There is no direct method for the detection of oxygen. The most commonly occurring elements in organic compounds are carbon, hydrogen, oxygen, nitrogen, sulphur and halogen elements. For detecting nitrogen, sulphur and halogens, we can use the sodium fusion test (Lassaigne’s test). Qualitative Analysis of Organic Compounds. Qualitative Analysis of Elements. There is no definite set procedure that can be applied overall to organic qualitative analysis. The analysis and identification of unknown organic compounds constitutes a very important aspect of experimental organic chemistry.