Study On The Determination Of Synthetic Phenolic Antioxidants

Synthetic Phenolic Antioxidants (SPAs) are widely used in food and cosmetic due to their efficient oxidation resistance and low cost. However, excessive use of SPAs may produce toxic substances that may be harmful to people’s health. Therefore, it is significant to develop a series of sensitive, reliable and convenient methods for the determination of SPAs. In this paper, analysis methods of six mostly used SPAs, such as propyl gallate (PG), tertiary butyl hydroquinone (TBHQ), butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT) octyl gallate (OG) and nordihydroguaiaretic acid (NDGA) have been studied. The main contents are as follows:Part1Study on alcohol-based vortext-assisted liquid-liquid microextraction and high-performance liquid chromatography for the Determination of Synthetic Phenolic Antioxidants in instant noodleAn alcohol-based vortext-assisted liquid-liquid microextraction (VA-LLME) method using isobutanol was developed for the extraction and preconcentration of TBHQ, BHA, OG、NDGA and BHT from instant noodle. The VA-LLME is easy to operate with high extraction efficiency and less solvent. The optimum conditions of VA-LLME were3%(v/v) isobutanol, pH5,30s vortex time and5min centrifugation time at3000r/min. The limits of detection (LOD) were3.5ng mL-1for TBHQ,2.8ng mL-1for NDGA,3.2ng mL-1for BHA,1.5ng mL-1for OG and6.4ng mL-1for BHT. Recoveries of the SPAs spiked into instant noodle were in the range92%to102%and RSD in the range of1.4%-4.3%.Part2High-performance liquid chromatography determination of antioxidants in cosmetics after cloud point extraction using dodecylpolyoxyethylene etherDodecylpolyoxyethylene ether (AEO9) is a new non-ionic surfactant to be applied in CPE. Duo to the high cloud point of AEO9itself, isooctanol was added to decrease the cloud point of AEO9and have got good result. AEO9was chosen as an extraction solvent due to its low cloud-point temperature and short phase separation time and it is well-known as an environmentally-friendly solvent. Factors affecting CPE (volume of the extraction solvent, sample pH, extraction time, and equilibration temperature) were optimized by single factor experiment. The optimum conditions of CPE were0.02%(v/v) AEO9and0.03%isooctanol; pH,7; vortex time30min, equilibrant time10min at30℃. Preconcentration factor was about32. The high recoveries of the spiked cosmetic were obtained in the range90%-105%, RSD was in the range1.8%-5.5%.Part3Study on Determination of four synthetic phenolic antioxidants in edible oils by high performance liquid chromatography with solid phase extraction using magnetic iron oxide nanoparticlesThe Fe3O4magnetic nanoparticle is compound by hydrothermal method and modified by sodium silicate to form a superparamagnetic silica-coated Fe3O4magnetie nanoparticle (Fe3O4/SiO2), and then coated by surfactants (CTAB) and applied as an effective sorbent material for the pre-concentration of SPAs from edible oil samples. In order to enhance their adsorptive tendency towards analytes, cetyltrimethylammonium bromide (CTAB) were added, which adsorbed on the surface of the Fe3O4/SiO2nanoparticles (Fe3O4/SiO2NPs) and formed mixed hemimicelles. Effect of different parameters influencing the extraction efficiency of SPAs including the concentration of Fe3O4/SiO2NPs and CTAB, pH value and absorption time were optimized. Under optimized condition the method was successfully applied to the extraction of SPAs from edible oil samples and limits of detection in the studied edible oils were in the range of2.0to8.5ng mL-1. The high recoveries of the spiked edible oils were obtained in the range84.0-90.7%. The MSPE method has been shown to be a potentially useful methodology for the preconcentration of the target analytes.