A high sensitivity titration calorimeter using pyroelectric sensor (original) (raw)
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Industrial & Engineering Chemistry Research, 2003
We developed a new prototype reaction calorimeter with an integrated infrared-attenuated total reflection (IR-ATR) probe that has a sample volume of 45 mL and uses a metal block as an intermediate thermostat. Isothermal conditions are maintained using the power compensation principle. An additional heat balance using Peltier elements is implemented to compensate for changes of the reactor-sided heat-transfer coefficient and to circumvent corresponding calibration steps. The new calorimeter has been tested using the neutralization of NaOH with H 2 SO 4 and the hydrolysis of acetic anhydride. These experiments showed the precision of the new calorimeter and its capability to deal with fast and highly exo-or endothermic reactions. The kinetic parameters obtained from the IR and calorimetric measurements agree well with each other and with literature values. Even for the investigated simple reaction schemes, the IR-ATR probe provided additional information from what is obtained from the calorimetric signal alone.
A new general-purpose isothermal microcalorimeter for use at temperatures up to 200 °C
Thermochimica Acta, 2003
The design and some properties of a new general-purpose isothermal microcalorimeter are reported. The instrument is a twin thermopile heat conduction calorimeter, which is designed for use up to 200 • C. The calorimetric units and surrounding heat sink are suspended inside a hollow aluminium construction, which is thermostated. Above that unit a second thermostated block is positioned and the whole assembly is suspended inside a Dewar vessel. When the instrument is used at room temperature and below, the thermostated units are cooled by use of an insertion Peltier effect cooler. The instrument can be used with a wide range of different reaction vessels (diameter 14 mm). Baseline experiments have been conducted in the temperature range 15-200 • C. Typical values obtained during 10 h periods at 200 • C are ±3 and ±10 nW for the baseline drift and baseline fluctuations, respectively. The heat detection limit, determined by release of electrical energy, is about 2 J. Preliminary stability measurements have been conducted at 100 • C on samples of stabilised and non-stabilised polyamide film.
Organic Process Research & Development, 2001
To identify optimal operating conditions of a chemical process, knowledge on kinetic and thermodynamic parameters of the main reactions is needed. In particular in the fine chemical industry during the early phases of process development this knowledge is usually low. One reason is that only small amounts of substrate are available to perform the required calorimetric and analytical experiments. Therefore, we present in this paper a new prototype reaction calorimeter with a volume of 50 mL. Despite its small volume, the reaction calorimeter is combined with an IR-ATR probe to obtain augmented information from semibatch experiments under isothermal conditions. Furthermore, we present a new method to analyze the calorimetric measurements. The novelty of the approach is that all heat flows in the calorimeter are modeled together with the chemical reaction. For general reaction kinetics this reactor model cannot be solved analytically, and thus, numerical methods are applied for fitting the model parameters to the measurement data. In contrast to the traditional method of thermal conversion the rate constants and the heats of reaction are computed at the same time. The new reaction calorimeter and the new evaluation principle of the thermal signal were both tested using a singlestep second-order model reaction. Also the FT-IR data were evaluated by fitting the parameters in the reactor model numerically. The reaction parameters obtained with both measurement techniques are in good agreement with values published in the literature demonstrating the feasibility of the approach.
Influence of Dynamic Power Compensation in an Isothermal Titration Microcalorimeter
Analytical Chemistry, 1998
A theoretical analysis in Laplace's transformed domain based on a power balance represents a suitable model for an isothermal titration calorimeter with dynamic power compensation, designed and implemented in our laboratory. A rigorous calibration of the injection system and the calorimetric response was also made. Using electrically generated heat pulses, two different time constants have been determined from the calorimetric transfer function and assigned to the physical parts of the calorimeter. The same was done for a protein-ligand interaction. The binding of 2′-CMP to ribonuclease A at low and high ionic strengths was used to check the apparatus and the results were compared with those obtained by other authors (Wiseman, T.; Williston, S.; Brandts, J. F.; Lung-Nan, L. Anal. . In this case, the analysis showed a different time constant for the heat source. Independently of the nature of the heat source, the calorimetric time constants obtained while working under compensation are always smaller than those corresponding to a noncompensated system. The improvement of the calorimetric response introduced by dynamic power compensation is thus explained in terms of the reduction of the time constants characteristic of the calorimeter. This theoretical model can be used to predict the shape of the thermogram for any given reaction of either known or supposed thermodynamic parameters. Therefore, the calorimetric study is extended to the other nucleotides, 2′-UMP and 5′-dUMP, which have not hitherto been reported in the literature.
Titration Calorimetry Standards and the Precision of Isothermal Titration Calorimetry Data
2009
Current Isothermal Titration Calorimetry (ITC) data in the literature have relatively high errors in the measured enthalpies of protein-ligand binding reactions. There is a need for universal validation standards for titration calorimeters. Several inorganic salt co-precipitation and buffer protonation reactions have been suggested as possible enthalpy standards. The performances of several commercial calorimeters, including the VP-ITC, ITC200, and Nano ITC-III, were validated using these suggested standard reactions.
Elaboration of a basic calorimeter applied in the determination of the enthalpy of chemical reactions (Atena Editora), 2022
In thermodynamics, calorimetry studies the energies between the energy content between the products and reactant of an enthalpy reaction, which can occur with both compounds in liquid, solid and gaseous states. For the accomplishment of this work, products called acids and bases were used in their liquid form, resulting in a neutralization reaction. In this article, experimental data will be presented in order to demonstrate the enthalpy variations of an acid-base reaction from the construction of a low cost calorimeter, built with easily accessible materials, aiming to concentrate this energy, so that there was the lowest possible dissipation of it, seeking to reach the most plausible possible results compared to the parameters already pre-established for each reaction. We used an expanded polystyrene container (styrofoam), a conventional thermometer, the products and reagent, and at the end thermochemical equations were applied, such as the determination of the heat capacity of the measurement object and finally the appropriate transformations of the neutralization enthalpy calculations. , taking into account the possible interventions of the environment and the parameters not efficiently and accurately of the materials.
A versatile and high-precision solution—reaction isoperibol calorimeter
Journal of Thermal Analysis and Calorimetry, 2008
A new solution-reaction isoperibol calorimeter was developed to measure enthalpies of solution and reaction. A new system of sample cell was developed to avoid the breaking of glass ampoules, hence making the sample cell reusable. The system is suitable for measuring molar enthalpies of solid-liquid and liquid-liquid interactions at different temperatures. The reproducibility and accuracy of the apparatus were tested by measuring the enthalpy of solution of KCl in water at 298.15 K and the enthalpy of protonation of THAM in HCl (0.1 M) at 298.15 K. The results showed the uncertainty taken as the reproducibility was ±0.3% and the difference with the literature values was within ±0.5%.
Liquid and gas micro-calorimeters for (bio)chemical measurements
Sensors and Actuators A: Physical, 1994
Micro-calorimeters are offsetless and often highly selective chemical sensors that measure concentrations of substances in gases and liquids by detecting the heat of reaction. In this paper we present the results of a comprehensive study of the design, operation and performance of integrated-silicon and poly-silicon microcalorimeters for use with enzymatic and electropolymerized reactive coatings. 0924-4247/94/507.00 @ 1994 Elsevier Science S.A. AU rights reserved SSDI 0924-4247(93)00658-Q