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The alkyl esters of p-hydroxybenzoic acid at the C-4 position, “the parabens,” including methyl, ethyl, propyl, and
butyl, are widely used as antimicrobial preservatives in foods, cosmetics, and pharmaceuticals. Official regulations on the use
of these compounds make their analysis essential for the estimation of their exposure. On this basis, the presented study was
realized to develop a simple, selective and cheap high-performance liquid chromatographic method for the quantitative
determination of methyl paraben (MP), ethyl paraben (EP), n-propyl paraben (NPP), isopropyl paraben (IPP), n-butyl paraben
(NBP), isobutyl paraben (IBP) and benzyl paraben (BP) in pharmaceuticals and cosmetic products. The chromatographic
separation of the analytes was achieved under flow rate gradient elution conditions using a C18-bonded core-shell silica particle
column (2.6 μm particle size, 150 × 3.0 mm from Phenomenex Co.). The samples were injected into the system as aliquots of
1.0 μL, and the compounds were detected by using a photodiode array detector set at 254 nm wavelength. With this technique,
seven paraben derivatives can be determined in the concentration range of 250-2000 ng/mL. The recovery of the method is in
the range of 99.95-13.84%, and the RSD is at a maximum value of 3.95%. The proposed method was fully validated and
successfully applied to different pharmaceutical and cosmetic samples (n=16), including syrups, suspensions, oral sprays, gels,
etc. At least one paraben derivative was detected in six of the samples, and was determined quantitatively. The maximum
amount of a paraben derivative found in the analyzed samples is 321.7 ng/mL, which was MP. To the best of our knowledge,
this is the first LC method, which is applicable both on pharmaceutical and cosmetic samples.
Photodecomposition of o-phthaldialdehyde-derivatized amino acids by the photodiode array detector during their high-performance liquid chromatographic analysis
