| dc.description.abstract | Abstract
The purpose of this study is to develop a dispersive liquid-liquid microextraction (DLLME) technology and to develop fluorescent probes using microwave-assisted one-pot synthesis. This thesis consists of three themes, the first of which involves the rapid optimization of the DLLME technology using the experimental design method. The second theme concerns the improvement of the DLLME technology using the automatic dynamic mixing droplet technology. Finally, the third theme involves the synthesis of a new type of probe using fluorescent molecules.
In the first part, we adopted the Taguchi method and response surface methodology to optimize parametric continuity and discontinuity of the DLLME technology. The DLLME technology was integrated with the gas chromatography involving negative ion chemical ionization mass spectrometry to test six pyrethroid pesticides in agricultural products, namely Fenpropathrin, Fenvalerate, Flucythrinate, λ-Cyhalothrin, Cypermethrin, and Deltamethrin.
By using the Taguchi method and the response surface methodology, the following optimal conditions were achieved: hloroform 70 μL (extraction solvent), acetone 300 μL (dispersant), and 5% sodium chloride (salt addition concentration) were mixed in a pH 4 environment. Ultrasound was utilized in the extraction for 3 minutes, and the mixture was centrifuged for 3 minutes.
Under the optimum extraction condition, the linear range of this method was 20–50000 pg/mL, the correlation coefficient was 0.991–0.996, the detection limit was 5–35 pg/mL, and the relative standard deviation values of the inter- and intra-day analysis was 3.2%–8.5%.
This method was applied to analyze 13 real samples of the target analytes, including beverages, fruits, vegetables, and herbs. In the standard addition method, the highest concentration used was 500 pg/mL, and the relevant extraction recovery was 74%–130%.
In the second part concerned the verification of a conceptual breakthrough, which involved automatic dynamic mixing droplet DLLME (ADMD-DLLME). To effectively test the organophosphate ester concentration in the environmental water samples, the ADMD-DLLME method was developed and integrated with the gas chromatography-mass spectrometry. Droplets were stably generated with ease using syringe pumps. When the sample and the extraction solvent contacted each other and temporarily mixed, the extraction was conducted immediately. The ADMD-DLLME overcame the conventional limitation of the DLLME method that required manual handling, and no expensive equipment was involved in the automation of the DLLME method. In addition, the use of disposable sample injection syringes prevented contaminations caused by sample residue. The response surface methodology was adopted to optimize parameters affecting the ADMD-DLLME. Analysis of variance was conducted for statistical analysis. Under the optimized condition, the ADMD-DLLME method exhibited favorable linearity (1–800 µg/L), detection limit (0.1–0.4 µg/L), and reproducibility (RSD = 1.3%–10.7%). The method had been applied to samples from reservoir water, sea water, and river water.
In the last part, a rapid, inexpensive, and convenient method was developed and applied in the microwave assisted synthesis of indole-3-propionic acid–bisphenol A diglycidyl ether (IPA–SR3) fluorescent probes. The fluorescent probe exhibited the dual illumination characteristics of photo-induced electron transfer and aggregation-induced emission based on concentrations. The aggregated IPA–SR3 displayed a wavelength-dependent photoluminescence behavior; it was highly selective to Cu 2+ (Ksv = 1.5×104 M-1) and had a low limit of detection (2.9 μM). Therefore, it was applicable to detecting low-concentration Cu 2+ in water samples. | en_US |