Studies On The Development Of New Methods For The Determination Of Harmful Ingredients In Personal Care Products And Foodstuffs

In this dissertation, a simple, sensitive and rapid method based on chemical derivation for the determination of triclosan in personal care products is developed. In addition, new reaction systems are explored to determine nitrite in foodstuffs and diethylene glycol in toothpaste.The dissertation is divided into four sections.In the first section, spectrophotometric method and high-performance liquid chromatography spectrometry method are reviewed with the emphasis on their applications of personal care products and foodstuffs analysis.In the second section, a selective spectrophotometric method for the determination of triclosan in personal care products is described. It is based on the reaction of sodium nitrite with p-aminobenzene sulfonic acid in acidic medium to form diazo salt, with which triclosan further forms an azo compound in an alkaline medium. The resulting yellow colored product has a maximum absorption at 452 nm. A good linear relationship is obtained in the range 0.075-30 mg/L of triclosan. A detection limit of 0.075 mg/L is achieved and the relative standard deviation is 0.24% (n=11). The proposed method has been applied to the analyses of triclosan in personal care products and the results are in good agreement with those obtained by high-performance liquid chromatography.In the third section, an attempt is made to develop an analytical method for the determination of nitrite in foodstuffs, based on the same reaction system as the one used above for triclosan analysis. A good linear relationship is obtained in the range 0.055-10 mg/L of nitrite. A detection limit of 0.055 mg/L is achieved and the relative standard deviation is 0.27% (n=11). However, its sensitivity can not meet the requirement because of the low levels of nitrite in foodstuffs. In the last section, a high-performance liquid chromatographic method is developed tentatively for the determination of diethylene glycol with UV detection after pre-column derivation with benzyl chloride in the presence of catalyst. The resulting product has a maximum absorption at 230 nm. A good linear relationship is obtained in the range 37.5-5×10~4μmol/L of diethylene glycol. However, proper derivative reagents and catalysts are needed to improve its sensitivity in order that diethylene glycol in toothpaste can be detected.