Analysis of Acidic Herbicides in Water Using Countercurrent Chromatography

• Main Authors: Yu-lin Huang, 黃玉麟
• Other Authors: Tiing Yu
• Format: Others
• Language: zh-TW
• Published: 2001
• Online Access: http://ndltd.ncl.edu.tw/handle/91700044446131620577

碩士 === 國立交通大學 === 應用化學系 === 89 === Quantitative analysis of acidic herbicides from water can be done by solid-phase extraction first, then analyzed using high performance liquid chromatography (HPLC) or other instruments. During the extraction, considerable amount of humic substances would inevitably be extracted with the herbicides from water matrixes. The humic substances can cause a severe baseline deviation using UV/Vis detectors, thus make identification and quantification difficult. In addition, the HPLC column would be contaminated by the humic substances due to permanent adsorption to the stationary phase and shorten the column life time. Combining a “restricted access media” column with the analytical column helps reduce the baseline deviation, but significant baseline signals are usually still observed. We use a countercurrent chromatography for analysis of five acidic herbicides in place of HPLC after solid-state extraction. Since no packing material is needed for CCC columns, damage to the column due to adsorption will not happen. The lower phase of a n-hexane-ethyl acetate-water (15:7:20, v/v/v) solvent system is used as the mobile phase. Since the humic substances are more hydrophilic than the herbicides, they are eluted first and separated from the herbicides. Although five herbicides are well resolved, quantification of compound 2,4-D is somewhat affected by the tailing signal of humic substances. In addition, compound bromoxynil is excluded for quantification due to its elongated retention time. The detection limits range from 2-14 mg/L for four herbicides.