An Isothermal Titration Microcalorimeter

Abstract

An isothermal titration microcalorimeter having a volume of 4 ml and capable of temperature control to ± 2 × 10−5 °C is described. Major components include a constant temperature water bath controlled to ± 3 × 10−4 °C, a platinum reaction vessel, and an isothermal control circuit consisting of constant Peltier thermoelectric cooling and variable Joule heating controlled by a thermistor in an ac Wheatstone bridge circuit. The calorimeter was tested by measuring the heat of ionization of water and was found to produce data accurate to ±0.1% for this system. The instrument is ideally suited for measuring heats where small samples are used such as in the investigation of many biological systems.

Excess enthalpies of (carbon dioxide + propylene carbonate orN-methyl-ε-caprolactam or 1-formyl piperidine) at the temperatures 298.15 K and 308.15 K and pressures from 7.5 MPa to 12.5 MPa

“…The apparatus and solvent-delivery system are very similar in design to those described by Christensen and coworkers. (6,7) The water bath of the calorimeter (volume: 55 dm 3 ) provided temperature control of 20.0006 K. Fluids studied were injected into the flow cell by means of two Isco 260D high-pressure pumps operated in a steady-state (fixed-composition) mode. The total volumetric flow rate was 0.007 cm 3 ·s −1 or 0.010 cm 3 ·s −1 depending on the magnitude of the measured signal.…”

Calorimetric Methods for the Study of Adsorption of Surfactants at Solid/Solution Interfaces

“…In isotherm power compensation calorimetry [3][4][5], the inactive reference cell is maintained throughout at the temperature of the thermostat, while in the active sample cell the heat of the thermal event (adsorption) is compensated internally by Peltier cooling (if exothermic) or by Joule heating (if endothermic). To this end, the temperature of the sample is continuously monitored relative to that of the reference, and every small deviation is corrected by means of a closed-loop control system (Fig.…”

Microflow calorimeter design for heats of mixing

“…The best types are capable of excellent accuracy, and among the best known are those of Larkin and McClashan (1961), Mrazekand Van Ness (1961), Winterhalter and Van Ness (1966), Christensen et al (1968Christensen et al ( , 1973, and their subsequent variants. Batch-type instruments do not lend themselves readily to automation and, unless carefully designed and operated, are subject to several possible sources of error.…”