Stability study of selected adenosine nucleosides using LC and LC/MS analyses

The stability of the naturally occurring nucleoside, adenosine, and two synthetic chlorine-containing analogues, 2-chloroadenosine and 5'-chloro-5'-deoxyadenosine was studied using high performance liquid chromatography (LC) and liquid chromatography in combination with mass spectrometry (LC/MS). The stability of the examined nucleosides over pH range of 2-10 and at temperatures 40, 60 and 80 degrees C was measured using an LC method, whereas the products of hydrolysis were identified using LC/MS. The LC data indicated that the hydrolysis of the nucleosides followed pseudo-first order kinetics. The MS data proved that the fragment ions at m/z 136.3 and 170.3 referred to the hydrolytic products, adenine and 2-chloroadenine, respectively. The calculated values of the hydrolysis rate constant and half-life indicated that the presence of chlorine atom in the nucleoside base moiety increases apparently the stability of 2-chloroadenosine against acid hydrolysis compared to 5'-chloro-5'-deoxyadenosine and adenosine.