title: Determination of free serum didanosine by ultrafiltration and high-performance liquid chromatography.
abstract: An isocratic reversed-phase high-performance liquid chromatographic method was developed to determine free didanosine concentrations in human serum. An ultrafiltration technique was used to recover didanosine from the samples. didanosine was analyzed using a 150 mm x 3.9 mm I.D. Nova-Pak phenyl column and a mobile phase of 0.02 M sodium citrate (pH 5)-isopropanol (97.5:2.5, v/v) with detection set at 250 nm. Linearity was verified from 25 to 3000 ng/ml. The limit of detection at a signal-to-noise ratio of 3 was 25 ng/ml. The mean recovery of didanosine added to serum at 50, 100, 250 and 750 ng/ml was 97.4%, 97.3%, 92.9% and 95.4%, respectively. A within-day variation of 3.6% at 50 ng/ml and 1.7% at 250 ng/ml, and a day-to-day variation of 9.3% at 50 ng/ml and 3.6% at 230 ng/ml were found. Stability studies indicated that didanosine is stable in serum for at least 8.5 months at 20 degrees C, 4 degrees C and -20 degrees C.
authors.affiliation: Servei de Bioquímica, Hospital General Universitari Vall d'Hebron, Barcelona, Spain.
authors.forename: M L
authors.initials: ML
authors.lastname: Rosell-Rovira
authors.forename: L
authors.initials: L
authors.lastname: Pou-Clavé
authors.forename: R
authors.initials: R
authors.lastname: Lopez-Galera
authors.forename: C
authors.initials: C
authors.lastname: Pascual-Mostaza
mesh_terms: D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D016049:Didanosine / Q000097:blood*; D006801:Humans; D018894:Reverse Transcriptase Inhibitors / Q000097:blood*; D013056:Spectrophotometry, Ultraviolet; D014462:Ultrafiltration / Q000379:methods*
chemical_list: D018894:Reverse Transcriptase Inhibitors; D016049:Didanosine