scholarly journals DEVELOPMENT OF SULFENTRAZONE EXTRACTION PROCEDURE FROM COMMERCIAL HERBICIDE FORMULATION AND DETERMINATION OF ITS IONIZATION CONSTANT (pKa) BY POTENTIOMETRIC TITRATION

2018 ◽  
Vol 15 (29) ◽  
pp. 204-218
Author(s):  
S. L. A. OLIVEIRA ◽  
É. A SILVA ◽  
L. Z. PAULA ◽  
C. A. L. CARDOSO ◽  
G. J. ARRUDA ◽  
...  
Keyword(s):  
Thermal Analysis ◽  
Ionization Constant ◽  
Extraction Procedure ◽  
Scanning Calorimetry ◽  
Experimental Conditions ◽  
Degree Of Ionization ◽  
Potentiometric Titrations ◽  
Extraction And Purification ◽  
Pka Value

The herbicide sulfentrazone (SFZ) is widely used in soybean and sugarcane crops, although it is classified as very dangerous to the environment. To minimize barriers to the development of research with this herbicide due to the high cost of acquisition of its analytical standard and the availability of few distributors to acquire the standard in the country, a procedure of extraction and purification of SFZ was developed from a commercial herbicide formulation available in Brazil. Using the most suitable experimental conditions established for the extraction procedure, the SFZ content in the resulting solid after extraction and drying was 97.5% (m/m), which value was determined by acid-base potentiometric titrations. To characterize the solid obtained in this procedure, the material was studied by thermal analysis (thermogravimetry and differential scanning calorimetry) and Fourier transform infrared photoacoustic spectroscopy (FTIR-PAS) to confirm the presence of functional groups present in the SFZ molecule. Thermal analysis of the solid resulting from the extraction indicated processes of melting, thermal degradation and volatilization of the SFZ during its heating. By potentiometric titrations of the purified solid dissolved in water/acetonitrile (ACN) binary mixtures, it was possible to determine the ionization constant (pKa) of SFZ in water at 25.0ºC. By this study, extrapolated value of pKa in water is 6.45 obtained from the linear correlation of pKa versus molar ACN fraction plot. The value obtained at 25.0 °C by potentiometry in this study is quite close to the literature value of 6.56 determined at 20 °C by the spectrophotometric technique. However, the pKa value determined by potentiometric titrations of dilute solutions of the SFZ commercial formulations was much higher than that of 6.56, indicating that the degree of ionization of SFZ under herbicide application conditions can be quite distinct in the presence of possible adjuvants present in the commercial formulation of the herbicide.

Determination of Total and Free Water in Triple Superphosphate Fertilizers by Using Thermal Analysis

1985 ◽  
Vol 68 (4) ◽  
pp. 788-793
Author(s):  
Krystyna Kostyrko ◽  
Malgorzata Skoczylas ◽  
Andrzej Klee
Keyword(s):  
Thermal Analysis ◽  
Differential Scanning Calorimetry ◽  
Free Water ◽  
Total Water ◽  
Triple Superphosphate ◽  
Scanning Calorimetry ◽  
Thermal Methods ◽  
Dehydration Processes ◽  
Derivatographic Analysis

Abstract Thermal analysis methods were used to study dehydration of triple superphosphate. A redrying procedure followed by Q-derivatographic analysis (under quasiisobaric and quasiisothermal conditions) as well as differential scanning calorimetry (DSC) was applied. Attempts were made to establish the correct drying-oven temperature for determination of water content, i.e., the temperature at which free or total water is removed from the fertilizer. Thermal decomposition of monocalcium orthophosphate monohydrate, the major component of triple superphosphate, was studied and a model was advanced for the reactions that occur during decomposition of this salt. The free water was completely released when superphosphate was heated at a constant temperature of 85°C. The total water was entirely released at 160°C. At 150°C, the process of removing the water of crystallization from the orthophosphate was disturbed by other concomitant dehydration processes which result in irreversible decomposition of this salt. The results obtained indicate that the thermal methods of analysis used are complementary.

