Development of Micro-Solid Phase Extraction Sorbent for Trace Organic Compounds Analysis

Abstract

This thesis aimed to develop the micro-solid phase extraction for trace organic compounds analysis. Two sub-projects were carried out. The first sub-project is the development of chitosan-polyaniline microbeads for the extraction of four parabens including methylparaben, ethylparaben, propylparaben and butylparaben before analysis by high performance liquid chromatography-ultraviolet detection (HPLC-UV). Some affecting parameters were optimized such as the number of microbeads, adsorption and desorption times and type of desorption solvent. The sorbent was used to extract four parabens at the concentration of 0.50 mg L1, the extraction recoveries in the range of 68.0±7.7-98.8±3.8% were obtained. These results indicated that the developed chitosan-polyaniline microbeads have a potential to be applied for the extraction of parabens in real samples. In the second sub-project, the polypyrrole magnetic microsphericals were synthesized and used as a sorbent to extract carbamate pesticides (carbaryl, carbofuran and methomyl) before the extractant was analyzed by high performance liquid chromatography-diode array detector (HPLC- DAD). Under the optimum conditions, the developed method provided wide linear ranges (0.50 to 1.2×103 μg L-1, 1.0 to 7.5×102 μg L1 and 2.5 to 5.0×102 μg L-1) with low limits of detection (0.228±0.017 μg L1, 0.78±0.20 μg L1 and 2.10±0.12 μg L-1) for carbaryl, carbofuran and methomyl, respectively. Good accuracy (recoveries in the range of 81.6±1.5% to 108.5±1.1%) and good precision (RSDs in the range of 0.11- 4.5%) were also presented. In addition, this developed sorbent provided good reproducibility (RSDs in the range of 0.38-4.4% for 6 batches) and good reusability (24 extraction cycles). Using the developed method to measure three carbamate pesticides in fruit and vegetable samples, carbaryl was detected in apple at the concentration of 0.458±0.038 μg L-1, carbofuran was found in tomato at the concentration of 1.89±0.10 μg L-1 and methomyl was found in watermelon at the concentration of 5.79±0.28 μg L-1