点击次数：

论文类型：期刊论文

发表时间：2010-04-28

发表刊物：JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY

收录刊物：SCIE、PubMed、Scopus

卷号：58

期号：8

页面范围：5004-5010

ISSN号：0021-8561

关键字：Metalaxyl; metalaxyl acid; analytical method; trace water; enantiomeric separation

摘要：The separation of chiral transformation products greatly complements the understanding of the stereochemistry of chiral pollutants. In this study, direct enantiomeric resolution of metalaxyl and its main degradation product metalaxyl acid, often co-occurring in the environment, was carried out in normal-phase high-performance liquid chromatography with a Chiralcel OJ-H column. (R)-Metalaxyl acid and (S)-metalaxyl, which were almost parallel bonding to the chiral stationary phase, tended to separate, started to overlap, coeluted, and separated again with subtle changes of the mobile phase consisting of n-hexane, 2-propanol, acetic acid, and trace water. Their competition above hampered an acceptable direct separation in fresh mobile phases. Aged mobile phases with a storage period of 3-5 days, however, significantly improved their separation, in which trace water from moisture air diffusion was found to play a major role. Trace water differentially affected peak width and retention times and then induced enhanced peak separation, confirmed by deliberate addition of water to fresh mobile phases. Furthermore, none of the studied factors, involving temperature, concomitant analytes, and trace water, could cause changes of the configuration of the chiral stationary phase. Simultaneous enantiomeric separation of both compounds was achieved in aged or fresh mobile phases with adventitious or added water and gave satisfactory peak separation, all with Rs values of more than 1.20 in environmental samples.