Among the different preservatives allowed for use in foods, benzoates, sorbates and parabens can be highlighted. These preservatives act as antimicrobial agents, protecting food against contamination by molds, yeasts and bacteria (ESIMBEKOVA et al., 2017). Once these substances are strange to our body, being potentially toxic, it is necessary to control the exposition, as well as establishing safe limits for their usage. The evaluation of safety in use of preservatives is based on the control of the Acceptable Daily Intake (ADI), which means the amount of substances that can be ingested daily without risks to health, even in long exposure. For such purpose, the continuous evaluation of these levels in different foods is necessary. In this work, a method for the determination of preservatives in processed foods from different categories, such as dairy products, non-alcoholic beverages, spices and sauces, fruit jams and pastes, preserves and artificial sweeteners was optimized. The method deal with extraction by Salting-out Induced Liquid-Liquid Microextraction (SILLME) with determination by High Performance Liquid Chromatography with Ultraviolet Detector (HPLC-UV). After the evaluation of MgSO₄ amount, sample pH and the addition of NaCl, the method was performed as follows: 1 g sample was weighed in a 15 mL polypropylene tube and acetate buffer pH 4.2 was added up to 5 mL. Then, 1 mL acetonitrile was added to the mixture, which was vortexed for 1 min.After, 2 g MgSO₄ were added to the mixture, which was agitated again, followed by centrifugation for 5 min at 7793 x g; finally, 500 μL of the acetonitrile layer was collected and diluted up to 1 mL with ultrapure water in a HPLC vial. Experiments were performed in triplicate. The method proved to be accurate, with recoveries between 80 and 103%, and precise, with relative standard deviation ≤ 11% and measurement uncertainty ≤ 31%. The method limits of quantification were between 0.03 and 0.07 mg kg^-1, being adequate for the determination of these preservatives in processed food samples. SILLME method was applied successfully in the determination of preservatives in processed foods, being determined concentrations up to 814 mg kg^-1 for benzoate, 1154 mg kg^-1 for sorbate and 461 mg kg^-1 for methylparaben. Additionally, this method was compared to a previously optimized QuEChERS method developed by our group (ARIAS et al., 2019), where data agreement between 94 to 99% was achieved. Finally, an efficient and simple method was developed that can be used in replacement of the traditional ones in routinely determination of preservatives in different kind of foods, with the advantages of being simpler, faster and cheaper than the official methods.

ARIAS, J. L. O.  et al. Fast and simple method of simultaneous preservative determination in different processed foods by QuEChERS and HPLC-UV: Method development, survey and estimate of daily intake. Food Chemistry, v. 293, p. 112-119, 2019.

ESIMBEKOVA, E. N.  et al. Inhibition effect of food preservatives on endoproteinases. Food Chemistry, v. 235, p. 294-297, 2017.