The heat treatment of the graphene oxide/ thiourea mixture was done by the tube furnace equipped with an argon inlet. The graphene oxide/ thiourea sample was characterized by UV–visible spectrometry, Thermogravimetric analysis, Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. The UV–vis absorption spectra of graphene oxide was shown the characteristic absorbance of graphene oxide, and the Fourier transform infrared spectra showed carboxylic acid group and thiocyanate on the surface of graphene oxide/thiourea. The deconvolution of X-ray photoelectron spectra showed the sulfur and nitrogen on the surface of graphene oxide. The peak area, the percent of carbon, oxygen, nitrogen, and sulfur of modified graphene oxide based on Scofield’s relative sensitivity factor (RSF), was 73, 16, 7, and 4, respectively. The fluorescence measurements of the modified graphene oxide suspension in the different pH were investigated. The alkaline solution showed the most emission intensity. The sample was shown good interaction with uric acid in the alkaline solution compared to other substances, including thiamin, nicotinamide, urea, ascorbic acid, glucose, and lauric acid, based on fluorescence spectroscopy
