So what is your sample? Without this information any diagnosis is impossible. Post the TGA plot.

It is a metal organic framework, you can have a look,, synthesized by zinc 2 methylimidazole and chloroauric acid

The next step is to carry out TGA's on the individual components. Then compare. You'll be able to see or surmise what decomposition routes are associated with each step. Be aware the gold will leave a stain in the pan, so I assume you're using disposable pans.

I suspect you'll have a sequence involving moisture loss (HAuCl4.xH20), followed by decomposition steps of the organic and then the chloroauric acid to end up with gold metal. The proportions of materials are important.

Thankyou for your answer

well not exactly, but its true,

to be more precise i synthesized ZIF-8 MOF and then reduced gold ions formed by chloroauric acid to gold nano particles which I am assuming to be succesfully encapsulated in the pores of ZIF-8 with really small size. so according to that what I analyzed was that first the oirganic part decomposes but not all.

but technically all the organic part should decompose. so why does this happen if I am right? why doesnot the whole organic part decomposes at the same point?

Thanks

Why would you expect the organic to decompose at the same point rather than over a range of temperatures? Do you have a diffusion-controlled or a chemically-controlled decomposition?

Because 2-methylimidazole acts as a link between the zinc vertice. they are connected by the coordination bond which have a moderate strength. so depending on the bond strength i think first the bond breaks. then the organic part decomposes. and normally the organic part has lower boiling point but because of the bonding with Zinc it needs high temperature. Is it right?? also here the gold nanoparticle is not bondded but only encapsulated. so why does the mass loss goes to high temperature?

well it should be chemically controlled as far as i know.