A numerical method for the determination of first-order kinetics relaxation time spectra

The speciation of Al-OH complexes in terms of Ala, Alb and Alc could be achieved by traditional ferron assay and Alb is generally considered as Al13, however, the inherent correlation between them remains an enigma. This paper presents a modified ferron assay to get precise determination of Al13 using nonlinear least squares analysis, and to clarify the correlation between Alb and Al13. Two parallel reactions conforming to pseudo-first-order kinetics can simulate the complicate reactions between polynuclear complexes and ferron successfully. Four types of experimental kinetic constant (k value) of Al-OH complexes can be observed by this method when investigating three typical aluminium solutions. Comparing with the results of 27Al NMR, the species with moderate kinetics around 0.001 s−1 can be confirmed to resemble to Al13 polycation. The other types of kinetics are also well-regulated in partially neutralized aluminium solutions with various OH/Al ratios (b values) in the range 0 ∼ 2.5. It would provide potential means to trace the in-situ formation of Al13 in dilute solutions such as coagulation with Al-based coagulants

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Effect of thiol oxidation and thiol export from erythrocytes on determination of redox status of homocysteine and other thiols in plasma from healthy subjects and patients with cerebral infarction

Clinical Chemistry ◽

10.1093/clinchem/41.3.361 ◽

1995 ◽

Vol 41 (3) ◽

pp. 361-366 ◽

Cited By ~ 79

Author(s):

A Andersson ◽

A Lindgren ◽

B Hultberg

Keyword(s):

Cerebral Infarction ◽

Healthy Subjects ◽

Redox Status ◽

Reduced Form ◽

Temperature Dependent ◽

First Order ◽

First Order Kinetics ◽

Before And After ◽

Reduced Forms

Abstract Changes in concentration of reduced and oxidized low-M(r) thiols were measured in blood and plasma before and after the separation of blood cells. If centrifugation of blood was postponed, the reduced form of homocysteine in plasma increased with time at 22 degrees C; in contrast, the concentrations of other reduced thiols (cysteine, glutathione, and cysteinylglycine) decreased. In plasma the reduced forms of all thiols disappeared at a rate that followed first-order kinetics. The rates of disappearance ("half-lives") were temperature-dependent; they were about the same for glutathione and homocysteine (11.7 and 14.3 min, respectively, at 22 degrees C) and somewhat higher for cysteinylglycine and cysteine. After establishing proper sampling conditions for reduced thiols, we measured this thiol fraction as well as free (non-protein-bound) and total thiols in 10 reference subjects and 19 patients with cerebral infarction. Mild but significant hyperhomocysteinemia involving total and free homocysteine (but not reduced homocysteine) was found in the patients.

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The Effect of Tb and Sm Ions on the Photochromic Behavior of Two Spiropyrans of Benzoxazine Series in Solution

Research Letters in Physical Chemistry ◽

10.1155/2008/314898 ◽

2008 ◽

Vol 2008 ◽

pp. 1-4 ◽

Cited By ~ 4

Author(s):

Esam Bakeir ◽

G. M. Attia ◽

Maria Lukyanova ◽

Boris Lukyanov ◽

M. S. A. Abdel-Mottaleb

Keyword(s):

Relaxation Time ◽

Ring Opening ◽

Bond Cleavage ◽

Lanthanide Ions ◽

Photochromic Behavior ◽

First Order ◽

Color Development ◽

First Order Kinetics ◽

Thermal Bleaching ◽

Color Enhancement

The photochromism of [7′-hydroxy-8′-formyl-3-methyl-4-oxospiro[1,3-benzoxazin-2,2′-[2H-1]benzopyran],SP(I),[7′-hydroxy-8′-formyl-3-benzyl-4-oxospiro[1,3-benzoxazin-2,2′-[2H-1]benzopyran] SP(II) and their coordination with Tb3+and Sm3+ ions have been studied in DMF. UV/vis induced-color development due to heterolytic bond cleavage of SP(I) and SP(II) is greatly influenced by complexation with the lanthanide ions. The irradiation-induced color enhancement due to ring opening and thermal decoloration of the open forms of SP(I), SP(II) follows first-order kinetics. Physical characteristics of the studied systems such as colorability and relaxation time of thermal bleaching parameters were determined. Moreover, light-energy transfer-induced luminescence of lanthanide ions via coordination with the two spirobenzoxazines was monitored.

