EN
Pretreatment and analysis of urea and uric acid in body fluids and those of newly identified toxic compounds in dental material are described. Urea is a major uremic toxin. The accumulation of urea in blood may promote serious uremia syndrome if not regularly removed. Thus, an accurate analysis of blood urea is required for precise diagnosis. There have not been reported so far for differential analysis of free blood urea from bound urea as well as urea from endogenous ammonium. The author found the simplest differential method of urea and endogenous ammonium analysis in blood using a strong cation exchange resin column. For pretreatment of blood urea, solid phase extraction and dialysis were compared. The solid phase extraction method was found to be superior to dialysis in terms of recovery rate. Separation efficiency and reproducibility of blood urea determination using HPLC and MECC were also compared. Identification of newly toxic compounds in dental material, was carried out by LC-MS-MS and determination to saliva was by HPLC combined with SPE.