Analysis of nucleosides and nucleobases by microemulsion electrokinetic capillary chromatography coupled with field-amplified sample injection

Abstract

A microemulsion electrokinetic capillary (MEEKC) chromatography method was online-coupled with field-amplified sample injection (FASI) for the analysis of nucleosides and nucleobases, namely cytidine, guanosine, N⁶-methyladenosine, fluorouracil, thymine, adenine, mercaptopurine, 6-hydroxypurine, and guanine. A microemulsion background electrolyte containing 10 mM sodium dodecyl sulfate (SDS), 0.6% (v/v) 1-butanol, 0.5% (v/v) ethyl acetate and 98.9% (v/v) borate buffer (10 mM; pH 9.0) was used as the running buffer. An online field-amplified sample injection (FASI) technique was adopted to improve the detection sensitivity. Baseline separation of nine nucleosides was achieved within 12 min with detection limits (S/N = 3) between 0.22 and 2.97 μg mL⁻¹ with the DAD detector at 200 nm under optimized conditions. The proposed method was applied to the determination of nine nucleoside compounds in spiked urine and serum samples with the recoveries ranging 91.2–113% and 85.2–112% and the relative standard deviations (RSDs, n = 3) at less than 5.90% and 8.22%, respectively.