Simultaneous Filtration and Liquid Chromatographic Microextraction with Subsequent GC-MS Analysis To Study Adsorption Equilibria of Pesticides in Soil

• Published in: Environmental science & technology Vol. 33; no. 18; pp. 3254 - 3259
• Main Authors: Ramos, L, Vreuls, J. J, Brinkman, U. A. Th, Sojo, L. E
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 15.09.1999
• Subjects: Analysis methods; Applied sciences; Chromatography; contaminants; Contamination; Earth sciences; Earth, ocean, space; Engineering and environment geology. Geothermics; Exact sciences and technology; gas chromatography; mass spectrometry; organic soils; Pesticides; Pollution; Pollution, environment geology; Soil and sediments pollution; Soils; Chemical analysis; Filtration; Methodology; Coupled method; Pesticides; Liquid chromatography; Partition coefficient; Soil pollution; Sorption; Gas chromatography; On line processing; Soil interaction; Phase partition; Measurement method; Mass spectrometry
• ISSN: 0013-936X; 1520-5851
• DOI: 10.1021/es990094g

Understanding the sorption equilibria of microcontaminants in soils requires the determination of the adsorbed analytes as well as those remaining in solution. On-line filtration-plus-LC-type microextraction offers an efficient alternative to the time-consuming classical procedures. The feasibility of a new simultaneous filtration-plus-liquid-chromatographic microextraction system with subsequent GC-MS to study the partition equilibrium of pesticides in the interface soil−water was investigated. The method allows the determination of the amount of pesticide adsorbed in the soil and that remaining in solution by a single injection of the total slurry. As an example, the adsorption equilibria of selected pesticides, ranging from relatively polar triazines to nonpolar compounds such as hexachlorobenzene or bromophos-ethyl, in an organic soil were studied. Once separated and preconcentrated, the filter and the solid-phase cartridge fractions were independently dried by a stream of nitrogen, extracted with methyl acetate, and analyzed by GC-MS. The standard deviations for the total procedure were lower than 6.2% (soil) and 10% (solution). The soil−water partition coefficients calculated for the selected compounds showed a good correlation with published octanol−water partition coefficients (r  2 = 0.973). This demonstrates clearly the practicality of the proposed methodology for adsorption equilibrium studies.