg (II), Cd (II), and As (III) in natural and waste water is developed and tested. The method consists in a preliminary group sorption concentration of the analytes by aluminosilicate, desorption of the analytes from the surface of the mineral and their subsequent atomic absorption determination. The correctness of the method is verified in analysis of spiked samples. The method is easy to use and exhibits high sensitivity, reproducibility and accuracy of analyte determination. The relative standard deviation does not exceed 0.13. Economic availability and possibility of using domestic sorption materials are the important advantages of the proposed procedure which can be used in the practice of laboratories monitoring the quality and safety of environmental objects.

Application of Silica Nanoparticles in the Determination of Herbicides in Environmental Water Samples Using Liquid Chromatography-Mass Spectroscopy

2020 ◽  
Vol 16 (5) ◽  
pp. 748-756
Author(s):  
Mir Waqas Alam ◽  
Tentu Nageswara Rao ◽  
Yarasani Prashanthi ◽  
Vourse Sridhar ◽  
Adil Alshoaibi ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Liquid Chromatography ◽  
Silica Nanoparticles ◽  
Solid Phase ◽  
Silica Nanoparticle ◽  
Environmental Water ◽  
Phase Extraction ◽  
Functionalized Nanoparticles ◽  
Supporting Material

Background: Herbicides are very beneficial in the crop yield with the aid of controlling weeds within the agriculture, but several herbicides are chronic in soil. Objective: In this study, nanoparticles and the packages of synthesized novel silica nanoparticles were studied for the preconcentration of herbicides. Methods: These nanoparticles prepared by the Stöber mechanism were purified and functionalized. Nanoparticles thus prepared successfully were used as supporting material for the preconcentration of residues of herbicides in the water. Results: Preconcentration was achieved by preparing the silica-based solid-phase-extraction cartridges. Nanoparticles used for this purpose were within the range of 50-250 nm. An SPE cartridge was prepared by packing 200 mg of silica nanoparticle in the empty cartridge of diameter 5.5 cm and length 0.6 cm in between PTFE frits. Aqueous solutions of 0.1 μg/ml of herbicides were prepared separately, and 10 ml of the solution was passed through the cartridge at the rate of 0.2 ml/min. After passing 10 ml volume of the aqueous solution, residues adsorbed on the cartridge were eluted using 2 ml of acetonitrile. The eluate was injected to determine the herbicide residue adsorbed on the SPE cartridge. Conclusion: In the study, it was found that greater than 90% of the herbicide residues were trapped on silica nanoparticle-based SPE cartridge. An analytical method was developed for the simultaneous determination of these herbicides. The residues were quantified by LC-MS/MS with ESI mode.

Equilibrium Sorptions in Heterogeneous Ion Exchange Membranes

1992 ◽  
Vol 57 (9) ◽  
pp. 1905-1914
Author(s):  
Miroslav Bleha ◽  
Věra Šumberová
Keyword(s):  
Experimental Data ◽  
Ion Exchange ◽  
Total Content ◽  
Distribution Coefficients ◽  
Exchange Capacity ◽  
Ion Exchange Membranes ◽  
Ion Exchange Capacity ◽  
Equilibrium Sorption ◽  
Inhomogeneity Factor

The equilibrium sorption of uni-univalent electrolytes (NaCl, KCl) in heterogeneous cation exchange membranes with various contents of the ion exchange component and in ion exchange membranes Ralex was investigated. Using experimental data which express the concentration dependence of equilibrium sorption, validity of the Donnan relation for the systems under investigation was tested and values of the Glueckauf inhomogeneity factor for Ralex membranes were determined. Determination of the equilibrium sorption allows the effect of the total content of internal water and of the ion-exchange capacity on the distribution coefficients of the electrolyte to be determined.

Enzymatic colorimetry of lecithin and sphingomyelin in aqueous solution.

1983 ◽  
Vol 29 (8) ◽  
pp. 1513-1517 ◽  
Author(s):  
M W McGowan ◽  
J D Artiss ◽  
B Zak
Keyword(s):  
Aqueous Solution ◽  
Hydrogen Peroxide ◽  
Amniotic Fluid ◽  
Enzymatic Reaction ◽  
Detergent Solution ◽  
Enzymatic Determination ◽  
Red Color ◽  
Hydrolysis Of ◽  
Zwitterionic Detergent

Abstract A procedure for the enzymatic determination of lecithin and sphingomyelin in aqueous solution is described. The phospholipids are first dissolved in chloroform:methanol (2:1 by vol), the solvent is evaporated, and the residue is redissolved in an aqueous zwitterionic detergent solution. The enzymatic reaction sequences of both assays involve hydrolysis of the phospholipids to produce choline, which is then oxidized to betaine, thus generating hydrogen peroxide. The hydrogen peroxide is subsequently utilized in the enzymatic coupling of 4-aminoantipyrine and sodium 2-hydroxy-3,5-dichlorobenzenesulfonate, an intensely red color being formed. The presence of a non-reacting phospholipid enhances the hydrolysis of the reacting phospholipid. Thus we added lecithin to the sphingomyelin standards and sphingomyelin to the lecithin standards. This precise procedure may be applicable to determination of lecithin and sphingomyelin in amniotic fluid.

Determination of the effective charge on muonium during its reaction in aqueous solution

1979 ◽  
Vol 6 (1-4) ◽  
pp. 409-412 ◽  
Author(s):  
Y. C. Jean ◽  
J. H. Brewer ◽  
D. G. Fleming ◽  
D. M. Garner ◽  
D. C. Walker
Keyword(s):  
Aqueous Solution ◽  
Effective Charge
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