High performance liquid chromatography (HPLC) may be used for analysis of municipal wasterwater containing ethoxylated alcohol surfactants. After cleanup of the sample by XAD‐2 resin, liquid‐liquid extraction, ion exchange and cobalt thiocyanate extraction, the surfactant is derivatized with phenyl isocyanate to permit UV detection and analyzed by both normal phase and reversedphase HPLC. The alkyl chain length distribution is determined using reversed‐phase HPLC, while the ethoxy chain length is determined by normal phase HPLC. The limit of quantification is 0.1 ppm.

A high performance liquid chromatography (HPLC) method using adsorption columns combined with linear gradient elution has been developed for the determination of ethylene oxide (EO) distribution in nonionic surfactants. The quantitative ethoxylate adduct distribution in single-carbon-number and mixed-carbon-number primary alcohol-based samples can be obtained. The HPLC method is also applicable for determining the molar EO distributions in diverse ethylene oxide adduct compounds such as alkylphenol ethoxylates, branched alcohol ethoxylates and secondary alcohol ethoxylates. Nonionic surfactant samples containing adducts up to 25 mol have been successfully separated and the individual adducts quantitated.

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A high performance liquid chromatography (HPLC) method for the determination of intact and partially degraded linear alkyl‐benzene sulfonate (LAS) was developed. The LAS degradation products resulting from a semicontinuous activated sludge (SCAS), a die‐away CO2 and a simulated river die‐away study were quanti‐tatively determined by HPLC equipped with a reversed‐phase column using a tetrahydrofuran/water/Pic A solution as the mobile phase. The column effluent was monitored with a fluorescence spectrophotometer that was operated at an excitation wavelength of 232 nm and an emission wavelength of 290. Compounds investi‐gated included both single‐and mixed‐carbon‐range materials. The HPLC method shows good correlations with MBAS for intact LAS material. The most significant advantage of this method over MBAS is it ability to quantitatively determine partially degraded intermediates and the disappearance of those intermediates. This method, when using the fluorescence detection system, is selective for sulfonated ring structures with more than one alkyl carbon. The sensitivity of the method is in the 0.05‐ppm range. It can be used not only for samples from laboratory experiments but also for sewage plant influents, effluents and river waters.

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