This is true, however other molecules will have similar melting points to different AAS compunds. While it is a good place to start, of course it is best to send oil or powder to a lab.There are ways how you can isolate powder from the oil if you wanted to perform melting tests on the solid to determine its purity.
But I agree this is a good place to start, and with the right chemicals and a kitchen it is verrry easy.