Trace Quantification of Methyl Paraben in Cosmetic Samples Based on Fe-MIL-NH2 Functionalized With Isatin Schiff Base

Abstract

Preservatives are substances used to enhance the quality or nutritional value of health, pharmaceutical and food flavors, and to prevent them from being broken down by microorganisms [1]. Methyl paraben and propyl paraben are effective antibacterial and antifungal agents that are commonly used as preservatives in food, beverages, cosmetics and pharmaceuticals [2]. Parabens are considered as an ideal preservative due to their antimicrobial activity, high resistance to pH changes, relatively safe use and low production cost. Due to the benefits of preservatives, they can cause problems such as disorders of the immune system and endocrine glands. Therefore determination of parabens is important [3]. In this study, Fe-MIL-101-NH2 functionalized with isatin Schiff base was synthesized and characterized by Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD) analysis. Dispersive micro-solid phase extraction (Dμ-SPE) was used as a green, simple and efficient method for trace quantification of methyl paraben (MP). Four independent parameters of pH, adsorbent amount, temperature, and ultrasonic time were selected as factors influencing the process and optimized by central composite design (CCD) [4]. In Dμ-SPE method, a solution containing the appropriate amount of MP was placed in a 30 mL centrifuge tube. The pH of the sample solution was adjusted to 6, then the adsorbent was dispersed in the sample solution by ultrasonic device and the adsorbed analytes were eluted with a 0.7 mL of acetonitrile and transferred to the spectrofluorimetry cell. Under optimal conditions, linear range of 35-650 ng mL-1, detection limit of 9.19 ng mL-1 and relative standard deviation (R.S.D) of 3.5% were obtained for the target analyte. Finally, the proposed method was successfully used for preconcentration and determination of methyl paraben in cosmetic samples.