I am using Mettler Toledo DSC 2 to find cp of In/Zn with sapphire and direct methods.
The DSC is calibrated with both In and Zn and is within the specifications. However when I try to find cp values, those are way off from the literature values. All measurements were made on 40 ul Aluminum pans with pierced lids. Temp range 5 C to 115 C with 10 C/minute heating rate. For sapphire method, I included two isotherms at 5 C and 115 C respectively. Mass of sapphire was 28.05 mg, Zn 2.90 mg, In 6.59 mg.
Please advise what is wrong with my measurements
Thank you.
Thank you Adeyinka. Considering both the heat flow and the mass normalized, what do you think can make the cp values different? The values shouldn't be way off from the expected even the sample size is slightly smaller (I might be wrong). I am going to give it a try and will share the outcome with you.
Your sample might not be melting all at once or slightly decomposing after melting. Try with a smaller sample size and see what happens but make sure you recalibrate your equipment first.
should I calibrate with new samples? I have 3.96 mg of Zinc and 4.87 mg of indium. I have standard calibration samples sitting inside the tray which are Zinc 2.90 mg, Indium 6.59 mg. Thank you for your help
Still didn't work for me (please see the attached).. The literature value for Zn is 0.382 J/g/C and Indium is 0.231 J/g/C. I did calibration again and DSC was within specifications. Have you ever experienced something like this?
Thank you. I will be speaking with MT Technical support and will share if something is positive and benifits the community.
Thanks for your time.
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