Add time:07/14/2019         Source:sciencedirect.com

In connection with the acquisition of knowledge for an expert system for solid-phase extraction (SPE), a preliminary investigation was made of the kinds of sorbents that can be used for the SPE of small acid analytes. The development of a simultaneous solid-phase extraction of the preservatives benzoic acid and sorbic acid and the artificial sweeteners saccharin and aspartame is presented. Both preservatives and saccharin are retained on a silica-based quaternary ammonium anion exchanger. Elution is effected with a mixture of methanol and 1% sulphuric acid. Aspartame is not retained on the anion exchanger, but the collected adsorption and was solvents containing the aspartame can be extracted on the octadecyl sorbent. The extracts are chromatographed in the reversed-phase mode on a C18 column with a mobile phase consisting of phosphate buffer (pH 4.5, ionic strentht 0.1) and acetonitrile. Recoveries of at least 95% were observed and the relative standard deviation was < 3.2%. Comparison of an external callibration line for aqueous standard solutions, a calibration line for extracted aqueous samples and a standard addition line for soft drinks showed that the developed method is unbiased when applied to concentrations of up to 20 mg l−1 in soft drinks.

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