Determination of Ionization Constant (pKa) and Octanol–Water Partition Coefficient (Log P) of Cyclopiazonic Acid

2005 ◽  
Vol 88 (5) ◽  
pp. 1367-1370 ◽  
Author(s):  
Victor S Sobolev
Keyword(s):  
Partition Coefficient ◽  
Potentiometric Titration ◽  
Ionization Constant ◽  
Cyclopiazonic Acid ◽  
Log P ◽  
Experimental Conditions ◽  
Water Partition Coefficient

Abstract The ionization constant (pKa) and the octanol–water partition coefficient (log P) of the important mycotoxin cyclopiazonic acid (CPA) were determined by means of potentiometric titration, and the lipophilicity profile (log D) was calculated. Under the experimental conditions, pKa of CPA = 2.97 ± 0.09, log P = 3.83 ± 0.10, and log D at pH 7.4 = −0.58.

The Application of Differential Scanning Calorimetry to Thermal Analysis for Energetic Materials

2013 ◽  
Vol 423-426 ◽  
pp. 588-592
Author(s):  
Yong Kang Chen ◽  
Ming Hua Chen ◽  
Tao Zhang ◽  
Xiao Le Wu
Keyword(s):  
Thermal Stability ◽  
Thermal Analysis ◽  
Differential Scanning Calorimetry ◽  
Thermal Decomposition ◽  
Energetic Materials ◽  
Evaluation Research ◽  
Paper Briefly ◽  
Scanning Calorimetry ◽  
Main Components

Differential Scanning Calorimetry (DSC) is a common and useful method for thermal analysis. This paper briefly introduces the thermal decomposition characteristic determination of the main components of propellant by DSC assay and the applications of DSC in thermal stability and compatibility evaluation research of energetic materials.

In Situ Determination of Glass Transition Temperatures of Epoxy Adhesives in Structural Ceramic Assemblies

2011 ◽  
Vol 62 ◽  
pp. 107-116
Author(s):  
Valérie Nassiet ◽  
Bouchra Hassoune-Rhabbour ◽  
Yves Baziard
Keyword(s):  
Glass Transition ◽  
Thermomechanical Analysis ◽  
Epoxy Adhesive ◽  
Lap Joint ◽  
Scanning Calorimetry ◽  
Experimental Conditions ◽  
Single Lap Joint ◽  
Epoxy Adhesives

A method is described for measuring the glass transition temperature (Tg) of epoxy joints bonding ceramic (SiC) substrates. This method is based on the strain measure of a single-lap joint subjected to a temperature variation. The resulting displacement (d) is observed as a function of the temperature (T) by means of a contact strain gauge extensometer. Thus Tg value can be determined using (d-T) curves recorded. The influence of joint parameters (joint thickness and overlap length) and of other parameters such as the applied load and the surface state of substrates were studied for a structural epoxy adhesive showing different thermomechanical behaviours. The results show that it is possible, with appropriate experimental conditions, to measure Tg with this method and to find Tg values similar to those found by classical techniques such as the static thermomechanical analysis (TMA) and the differential scanning calorimetry (DSC). This method shows similarities with TMA, but it has the advantage to allow the thermomechanical analysis of adhesives without destructive sampling of joints.

Determination of Sodium Salvia Miltiorrhiza’s Optimal Analytical Conditions Detected by HPLC Method

2013 ◽  
Vol 446-447 ◽  
pp. 235-239
Author(s):  
Tao Wang
Keyword(s):  
Quality Control ◽  
Correlation Coefficient ◽  
Flow Rate ◽  
Salvia Miltiorrhiza ◽  
Hplc Method ◽  
Uv Detector ◽  
Experimental Conditions ◽  
Column Temperature ◽  
Extraction And Purification

The optimal analytical conditions of sodium salvia miltiorrhiza are detected by HPLC methods. SinoChrom ODS-BP C18 is selected as chromatographic column. The optimal experimental conditions under 280 nm wavelength UV detector include the column temperature: 28°C, ratio of methanol/water: 25/75 (v/v), and flow rate: 1.0ml/mol. The correlation coefficient is 0.9983, and RSD is 1.4%, when the linear range is 0.15~1.8μg/μL. In the experiment, the method is verified to be simple and reliable, and which can be used for the quality control in process of salvia miltiorrhiza extraction and purification.

