Search results for "Titration"

Ion pair recognition by ditopic crown ether based bis-urea and uranyl salophen receptors

2016

Differential regulation of hexameric and dodecameric hemocyanin from A. leptodactylus

2013

The oxygen binding properties of hemocyanins are regulated on a short time scale by effectors such as l-lactate, urate and protons, and on longer time scales by expression of the different types of subunits. For Astacus leptodactylus it was shown previously that acclimation to higher temperatures leads to increased levels of a 6-meric hemocyanin species, whereas at lower temperatures the 12-meric form prevails. Here we show that the temperature dependence of the two forms supports the idea, that the maintenance of high affinity towards oxygen is the driving force for the differential expression of these hemocyanins. Furthermore, the two different types of hemocyanin differ not only in the a…

Inorganic Mercury Sequestration by a Poly(ethylene imine) Dendrimer in Aqueous Solution

2015

The interaction of the G-2 poly(ethylene imine) dendrimer L, derived from ammonia as initiating core, with Hg(II) and HgCl4 2− was studied in aqueous solution by means of potentiometric (pH-metric) measurements. Speciation of these complex systems showed that L is able to form a wide variety of complexes including 1:1, 2:1, 3:1 and 3:2 metal-to-ligand species, of different protonation states, as well as the anion complexes ((H7L)HgCl4) 5+ and ((H8L)HgCl4) 6+ . The stability of the metal complexes is very high, making L an excellent sequestering agent for Hg(II), over a large pH range, and a promising ligand for the preparation of functionalized activated carbons to be employed in the remedi…

Opioid-induced hyperalgesia after rapid titration with intravenous morphine: Switching and re-titration to intravenous methadone.

2012

Rapid titration with intravenous morphine (IV-MO) provides fast and efficient pain relief in cancer patients with severe-excruciating pain. However, some patients, after an initially favourable response, can develop an hyperexcitated state unrelieved or worsened by further dose increments.Eighty-one patients admitted on emergency basis titrated with IV-MO were assessed.12 patients were unsuccessfully titrated with IV-MO. Switching to intravenous methadone (IV-ME) and titrating the doses proved to be successfully.In escalating opioid doses rapidly a recognition of the development of hyperalgesia should be suspected. Increasing doses of opioids may stimulate rather than inhibiting the central…

Complex technological and biological research of solutions for peritoneal dialysis

2018

Objective : The purpose of our work was to conduct technological, analytical, and biological investigations and stability studies of peritoneal dialysis (PD) solutions containing glucose and sodium lactate in single-chamber containers. Methods : Different formulations of PD solutions were prepared and sterilized at a temperature of 121 °C during 15 m. UV-spectrophotometric determination was performed using purified water as a blank. The spectra of the solutions were run in the range of 220 to 400 nm for the identification of an absorption maximum (λ max ) and measuring the absorbance at 228-230 nm and λ max before and after heat sterilization. λ max of the most PD solutions after sterilizat…

High-affinity and selective detection of pyrophosphate in water by a resorcinarene salt receptor

2017

N-Alkyl ammonium resorcinarenes selectively bind pyrophosphate in pure water with an exceptionally high binding constant of up to 1.60 × 107 M–1, three orders of magnitude higher than ATP.

Polysubstituted ferrocenes as tunable redox mediators

2018

A series of four ferrocenyl ester compounds, 1-methoxycarbonyl- (1), 1,1’-bis(methoxycarbonyl)- (2), 1,1’,3-tris(methoxycarbonyl)- (3) and 1,1’,3,3’-tetrakis(methoxycarbonyl)ferrocene (4), has been studied with respect to their potential use as redox mediators. The impact of the number and position of ester groups present in 1–4 on the electrochemical potential E1/2 is correlated with the sum of Hammett constants. The 1/1+–4/4+ redox couples are chemically stable under the conditions of electrolysis as demonstrated by IR and UV–vis spectroelectrochemical methods. The energies of the C=O stretching vibrations of the ester moieties and the energies of the UV–vis absorptions of 1–4 and 1+–4+ c…

Thermodynamic and spectroscopic study of the binding of dimethyltin(IV) by citrate at 25°C

2006

Thermodynamic (potentiometric and calorimetric) and spectroscopic ( 1 H NMR, 119 Sn Mossbauer) studies were performed in aqueous solution in order to characterize the interaction of dimethyltin(IV) cation with citrate ligand. Six species {(CH 3 ) 2 Sn(cit) - ; [(CH 3 ) 2 Sn] 2 (cit) 2 2- ; (CH 3 ) 2 Sn(cit)H 0 ; (CH 3 ) 2 Sn(cit)OH 2- ; [(CH 3 ) 2 Sn] 2 (cit)OH 0 ; [(CH 3 ) 2 Sn] 2 (cit)(OH) 2 - } were found. All the species formed in this system are quite stable and formation percentages are fairly high. For example, at pH = 7.5 and C (CH3)2Sn = C cit = 10 mmol l -1 , E% for [(CH 3 ) 2 Sn] 2 (cit)(OH) 2 - and (CH 3 ) 2 Sn(cit)OH 2- species reaches 65%. Overall thermodynamic parameters obta…

Calcium mediated polyelectrolyte adsorption on like-charged surfaces.

2011

International audience; Monte Carlo simulations within the primitive model of calcium-mediated adsorption of linear and comb polyelectrolytes onto like-charged surfaces are described, focusing on the effect of calcium and polyion concentrations as well as on the ion pairing between polymers and calcium ions. We use a combination of Monte Carlo simulations and experimental data from titration and calcium binding to quantify the ion pairing. The polymer adsorption is shown to occur as a result of surface overcharging by Ca2+ and ion pairing between charged monomers and Ca2+. In agreement with experimental observations, the simulations predict that the polymer adsorption isotherm goes through …

Implementation of Computer Assisted Experimental Work in Analytical Chemistry Laboratory Teaching

2019

[EN] Computer-Assisted Experimental Work (CAEW) consists in the incorporation of computer-connected apparatus in the laboratory. This is a new insight into teaching of Classical Analytical Chemistry, wherein the experiments are usually manually conducted. However, it does not represent a complete break with traditional methodology, as the design and goal of the experiment are essentially the same. In this work, we present the implementation of CAEW to a practical included in the Laboratory part of “Analytical Chemistry IV”, taught at the fourth academic year of the Degree in Chemistry: “Potentiometric titration of a mixture of iodure and chlorure with silver”. Three couples of students used…