Capillary gas chromatography with four different detectors for dinitroaniline herbicides in human body fluids

A simple and rapid method for extraction of seven dinitroaniline herbicides from human whole blood and urine using Sep-Pak C18 cartridges is presented. After mixing with distilled water, whole blood and urine samples containing the herbicides were loaded on Sep-Pak C18 cartridges and eluted with chloroform-methanol (9:1). The recovery of the seven compounds that were added to whole blood and urine was more than 91%. The herbicides were detected by capillary gas chromatography (GC) with electron-capture detection (ECD), surface-ionization detection (SID), nitrogen-phosphorus detection (NPD), and flame-ionization detection (FID). GC-ECD generally gave the highest sensitivity for all herbicides, whereas GC-FID gave the lowest sensitivity. Isopropalin could be detected by GC-SID with a sensitivity comparable with that of GC-ECD; high sensitivity could also be obtained for isopropalin, pendimethalin, and nitralin using GC-NPD. The calibration curve for the seven herbicides measured by GC-ECD showed linearity in the range of 0.047-3.0 pmol on-column. The detection limits of the herbicides were 24-45 fmol on-column for whole blood and 19-40 fmol on-column for urine.