The main parameters influencing extraction and determination were investigated in

Apparatus
UV-vis Spectrophotometer Model TU-1901 (Beijing Puxi General Instrument Co., Ltd, Beijing, China) was used for the determination.
An ultrasonic cleaner with temperature control Model SB5200DT (Ultrasonic power: 200 W, Ultrasonic frequency: 40 kHz, Ningbo Xinzhi Biotechnology Co., Ltd, Ningbo, China) was used for ultrasonic extraction for UA-CPE and UA-DLLME.
A centrifuge Model TDL-5-A (Shanghai Anting Scientific Instrument Factory, Shanghai, China) was used for phase separation experiments in 40 mL conical tubes.