Titration microcalorimeter using nanomolar quantities of reactants

A microcalorimeter has been developed for measuring the heat produced from small (10 μl) injections of 10 nanomoles of titrant into a 1-ml glass cell containing 100 nanomoles of sample. Typical heat measurements range from 30 to 300 μcal with reproducibility of 4 μcal. The small sample size is especially useful in studies of previous biological materials. The high sensitivity permits the use of low titrant concentrations (1 mM). The device is computer controlled allowing for automatic titration of preset injections. Heat compensation response times (half life) of 30 s are achieved with electronic feedback heater control. Both exothermic and endothermic titrations can be performed. Heat effects of single titration steps are given as computer output.