Introduction

Heat capacity is an integrated function of the THT Micro Reaction Calorimeter (μRC). Measurements require minimal setup and little or no analysis to obtain quick and reliable heat capacity data. Cp is determined by directly measuring the amount of heat required to shift the sample temperature. Water samples of several sizes were used to verify the μRC performance and demonstrate the instrument performance over a typical operational range. Experiment setup for Cp analysis is very simple. Precise knowledge of sample composition or expected values is not needed. Default settings are adequate for most experiments. Most measurements can be made by simply dropping in the sample and running.

Experimental

Typical experiments utilize a temperature shift of 1.0º C. Smaller shifts can be used for temperature sensitive materials. The temperature shift can be optimized to provide greater sensitivity, or greater dynamic range. Several different masses of water were placed in a standard μRC vial and allowed to equilibrate at 25° C. A small temperature step (usually in the order of 0.5-1°C) is then applied to the system and the heat is measured. The experiment is then repeated in reverse to verify the measurement. The results from each shift direction are averaged to give the final result. The experiment is conducted using 2 matched vials (pre weighed to reduce differences in mass affecting the results) and a measurement with an empty vial is conducted first to ensure that any small difference is accounted for.

Results

 The data shown overleaf highlight the ease of operation, accuracy and speed of measurement of heat capacity data. The wide range of masses used in these experiments highlights both the accuracy and wide applicability of this system. The data measured gave an overall heat capacity of 4.198J.g-1.°C-1 compared to the literature value of 4.182J.g-1.°C-1 giving an error of 0.4%. The repeatability of this measurement is 0.2% within each experiment and 1% between tests.

Discussion and Conclusions

Analysis of these measurements shows the excellent performance of the μRC Calorimeter. The average heat capacity measured is well within 1% of the published value over the whole of the mass range used. The speed of measurement and the ability of the instrument to measure non homogeneous materials with realistic sample sizes makes the μRC unique in its operation. The experimental protocol only requires the user to input the sample mass, experiment duration and the temperature shift required, no knowledge of material composition is required. This very simple approach makes this ideal for routine measurements of heat capacity for a wide range of operations.

 The THT Micro Reaction Calorimeter (µRC™) has a wide range of applications in the chemical, pharmaceutical and related fields. This brochure shows how using a microcalorimeter can help chemists and engineers in everyday tasks. 

Some of the applications detailed within this brochure include:

• Reaction Kinetics
• Process Development
• Scanning Calorimetry
• Thermal Stability
• Heat Capacity Measurement
• Adhesive Curing Reactions
• Waste Management
• End Point Determination
• Hazard Analysis

 All chemical, physical and biological reactions are accompanied by heat change. These reactions, though sometimes subtle, can be measured using calorimetry. This powerful analysis method works without modification of the sample or process. The THT Micro Reaction Calorimeter is based on power compensation technology making it faster in both signal response and temperature variation. Designed for maximum flexibility, the µRC has the capability to measure both kinetic and thermodynamic parameters in both rapid and slow reactions and in solids, liquids or gases. Measurements made by calorimetry are non-destructive and non-invasive making it valuable for initial analyses and for systems where other techniques fail. With the µRC there is minimal sample preparation and no limitation on the physical state of the material. Systems can be studied under ambient or modified environmental conditions.

Specification

• Baseline Noise: From 5μW
• Dynamic Range: 5μW to 600mW                                                      
• Temperature Range: -5°C to 170°C
• Standard Modes of Operation: Isothermal/Titration/ Scanning                                               
• Optional Modes: Pressure - pressurise cell up to 10bar                                                                                                           

  

•   Scanning Rate: Up to 2°C/min
• Isothermal Stability: +/- 0.0001°C over extended time period                                                        
• Cell Volume: 1.5 ml
• Cell Type: Removable glass vial
• Injection Volume: 1 to 250 μl
• Temperature Control: Peltier based (no external cooling)
• Stirring Speed: 0 - 400 rpm
• Measurement Principle: Power compensation
• Connection to PC: via USB cable
• Footprint (width x depth x height): 19 x 31 x 35 cm
• Certain other specifications may be possible by discussion