title: Evaluation of 2-iminoimidazolidin-4-one and thymine as respective internal standards for normal-phase and reversed-phase high-performance liquid chromatographic determination of creatinine in human serum.
abstract: We evaluated two internal standards for HPLC determination of creatinine in human serum after ultrafiltration: 2-iminoimidazolidin-4-one for normal-phase HPLC on aluminium oxide, and thymine for C18 reversed-phase HPLC. Detection of 2-iminoimidazolidin-4-one was done at the same wavelength as that used for creatinine, i.e. 240 nm. For thymine, the wavelength was switched to 280 nm. The suitability of the selected compounds to serve as an internal standard in the described measurement procedures, including ultrafiltration of serum, was evaluated from the precision and accuracy obtained. The method based on normal-phase HPLC with 2-iminoimidazolidin-4-one showed an imprecision expressed as R.S.D. ranging from 0.8 to 3.4% (mean: 2.1%) and an inaccuracy, calculated from the deviations from target values determined by isotope-dilution gas chromatography-mass spectrometry, ranging from -1.3 to +1.8% (mean: +0.4%). For the reversed-phase HPLC procedure with thymine, the imprecision ranged from 0.3 to 1.3% (mean: 1.0%) and the inaccuracy from +0.1 to +3.9% (mean: +1.7%). The occasional observation of interferences with 2-iminoimidazolidin-4-one limited the application of the normal-phase method to a certain extent.
authors.affiliation: Laboratory of Medical Biochemistry and Clinical Analysis, University of Ghent, Belgium.
authors.forename: L M
authors.initials: LM
authors.lastname: Thienpont
authors.forename: K G
authors.initials: KG
authors.lastname: Van Landuyt
authors.forename: D
authors.initials: D
authors.lastname: Stöckl
authors.forename: W
authors.initials: W
authors.lastname: Saeyens
authors.forename: D
authors.initials: D
authors.lastname: De Keukeleire
authors.forename: A P
authors.initials: AP
authors.lastname: De Leenheer
mesh_terms: D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D003404:Creatinine / Q000031:analogs & derivatives* / Q000097:blood* / Q000737:chemistry; D006801:Humans; D012015:Reference Standards; D015203:Reproducibility of Results; D013056:Spectrophotometry, Ultraviolet; D013941:Thymine / Q000737:chemistry*
chemical_list: C094390:2-iminoimidazolidin-4-one; D003404:Creatinine; D013941:Thymine