Design and applications of a new fluorimetric assay of thioguanine in liposomes.
This paper describes the systematic design of a modification that overcomes the difficulties encountered with the original fluorimetric method for thioguanine. It allows the determination of thioguanine alone, as well as in a lipid medium (specifically in liposomes). It consists of an earlier lipid extraction based on liquid-solid extraction cartridges; then the oxidation of thioguanine in the lipid-free solution is performed by adding hydrogen peroxide in pH 4.7 acetate buffer at 50 degrees C for 30 min. A central composite design was used to finally optimize the method. The assay is precise (RSD values were 1.8 and 2.1% for intra-day and between-day precision, respectively). The detection limit was 0.05 microM and the limit of quantitation 0.08 microM.
Foradada
M
M
Unitat de Fisicoquímica, Facultat de Farmàcia, Universitat de Barcelona, Spain.
Gallardo
M
M
Estelrich
J
J
D006861:Hydrogen Peroxide; D008081:Liposomes; D012107:Research Design; D012680:Sensitivity and Specificity; D013050:Spectrometry, Fluorescence / Q000379:methods*; D013866:Thioguanine / Q000032:analysis*
D008081:Liposomes; D006861:Hydrogen Peroxide; D013866:Thioguanine