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A general expression for coupled enzyme assays of hysteretic enzymes

Biochemical Journal ◽

10.1042/bj2200173 ◽

1984 ◽

Vol 220 (1) ◽

pp. 173-178 ◽

Cited By ~ 1

Author(s):

I E Woodrow ◽

G A Manson

Keyword(s):

Relaxation Time ◽

General Expression ◽

Accurate Determination ◽

Relaxation Times ◽

Rate Equations ◽

Enzyme Assays ◽

General Description ◽

First Order ◽

Low Concentrations

A general description of a system consisting of a hysteretic enzyme and a series of coupling enzymes is presented. The chloroplast enzyme sedoheptulose-1,7-bisphosphatase and a sequence of three coupling enzymes is used as an example. An analysis using first-order rate equations for the coupling enzymes shows that the observed relaxation time of the system is the sum of the relaxation times of the coupling enzymes and that of the hysteretic enzyme. The behaviour of a system with relatively low concentrations of coupling enzymes, where the first-order assumption is not valid, is analysed by computer stimulation. Several methods for the accurate determination of the relaxation time of the hysteretic enzyme are discussed.

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Mineralization of sulfonamides from wastewater using ozone-based systems

Water Science & Technology ◽

10.2166/wst.2021.325 ◽

2021 ◽

Author(s):

T. H. Ho ◽

C. H. Wu ◽

T. Y. Han ◽

W. J. Syu

Keyword(s):

Steric Hindrance ◽

Radical Addition ◽

The Novel ◽

Mineralization Rate ◽

First Order ◽

First Order Kinetics ◽

Pseudo First Order ◽

Uv Ozone ◽

Heterocyclic Group

Abstract Ozone, UV/ozone, ozone/persulfate (PS) and UV/ozone/PS systems were used to mineralize sulfonamides. Sulfadiazine (SDZ), sulfamerazine (SMR) and sulfamethazine (SMZ) were the target compounds. The novel contribution of this study is its determination of the effects of PS addition, sulfonamide structure, pH and salinity on sulfonamide mineralization in ozone-based systems. The mineralization rate of sulfonamides satisfied pseudo-first-order kinetics. The SMZ mineralization rate constant in ozone, UV/ozone, ozone/PS and UV/ozone/PS systems at pH 5 were 0.0058; 0.0101; 0.0069 and 0.0802 min−1, respectively, and those at pH 7 were 0.0075; 0.0116; 0.0083 and 0.0873 min−1, respectively. The increase in the number of methyl-substituents in the heterocyclic group of SMZ and the corresponding increase in the steric hindrance of radical addition, reduced mineralization rates below those of SMR and SDZ. The addition of PS promoted sulfonamide mineralization in the ozone-based systems; conversely, salinity inhibited sulfonamide mineralization.

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Nonlinear regression least‐squares method for determining relaxation time spectra for processes with first‐order kinetics

Journal of Applied Physics ◽

10.1063/1.332390 ◽

1983 ◽

Vol 54 (5) ◽

pp. 2137-2146 ◽

Cited By ~ 50

Author(s):

J. R. Cost

Keyword(s):

Relaxation Time ◽

Least Squares ◽

Nonlinear Regression ◽

Least Squares Method ◽

First Order ◽

First Order Kinetics

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ESTUDO DE ESTABILIDADE DO FOSFATO DISSÓDICO DE PREDNISOLONA EM CONDIÇÕES DE ESTRESSE OXIDATIVO E TÉRMICO, EM FORMULAÇÃO ORAL

Eclética Química Journal ◽

10.26850/1678-4618eqj.v35.4.2010.p09-15 ◽

2018 ◽

Vol 35 (4) ◽

pp. 09

Author(s):

Cleber Antonio Lindino ◽

Marcia Lina Mitsui ◽

Rodolfo Ortiguara ◽

Daiane Felin ◽

Mauricio Ferreira Da Rosa ◽

...

