Pressure perturbation calorimeter

The pressure perturbation calorimeter, a very special calorimeter accessory offered by MicroCal, measures differential heat change in a biopolymer solution, when the pressure above the solution is changed. This method is suitable for research on biopolymer solutions the interaction of biopolymers with the solvent is often highly sensitive to pressure changes. The measured heat, compared with that of the pure solvent, provides information about the interaction change with changed pressure. 

R. Ravindra, C. Royer, R. Winter, Pressure perturbation calorimetic studies of the solvation properties and the thermal unfolding of staphylococcal nuclease, Phys. Chem. Chem. Phys. 6(2004)1952-1961. 

Mention should be made here of the recently developed technique of pressure perturbation calorimetry (PPC), which measures the temperature-dependent volume change of a solute or colloidal particle in aqueous solution. PPC can also be used to detect thermotropic phase transitions in lipid model membranes and to characterize the accompanying volume changes and the kinetics of the phase transition. PPC essentially measures the heat change that results from small pressure changes at a constant temperature in a high-sensitivity isothermal calorimeter. For an excellent recent review on PPC as applied to lipid systems, the reader is referred to Heerklotz (19). 

DSCs designed for the measurement of extremely small amounts of samples must be sensitive and designed to accnrately and precisely control the temperature of the sample. Sensitivity is a byproduct of sample size, S/N, and baseline stability. Today s calorimeters incorporate new control capabilities that produce baseline stability that previously has not been available. This control also makes the instrument less susceptible to external environmental influences, and with the pressure control capabilities built into the newer models, the instruments are now appropriate for the study of volumetric properties (pressure perturbation) of biopolymers. 

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