Influence of the Sample Weight, Butylated Hydroxytoluene - METTLER TOLEDO

Influence of the Sample Weight, Butylated Hydroxytoluene

SampleButylated hydroxytoluene

Butylated hydroxytoluene

 

Application

Inactive ingredient (antioxidant)

 

Conditions

Measuring cellDSC821e with IntraCooler

Pan: Aluminum 40 µl, hermetically sealed

Sample preparation: As received, no preparation

DSC measurement: Heating from 50 °C to 80 °C at 2.5 K/min

Atmosphere: Air, stationary environment, no flow

 

 

Interpretation

The curves show the melting peaks as a function of sample weight. As expected, the peaks in the original presentation (ordinate in mW) increase in height but also in width with increasing weight. Because of this the resolution decreases. In contrast, the normalized presentation shows that the lowest sample weight gives the highest peaks.

 

Evaluation

The onset temperature and heat of fusion of the peaks are determined. The mean values of a number of measurements are presented in the table.

Sample weightOnset, °CHeat of fusion ΔH, J/g
18 +/- 0.3 mg69.4 +/- 0.185.6, 84.7, 85.6
8.5 +/- 0.3 mg69.6 +/- 0.183.9, 84.5
4.0 +/- 0.3 mg69.5 +/- 0.182.6, 84.1, 83.6

 

Conclusion

The sample weight influences the shape of the melting peak. The time required for melting is longer for larger samples because a greater amount of heat has to be transferred. As a result of this, the peaks are shifted to higher temperature. For comparison purposes, the measurement of samples of similar weight is recommended. Samples that are too large are disadvantageous: the peaks become broad (lower resolution) and non-uniform melting leads to irregularly shaped peaks.

 

Influence of the Sample Weight, Butylated Hydroxytoluene | Thermal Analysis Application No. HB817 | Application published in METTLER TOLEDO TA Application Handbook Pharmaceuticals