I'm working with TGA (Thermogravimetric analysis) + DTA (Differential thermal analysis) of milk proteins on a STA2500 Regulus equipment by Netzch. I have two standards: one of B-Lactoglobulin and the other one of a-lactalbumin. I've worked with quite a few combinations of heat flow and sample size (mg) looking to obtain high quality thermograms (e.g. 10°K/min and 8 mg of sample, 8°K/min and 8 mg of sample, etc...).
In all cases, I'm obtaining a melting temperature (endothermic peak) for both samples at 72-73°C. This temperature would perhaps make sense for B-Lactoglobulin, but for a-lactalbumin temperatures in the order of 60-65°C have been reported. Furthermore, the thermogram for the two samples is practically the same.
Are there any suggestions on possible things I could be doing wrong?
Thanks in advance for your support.
If your information about two types of protein is correct. There are two likely possibilities from the start: 1) your samples are all the same, i.e. B-Lactoglobulin, make sure they are what they are as labelled, by other techniques; 2) if the other sample is a-lactalbumin as confirmed by other techniques, the conversion during the TGA/DTA tests could possibly be the cause, i.e. the latter converted to other materials/physical forms that has the same melt point of B-Lactoglobulin.
However, from the web, one can easily find that both have a denaturation temperature at ~70-73oC.
- Badges
- Science topic
- Similar topics
- Chemistry