Residue Analysis of Quinclorac in Soil by Supercritical Fluid Extraction and Fluorogenic Derivatization Coupled with High Performance Liquid Chromatography

초임계추출과 형광유도체를 이용한 HPLC 에서의 Quinclorac 의 토양중 잔류분석

A new analytical method was developed by HPLC after supercritical fluid extraction and fluorogenic derivatization for the determination of quinclorac (3,7-dichloro-8-quinoline carboxylic acid) in soil. The graminicide quinclorac was extracted from soil by supercritical fluid extraction. Supercritical carbon dioxide at 7000 psi $(80^{\circ}C)$ modified with 30% of methanol extracted quinclorac from soil samples at the level of $0.1ng\;g^{-1}$ with 96% recovery. Extracted quinclorac was determined by HPLC as a fluorescent derivative. Derivatization was made with 4-bromomethyl-7-methoxycoumarin (4-Br-Mmc) using 18-crown-6-ether as a catalyst. The conversion was completed within 30 min and the limit of detection was 0.5 ppb to prove that the procedure could be used in the residue analysis of the pesticides containing carboxylic acid group.

감도와 재현성이 높은 quinclorac 의 토양중 잔류분석방법 개발을 위해 $CO_2$를 이용한 초임계추출후 4-bromomethyl-7-methoxycoumarin 로 형광유도체화하여 HPLC 상에서 분석하는 방법을 개발하였다. 추출변수로 추출압력과 modifier인 methanol 의 함량을 변화시켜, 100 ppb 처리토양에서 7000 psi $(80^{\circ}C)$, 30% $(methanol/CO_2\;v/v)$) 조건을 이용하여 96% 의 회수율을 얻었다. 18-crown-6-ether 를 촉매로 한 형광유도체 반응은 상온에서 30분이내에 정량적으로 완결되었으며 HPLC-형광분석검출기를 이용하여 토양중 quinclorac의 최소검출 수준을 0.5 ppb까지 낮출 수 있었다. 이 방법은 기존의 방법에 비해 간편하고 감도가 높아 carboxylic acid를 함유한 농약의 잔류분석에 이용될 수 있다고 판단된다.