By Professionals for Professionals

Mean Kinetic Temperature

Most of Signatrol’s range of temperature data loggers, running the Tempit-Pro software package, can be configured to compute and record Mean Kinetic Temperature ( MKT ). It is widely recognised that calculating Mean Kinetic Temperature gives a far more representative picture of the effects of temperature changes on sensitive materials such as pharmaceuticals and food products during storage and distribution. It can be shown that the ‘shelf life’ of sensitive materials is directly related to the Mean Kinetic Temperature.

Mean Kinetic Temperature ( MKT ),as defined by the United States Pharmacopoeia (USP), is a “single calculated temperature at which the total amount of degradation over a particular period is equal to the sum of the individual degradations that would occur at various temperatures” In non-technical terms, the mean kinetic temperature converts a variable temperature into an equivalent steady temperature, which is then used to determine the effect of the excursion on product quality. For example, Pharmacopoeia’s recommendations for "controlled room temperature," define that the temperature should be maintained between 15°C and 30°C, with a mean kinetic temperature less than 25°C. The calculation gives increased weighting to higher temperature excursions than normal arithmetic methods, recognising the accelerated rate of thermal degradation of materials at higher temperatures.

The SL151T temperature loggers are specifically designed to travel directly with goods and provide a detailed date and time temperature profile that can be used to highlight any problems. The data loggers are housed in a fully weld sealed crevice free, robust food grade polystyrene tags only 10mm thick and are the only loggers approved by the Royal Institute of Public Health.

The SL151T use a patented induction technique for set up and data down load. As a result there are no plugs, sockets or entries of any kind thereby avoiding potential ‘bug traps’ and ensuring total sealing. Powered by an internal battery, the units can be selected to log at intervals from 30 seconds up to 100 hours and have a measurement range from -30ºC to +60ºC. With an internal capacity of 24,576readings, the unit can keep recording for more than four years! The ‘delayed start’ feature can be set to coincide with the start of a particular travel schedule.

The mean kinetic temperature calculation is available to users of the Tempit Pro software. As Signatrol’s MD Brian Turner concludes: “ Users could calculate mean kinetic temperature themselves from the standard data using the Arrhenius equation. However it’s far quicker and safer to use our ready made calculator in the software. All the user has to do is enter the activation energy during set up (this can vary from 42-125 kJ/mol) and this can be determined by differential scanning calorimetry.

MKT = (-DH/R)/Ln{(SUM(exp(-DH/R*Tn))))/n}

where DH is the activation energy, R the universal Gas Constant (.0083144 kJ/molK), T is the temperature in Deg K, and n the total number of equal time periods over which data are collected., Ln the natural log, exp the natural log base and SUM is the total over n periods.

The following data loggers can be used to measure mean kinetic temperature:

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