Pressure-Modulated Differential Scanning Calorimetry. An Approach to the Continuous, Simultaneous Determination of Heat Capacities and Expansion Coefficients

Abstract

A new method is described that permits the continuous and synchronous determination of heat capacity and expansibility data. We refer to it as pressure-modulated differential scanning calorimetry (PMDSC), as it involves a standard DSC temperature scan and superimposes on it a pressure modulation of preselected format. The power of the method is demonstrated using salt solutions for which the most accurate heat capacity and expansibility data exist in the literature. As the PMDSC measurements could reproduce the parameters with high accuracy and precision, we applied the method also to an aqueous suspension of multilamellar DSPC vesicles for which no expansibility data had been reported previously for the transition region. Excellent agreement was obtained between data from PMDSC and values from independent direct differential scanning densimetry measurements. The basic theoretical background of the method when using sawtooth-like pressure ramps is given under Supporting Information, and a complete statistical thermodynamic derivation of the general equations is presented in the accompanying paper.

CHAPTER 18. Molar Volumes of Electrolyte Solutions

“…An interesting recent development is the technique known as pressure perturbation calorimetry, which provides a quick and convenient way of obtaining precise expansibilities of electrolyte solutions. 26 Similar techniques are discussed in Chapter 14.…”

Probing volumetric properties of biomolecular systems by pressure perturbation calorimetry (PPC) – The effects of hydration, cosolvents and crowding

“…This calorimeter has basically the same architecture as a power-compensation differential scanning calorimeter (DSC), but measures the heat flow into or out of a sample upon small isothermal pressure changes (of typically ±5 bar). The method can be applied to study the coefficient of thermal expansion, a, and relative volume changes, DV/V, of aqueous solutions and dispersions of chemical and biochemical systems, including amino acids, proteins, DNA and phospholipid vesicles, micellar systems, and polymers [1][2][3][4][5][6][7][8][9][10][11].…”

DNA hydration studied by pressure perturbation scanning microcalorimetry

“…Pressure perturbation differential scanning calorimetry (PP‐DSC) is a new technique which permits determination of the thermal expansion coefficients of solute molecules in their dilute solution and thus estimates temperature‐induced changes of the partial volume of the solutes 1–4. A number of laboratories have used PP‐DSC for studying aqueous solutions of various low molecular weight compounds, lipids, and proteins 5–9.…”