scholarly journals On Experimental Thermal Analysis of Solid Materials

2014 ◽  
Vol 14 (6) ◽  
pp. 317-322 ◽  
Author(s):  
Pavel Koštial ◽  
Ivo Špička ◽  
Zora Jančikova ◽  
Jan Valiček ◽  
Marta Harničarova ◽  
...  
Keyword(s):  
Experimental Data ◽  
Thermal Conductivity ◽  
Thermal Analysis ◽  
Heat Capacity ◽  
Cooling Curve ◽  
Solid Materials ◽  
Experimental Conditions ◽  
Capacitance Model ◽  
Special Case

Abstract The paper is devoted to the presentation of a method for measurement of thermal conductivity k, specific heat capacity cp, and thermal diffusivity applying the lumped capacitance model (LCM) as a special case of Newton’s model of cooling. At the specific experimental conditions resulting from the theoretical analysis of the used model, we present a method for experimental determination of all three above mentioned thermal parameters for materials with different thermal transport properties. The input experimental data provide a cooling curve of the tested material. The evaluation of experimental data is realized by software, the fundamental features of which are presented here. The statistical analysis of experimental data was performed.

scholarly journals Synthesis and characterization of new complexes of some divalent transitional metals with isonicotinamido-4-chlorobenzalaldimine

2011 ◽  
Vol 76 (8) ◽  
pp. 1103-1115 ◽  
Author(s):  
Viorica Ababei ◽  
Angela Kriza ◽  
Cristian Andronescu ◽  
Magdalena Musuc
Keyword(s):  
Thermal Analysis ◽  
Magnetic Moments ◽  
Molar Conductivity ◽  
Azomethine Nitrogen ◽  
Scanning Calorimetry ◽  
Transitional Metals ◽  
Physico Chemical ◽  
Elemental Analyses

New complexes of isonicotinamido-4-chlorobenzalaldimine (INHCBA) with Cu(II), Co(II) and Cd(II), having formula of the type [M(INHCBA)(ac)2]?xH2O (M = Cu2+, x = 1, M = Co2+, x = 2, M = Cd2+, x = 0, ac = CH3COO-), and with Cu(II), Mn(II) and Zn(II), having formula of the type [M(INHCBA)2(H2O)2]SO4?xH2O (M = Cu2+, Mn2+, x = 2 and Zn2+ x = 2.5) were synthesized and characterized by analytical and physico-chemical techniques, i.e., elemental analyses, IR, UV-VIS- NIR and EPR spectroscopy as well as thermal analysis and the determination of the molar conductivity and magnetic moments. The thermal behaviour of complexes was studied by thermogravimetry (TG), differential thermal analysis (DTA) and differential scanning calorimetry (DSC). The ligand behaves as bidentate NO, being coordinated through the azomethine nitrogen and carbonylic oxygen. The heats of decomposition, ?H, associated with the exothermal effects, were also determined.

Antithrombin-mediated Inhibition of Factor Vlla-Tissue Factor Complex by the Synthetic Pentasaccharide Representing the Heparin Binding Site to Antithrombin

1996 ◽  
Vol 76 (01) ◽  
pp. 005-008 ◽  
Author(s):  
Jean Claude Lormeau ◽  
Jean Pascal Herault ◽  
Jean Marc Herbert
Keyword(s):  
Binding Site ◽  
Tissue Factor ◽  
Residual Activity ◽  
Coagulation Factors ◽  
Heparin Binding ◽  
Experimental Conditions ◽  
First Order ◽  
Heparin Binding Site ◽  
Coagulant Activity

SummaryWe examined the effect of the synthetic pentasaccharide representing the minimal binding site of heparin to antithrombin on the antithrombin-mediated inactivation of factor Vila bound to tissue factor. This effect was compared to the effect of unfractionated heparin. Using purified recombinant human coagulation factors and either a clotting or an amidolytic assay for the determination of the residual activity of factor Vila, we showed that the pentasaccharide was an efficient antithrombin-dependent inhibitor of the coagulant activity of tissue factor-factor Vila complex. In our experimental conditions, assuming a mean MW of 14,000 for heparin, the molar pseudo-first order rate constants for ATIII-mediated FVIIa inhibition by ATIII-binding heparin and by the synthetic pentasaccharide were found to be similar with respective values of 104,000 ± 10,500 min-1 and 112,000 ± 12,000 min-1 (mean ± s.e.m., n = 3)

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