Solid-phase extraction as a clean-up procedure for the liquid chromatographic determination of benzoic and sorbic acids in fruit-derived products

A liquid-chromatographic procedure is proposed for the simultaneous determination of benzoic and sorbic acids in fruit-derived products. Prior to the chromatographic separation, a clean-up pre-treatment of the sample is carried out off-line, using successively an anionic resin and a C-18 stationary phase as sorbent beds. After elution from the cartridges, the acids are separated and quantitated by LC with UV-absorbance detection. The validation tests show that the technique can be applied to different types of fruit-derived products (i.e. jams, dried fruits and almond paste).