Investigation of stability of aqueous solutions containing trace amounts of volatile organic analytes

Abstract: When determining volatile organohalogen compounds in an aqueous matrix, specific properties of these compounds should be taken into consideration, when preparing aqueous standard solutions used for calibration and during model investigations, namely: [•] low boiling points; [•] high vapor pressure; and, [•] relatively low solubility in water. Because of the significance of this problem and the lack of practical information available in the literature, we carried out model investigations of stability of selected volatile analytes in aqueous solutions. The experimental results were used to estimate the time after which the result of determination may not reflect the true concentration of the analyte. The investigations provided information on: [•] the method of preparation of model solutions (in appropriate containers); [•] the method of storage and the storage time of these solutions; and, [•] number of repetitions needed in the final determination (repeated sampling of the solution from a volumetric flask, which requires the flask to be opened for each sampling). This parameter is especially important when determining the repeatability and the reproducibility in validating the procedure for TLHS-DAI-GC-ECD. [Copyright &y& Elsevier]