Estimation of polyoxyethylene chain distribution of alcohol and alkylphenol ethoxylates

Oxyethylated nonylphenol and alcohols were analyzed by HPLC on normal phases with mixtures of hexane, 2-propanol and water as mobile phases, using UV and evaporative light scattering (ELS) detectors. Effects of selected analytical conditions (type of detector, drift tube temperature and gradient) on determined distributions are discussed. The distributions of oxyethylated alcohols obtained in the presence of NaOH and calciumbased W7TM catalyst and polyoxyethylene glycols present in products were compared. The distribution of oxyethylated alcohols and alkylphenols were fitted for normal distribution characterized by the mean and the standard deviation. It was found that the analytical results fitted the normal distribution quite well. The estimated mean agrees with the average degree of oxyethylation and the standard deviation can be used as a measure of the distribution broadness.