title: Gentamicin assay in human serum by solid-phase extraction and capillary electrophoresis.
abstract: We describe the development of a capillary electrophoresis method for the determination of gentamicin C1, C1a, C2a, and C2 components in human serum. Using a weak cation-exchanger with 20 mM phosphate buffer, pH 7.4, 200 mM borate buffer, pH 9.0, and ammonia/methanol, solid-phase extraction (SPE) of gentamicin components from the human sera was performed. The extract was derivatized with 1,2-phthalic dicarboxaldehyde/mercaptoacetic acid reagent. The derivatives were separated with a background electrolyte comprising 60 mM 2-(N-cyclohexylamino)ethanesulfonic acid (CHES) buffer at pH 9.5 containing 31.6% m/v methanol, and quantified with UV-light absorption detection at 230 nm. The identity of the gentamicin components was confirmed by mass spectrometry. The SPE recovery of the gentamicin ranged from 78% to 93%. The calibration curves were linear from the concentration limit of quantitation (LOQ) to 30 mg/L for the gentamicin mixture. The LOQ for gentamicin C1 was 0.33 mg/L, for C2a 0.23 mg/L, C2 0.25 mg/L, C1a 0.27 mg/L and the concentration limit of detection (LOD) for C1 was 0.15 mg/L, C2a 0.11 mg/L, C2 0.12 mg/L, C1a 0.13 mg/L. Intra-assay relative standard deviation (RSD) values were for C1 (5%), C1a (7%), C2 (6.5%) and C2a (9%); inter-assay RSD values were for C1 (11%), C1a (13.3%), C2 (15%) and C2a (14%). The Pearson's correlation between capillary electrophoresis and immunoassay revealed a linear relationship between these two techniques with r = 0.9. This method for determination of gentamicin C1, C1a, C2a, and C2 in human serum can thus be used in the entire therapeutic concentrations range of gentamicin.
authors.affiliation: Laboratory for Pharmaceutical Chemistry and Drug Analysis, K.U. Leuven, Leuven, Belgium.
authors.forename: Eliangiringa
authors.initials: E
authors.lastname: Kaale
authors.forename: Yinhua
authors.initials: Y
authors.lastname: Long
authors.forename: Humphrey Azambeh
authors.initials: HA
authors.lastname: Fonge
authors.forename: Cindy
authors.initials: C
authors.lastname: Govaerts
authors.forename: Koenraad
authors.initials: K
authors.lastname: Desmet
authors.forename: Ann
authors.initials: A
authors.lastname: Van Schepdael
authors.forename: Jos
authors.initials: J
authors.lastname: Hoogmartens
mesh_terms: D019075:Electrophoresis, Capillary / Q000379:methods*; D005839:Gentamicins / Q000097:blood* / Q000302:isolation & purification / Q000627:therapeutic use; D006801:Humans; D013058:Mass Spectrometry; D015203:Reproducibility of Results; D009764:o-Phthalaldehyde / Q000737:chemistry
chemical_list: D005839:Gentamicins; C100093:gentamicin C; D009764:o-Phthalaldehyde