Thermal activity monitoring

Isothermal storage tests (1ST), scanning or isothermal heat-flux micro-calorimeters, thermal activity monitor (TAM)—see Section 2.3.2.1,... 

A liquid flow microcalorimeter, the thermal activity monitor (TAM), is commercially available from ThermoMetric (formerly LKB/Bofors). This instrument consists of two glass or steel ampules with a volume of 3 to 4 cm3 (25 cm3 ampule available with a single detector), placed in a heat sink block. Recently, an injection-titration sample vessel was developed which acts as a microreactor. This vessel is provided with flow-in, flow-out, and titration lines, with a stirring device. The isothermal temperature around the heat sink is maintained by a controlled water bath. Each vessel holder, containing an ampoule, is in direct contact with a thermopile array, and the two arrays are joined in series so that their output voltages subtract. The two pairs of thermopile arrays are oppositely connected to obtain a differential output,... 

A comparison has been made between small scale test results and a field trial at a 17-ton scale for a solid compound [217]. The test results from a very sensitive calorimeter (Thermal Activity Monitor from ThermoMetric, Sweden) were substituted in a model, and the self-heating situation in bulk containers was predicted. The large-scale trial was carried out in a steel rectangular container lined with polyethylene. A control device was used to keep the container at a temperature of 40 to 45°C. Several thermocouples enabled monitoring of the temperature as a function of time in different places in the large container. 

TAM thermal activity monitor Differential, ideal flux Secondary reactions, storage stability 0.5-3 g 30 a 150°C 0.01... 

With the approach using isothermal thermograms, the different thermograms must be checked for consistency. In certain cases when the peaks are well separated, as for consecutive reactions, they may be treated individually and the heat release rates can be extrapolated separately, and used for the TMRai calculation. The reaction that is active at lower temperature will raise the temperature to a certain level where the second becomes active, and so on. So under adiabatic conditions, one reaction triggers the next as in a chain reaction. In certain cases, in particular for the assessment of stability at storage, it is recommended to use a more sensitive calorimetric method as, for example, Calvet calorimetry or the Thermal Activity Monitor (see Section 4.3), to determine heat release rates at lower temperatures and thus to allow a reliable extrapolation over a large temperature range. Complex reactions can also easily be handled with the iso-conversional method, as mentioned below. 

Fig. 5 Schematic diagram of an isoperibol calorimeter (top) and a thermal activity monitor (TAM) (bottom).

Differential thermal analysis is applied and the appearance or disappearance of one or more peaks is noted. Isothermal microcalorimetry can also be employed as well as a thermal activity monitor (TAM) technique. 

M.W. Whitmore and J.K. Wilberforce, Use of the Accelerating Rate Calorimeter and the Thermal Activity Monitor to Estimate Stability Temperatures, J. Loss Prev. Process Ind., 6-2, 95-101 (1993). 

The heat of adsorption of water vapor onto the surface of both polymorphs of the drug was measured under different RH conditions using an isothermal heat conduction microcalorimeter (Thermal Activity Monitor, TAM, Thermometric AB, Sweden). The integral heats of adsorption were measured using a TAM instrument fitted with a Thermometric RH perfusion ampoule (accessory Model 2255) adapted with Kalrez O-rings. The RH above the solid samples was controlled as originally described by Bakri (1993)... 

Adsorption enthalpies were measured in a Thermal Activator Monitor (TAM), an isothermal number 2277 microcalorimeter from LKB, Sweden. It contains a 25 ml stainless steel titration cell, fitted into a single detector measuring cylinder. The cell, with a reference ampoule, was especially designed for mixing liquids and adsorption from solution. For more details, and the execution of the measurements, see [6]. Basically, the heat evolved is measured by adding the surfactant solution to the kaolinite dispersion, where the heat of dilution is subtracted as the blank. In this way a plot q isiT) of the heat evolved as a function of the amount adsorbed F is obtained. 

Figure 1.15 Setup of a Thermal Activity Monitor, TAM (Thermometric/TA Instruments, Sweden/USA) right one of up to four calorimeters insertable into the thermostat...

Except for microcalorimetric titrations, readers are referred to the literature [14]. Microcalorimetric experiments at 298.15 K were carried out using the titration vessel of the 2277 Thermal Activity Monitor. The vessel was filled with 2.8 mL of a solution of p-te/t-butylcalix[4]eirene in benzonitrile (5 x 10 mol dm ) or in nitrobenzene (5 x 10" or 9 x 10 mol dm ). Triethylamine solutions in the appropriate solvent (concentration range 0.07-0.95 mol dm ) were injected (16 injections 0.015-0.025 mL for each run) from a 0.5 mL gas-tight Hamilton syringe, attached to a computer-operated syringe drive at 5 minute intervals, p-tert-Butylphenol solutions were 0.04 mol dm in both solvents. A dynamic correction... 

The thermal activity monitor (TAM TA Instruments, Delaware, USA) is also used for this type of measurement and employs the principle of breaking a glass ampoule in a solution under continuous mixing to measure the enthalpy change. 

Figure 2(A). A pictorial representation of the new flow module for the Thermometric 2277 Thermal Activity Monitor. The section labeled by A-A is illustrated in Figure 2(B).

---