Keyword(s):

High Performance ◽

Dosage Form ◽

Degradation Products ◽

Degradation Process ◽

Oral Solution ◽

Form Solution ◽

Oral Dosage ◽

First Order ◽

First Order Kinetics

This work was to investigate the process of degradation of the drug Prednisolone Sodium Phosphate (FSP) in oral solution dosage form through the degradation experiments, evaluating the parameters in accordance with Resolution 899/2003 ANVISA and the degradation process of the drug. The method by high performance liquid chromatography (HPLC) developed for the determination of the drug was validated to demonstrate its applicability as an indicator of stability, ensuring reliability. After the method be validated to study the degradation of the drug, it was shown that drastic conditions of oxidative stress (H O 30%) and 2 2 temperature 60°C, the degradation of the drug is dependent on its concentration (first order kinetics). The results were satisfactory, showing that this method is suitable to investigate the formation of degradation products in oral dosage form solution

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Determination of Ozone or Hypochlorite in Waters Based on Digital Images Analysis Using Same Reagent

Journal of the Brazilian Chemical Society ◽

10.21577/0103-5053.20210106 ◽

2021 ◽

Author(s):

Lorrayne Zampier ◽

André Fernando de Oliveira ◽

Fernanda Heleno ◽

Maria Eliana de Queiroz ◽

Antônio Augusto Neves ◽

...

Keyword(s):

Digital Image Analysis ◽

Digital Images ◽

First Order ◽

Figures Of Merit ◽

Malachite Green Dye ◽

First Order Kinetics ◽

The Subject ◽

Different Response ◽

Analytical Resolution

Ozone and hypochlorite are used for the disinfection of water and is essential to monitor these. In this paper, methods based on digital images were developed to determine these analytes in waters using the malachite green dye. The oxidation of the reagent with ozone was very fast and with hypochlorite occurred in 10 min in pseudo-first-order kinetics. New software called ICCA was developed for the capture and processing of red, green and blue (RGB) data, which is planned for digital image analysis. In addition, the recently proposed parameters analytical resolution and N9 were used to define some study conditions. An evaluation of different response functions and white correction of the webcam were done, having thrown some light on the subject to this theme. Their optimization showed a linear range from 0.6 mg L-1 to 5.0/6.0 mg L-1 (O3/Cl, respectively). The figures of merit were similar for both. The methods were validated and the recoveries achieved were between 85.0 and 96.0% (ozone) and 101.0 and 119.0% (hypochlorite).

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A KINETIC ANALYSIS OF THE RENIN-ANGIOTONIN PRESSOR SYSTEM AND THE STANDARDIZATION OF THE ENZYMES RENIN AND ANGIOTONASE

Journal of Experimental Medicine ◽

10.1084/jem.78.5.367 ◽

1943 ◽

Vol 78 (5) ◽

pp. 367-386 ◽

Cited By ~ 9

Author(s):

Albert A. Plentl ◽

Irvine H. Page

Keyword(s):

Pressor Response ◽

Accurate Method ◽

Enzyme Concentration ◽

Renin Substrate ◽

First Order ◽

First Order Kinetics ◽

Consecutive Reactions ◽

Slow Decline ◽

Reaction Constant

The physicochemical background of the renal vasporessor system (renin-renin-substrate, angiotinin, angiotonase) is given. The formation and destruction of angiotonin is shown to consist of two consecutive reactions, both of which follow the laws of first order kinetics. Each reaction was studied separately and its reaction constant found to be proportional to the enzyme concentration. Hence these constants should be used to express the activity of the enzymes, renin and angiotonase. The over-all reaction of a mixture of renin and angiotonase such as occurs in kidney extracts with the α-globulin fraction of serum, viz., rapid increase followed by a slow decline in angiotonin concentration, was found experimentally to correspond closely to the theoretical values calculated for such a reaction. The curve obtained also satisfyingly explains the characteristic pressor response to the intravenous injection of renin. An accurate method for the determination of renin in the presence of angiotonase is presented.

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