REVERSED-PHASE HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHIC SEPARATION OF 1-NAPHTHYL ISOCYANATE DERIVATIVES OF LINEAR ALCOHOL POLYETHOXYLATES

The optimization procedure for the reversed-phase HPLC separation of 1 -naphthyl isocyanate derivatives of linear alcohol polyethoxylates (LA Es) is reported. Using a C-18-bonded silica stationary phase and aceto nitrile-water mixtures as mobile phase, different trends in the chroma tographic separation of selected 1-tetradecanol polyethyleneglycol eth er ethoxymers were observed. In the investigated range of acetonitrile -mobile phase volume ratio (phi), the elution order of the ethoxymers was inverted by increasing the organic solvent content of the mobile p hase, and the mobile phase composition was found which provides the co -elution of the tested compounds. On the basis of the trends of capaci ty factor logarithm (log k') versus the number of ethoxy units (n) at different phi, an increased retention by increasing phi. was also pred icted for higher ethoxymers. The separation under the same chromatogra phic conditions of a C-12-C-18 LAE mixture with an average number of 1 0 ethoxy units, confirmed the strong variability of LAE chromatographi c behaviour in the investigated cp range. The isoeluting conditions fo und for the C-14 LAE ethoxymers were also applied successfully to the homologue-by-homologue separation of the C-12-C-18 LAE mixture.