MINIATURIZATION OF SIZE-EXCLUSION CHROMATOGRAPHY AS A POWERFUL CLEANUP TOOL IN RESIDUE ANALYSIS

A miniaturised size-exclusion chromatography (SEC) column with a 2 mm I.D. was developed and compared to a routinely used SEC column with a 10 mm I.D. for the determination of organochlorine pesticides. The flow-rate and sample size were decreased in proportion with the decrease in diameter and the column was tested for recovery of pesticides and for clean-up of animal fat and vegetable samples. Analysis was performed with capillary gas chromatography-electron-capture detection. The miniaturised column proved to be better than the standard SEC column with regard to the removal of the matrix in vegetable samples, while comparable results were obtained with regard to recoveries obtained and results of analysis. Sample size and solvent consumption for the miniaturised SEC column as well as the volume of the collected fraction are dramatically decreased. This facilitates evaporation of solvent which may be necessary to achieve the needed limit of detection.