Application Of Supramolecular Solvents-based Extraction For The Determination Of Total Phthalate Esters

The extensive utilization of plastic products has lead to ubiquitous contamination of phthalate esters(PAEs) in food and environmental samples. However, there are following questions exist in analytical process of PAEs. It is labor-intensive and time-consuming to extract and detect all PAEs owing to their diverse polarity. Purication process is necessary to reduce matrix interferences in complex samples. Furthermore, process contamination can lead to deviation in PAEs quantification. To solve above questions, some methods for the determination of total PAEs are proposed. These methods can quickly screen samples by simplifing the pretreatment of PAEs and evaluate PAEs pollution level more comprehensively and accurately. During the process, all of the PAEs are translated to phthalic acid(PA) by hydrolysis, and PA is difficult to extract for its high polarity, so supramolecular solvents(SUPRASs) are chosen to extract PA by hydrogen bond interaction. SUPRASs can not only result in high extraction efficiencies for PA but also purify extractant by their restricted access property.This work mainly studies the application of SUPRASs-based extraction for the determination of total PAEs in edible oils and soils which respectively represent complex food and environmental samples. The specific research content is divided into the following two parts:1. A new method for the rapid determination of total phthalates(PAEs) in edible oils by phase transfer catalyst(PTC) assisted hydrolysis and SUPRASs-based extraction was developed. The PAEs in edible oils all were translated to phthalic acid by tetrabutylammonium bromide(TBAB) assisted hydrolysis. Then phthalic acid was extracted by the SUPRAS made up of octanol and tetrahydrofuran and aqueous solution or by tributyl phosphate(TBP) through dispersive liquid-liquid microextraction(DLLME). Meanwhile,these two methods were compared. Finally, PA was detected by high performance liquid chromatography-tandem mass spectrometry(HPLC-MS/MS). Under the optimal conditions,hydrolysis time was 10 min. The linear range of phthalic acid was 50~2000 μg L-1 with a good correlation coefficients(r>0.999). The limits of detection(LOD) and quantification(LOQ)were 5.41 and 18.1 μg kg-1, respectively. The recoveries of target analyte in the three levels ofspiked samples were in the range of 84.6%~105%. The repeatabilities, expressed as relative standard deviations(RSDs), were 2.6% for intra-day and 3.7% for inter-day. The total PAEs contents of 12 edible oils were found in the range of 0.300~1.09 mg kg-1.2. A simple, rapid and economic method was developed for the quantification of total PAEs in farmland soils using PTC assisted hydrolysis and SUPRASs-based extraction combined with HPLC-MS/MS. In hydrolysis process, a one-step hydrolysis method was provided and it was compared with ultrasonic extraction or soxhlet extraction coupled with hydrolysis. The results shown the one-step hydrolysis had obvious advantages in hydrolysis rate, hydrolysis time and solvent consumption. TBAB was selected as the most effective PTC in one-step hydrolysis, and the hydrolysis time was optimized to 20 min. The resulting phthalic acid in acidified hydrolysate was extracted with octanol-based SUPRAS without purification process. The method was validated in terms of linearity, precision, recovery and matrix effect. As a result, no obvious matrix effect existed between SUPRAS and soil extracts.The detected limit was 2.49 nmol g-1, and the quantification limit was 3.64 nmol g-1. The recovery rates ranged from 91.2% to 107% with RSDs ranged from 0.5% to 7.3% in all of the tested conditions. Fifteen samples collected from four provinces of China were analyzed, and the background corrected total PAEs contents were 1.44~119 nmol g-1.