Development of a solid-phase extraction/gas chromatographic–mass spectrometric method for quantification of succinic acid in nucleoside derivatives for oligonucleotide synthesis

A solid-phase extraction (SPE)/gas chromatographic–mass spectrometric (GC–MS) method was developed for analysing residual succinic acid in nucleoside derivatives to be used in oligonucleotide synthesis. Use of a SPE protocol, enabled most of the derivatives to be trapped, thereby creating eluates enriched in succinic acid. GC–MS was used to quantify the amount of residual succinic acid in four different nucleoside preparations, with succinate concentrations varying from 0.18 to 0.24% (w/w). The within-day repeatability of the method was found to be 1.25% RSD. A linear relationship was observed between the amount of succinic acid in the sample and the GC–MS peak area, with a correlation coefficient of 0.9997 in the concentration interval 0.05–2.5% (w/w). Recoveries were measured by the addition of internal standards to working solutions and varied between 99.8 and 102.6%.