Determination of trace c(1)-c(4) aliphatic alcohols in aqueous samples by 9-fluorenylmethyl chloroformate derivatization and reversed-phase high-performance liquid chromatography

A simple procedure for precolumn fluorescence derivatization of low-molecular-weight aliphatic alcohols (C(1)-C(4)) with 9-fluorenylmethyl chloroformate is presented. The derivatization reaction proceeds in 1:1 (v/v) aqueous-acetonitrile solution at room temperature with a sodium phosphate buffer of pH 12.5 as a catalyst. Stable fluorescent derivatives of the alcohols are formed within 10 min. The four derivatives are separated by reversed-phase high-performance liquid chromatography and detected by a fluorescence detector at an excitation wavelength of 259 nm and an emission wavelength of 311 nm. The method detection limits are 4, 40, 70, and 30 pmol for methanol, ethanol, propanol, and butanol, respectively, per 5-μL injection volume. The relative standard deviations are 3.7% for methanol at 75 pmol and 2.1, 1.5, and 2.2% for ethanol, propanol, and butanol, respectively, at 750 pmol. As a preliminary application, the method was used to determine methanol concentration in laboratory air and ethanol content in a commercial alcoholic beverage.