Soil thin-layer chromatography (TLC) is useful for rapid determination of the relative mobility (RF) of herbicides and other synthetic organic compounds (SOC) in soil but fails for volatile compounds. An alternate method using small soil chromatographic columns was developed to minimize SOC volatilization while maintaining the essential characteristics of soil TLC. The column method utilizes soil contained in narrow diameter (4 mm I.D.) glass tubes. Soil TLC and soil chromatographic columns were used to determine the relative mobility of aniline and benzoic acid in unaltered and organic-free Cecil, Holdrege, Sharpsburg, and Valentine soils. Both methods indicated that benzoic acid was more mobile than aniline in most of the soils. Variations in RFvalues between methods generally were small and suggested that either method was acceptable for laboratory estimation of the relative mobility of SOC with low vapor pressures. Differences in RFvalues may be attributed to differences in soil preparation, as TLC plates were prepared by drying thinly spread soil slurries while soil chromatographic columns contained powdered soil. Soil chromatographic columns allowed determination of RFvalues for toluene, which is too volatile for soil TLC. Toluene was less mobile than benzoic acid in all soils, and less mobile than aniline in the unaltered Valentine soil and in the organic-free soils.
ASJC Scopus subject areas
- Soil Science