Belma Imamovic, Miroslav Sober and Ervina Becic
Parabens are esters of p-hydroxybenzoic acid and belong to group of effective preservatives commonly used in cosmetic products, drugs and food. Their antimicrobial activity increases with increasing carbon number of the ester group. A number of cosmetic products and skin-care products are preserved with parabens, as well in Europe as in the United States. Methyl, ethyl and propyl paraben are preservatives commonly used in cosmetic products. Usage of parabens should be under great attention, because some studies mentioned that the increased concentration can cause skin irritation and contact dermatitis.. This paper shows optimization of HPLC method for determination of methyl, ethyl and propyl paraben in sunscreen products. The advantage of this analytic method is that the same stationary phase with different mobile phases is used for determination UV filters and parabens as well in sunscreen products. Determination was performed using reversed stationary phase C8 with wavelength 254 nm. Separation was performed using mobile phase methanol: water (60:40 w/w). Analytic method was validated through specificity, linearity, limit of detection (LOD) and limit of quantification (LOQ). Determined limit of detection and limit of quantification for methyl, ethyl and propyl paraben are respectively: LOD-0.035 μg/ml LOQ-0.116 μg/ml; LOD-0.061 μg/ml LOQ-0.203 μg/ml and LOD- 0.009 μg/ml LOQ-0.031 μg/ml. Coefficient of quantification for methyl, ethyl and propyl paraben are respectively: R2-0.9996; R2-0.9988 and R2-1. A content of parabens was examined on commercial samples available on market in Bosnia and Herzegovina. Concentration of ethyl, methyl and propyl paraben does not exceed maximal allowed concentrations (0.4% for single ester and 0.8% for mixture of esters) in tested samples.
