Determination of nucleotides in fish tissues using capillary electrophoresis

Capillary electrophoresis has been applied to quantitate nucleotide degradation in fish tissues, to provide a basis for determining the K value, an indicator of fish freshness. The three major compounds, inosine monophosphate (IMP), inosine (HxR), and hypoxanthine (Hx) were distinctively separated at 416 V/cm applied potential, 100 mM CAPS buffer, pH 11. There was a good correlation between the peak area and the nucleotide concentration. By using a short distance (22 cm) from the sample entrance to the detector, the identification and determination of these compounds in each sample were completed within 15 min. The results obtained correlated very well with those obtained by enzymatic assays. The capillary was completely regenerated with 1 N NaOH, to dissociate all bound materials from the capillary wall, mainly cations in the fish extract. This provided the same silica surface for repeated runs, resulting in reproducible electropherograms.