HEADSPACE SOLID-PHASE MICROEXTRACTION AND GAS-CHROMATOGRAPHIC DETERMINATION OF DINITROANILINE HERBICIDES IN HUMAN BLOOD, URINE AND ENVIRONMENTAL WATER

Solid-phase microextraction (SPME) is a unique extraction and sampling technique, and it has been used for separation of volatile organics f rom water or other simple matrices. In this study, we have used SPME t o separate dinitroaniline herbicides from complicated matrices of huma n urine and blood in order to broaden its application to biomedical an alysis. The SPME conditions were optimized for water, urine and blood samples, in terms of pH, salt additives, extraction temperature, and f iber exposure time. Urine or water (1.0 ml) spiked with herbicides and 0.28 g of anhydrous sodium sulfate was preheated at 70 degrees C for 10 min, and a polydimethylsiloxane-coated fiber for SPME was exposed t o the headspace at 70 degrees C for another 30 min; while spiked blood (0.5 ml) diluted with water (0.5 ml) was treated at 90 degrees C in t he same way. The herbicides were extractable under these conditions, a nd could be determined by gas chromatography-electron capture detector (GC-ECD). The recoveries of the herbicides, measured at the concentra tions of 0.50 and 1.0 ng/ml urine or water, or 6.0 and 20 ng/0.5 mi bl ood, ranged from 35 to 64% for different herbicides from water or urin e, and from 3.2 to 7.2% from blood. The headspace SPME yielded clean e xtracts of dinitroaniline herbicides from urine, blood or water, which could be directly analyzed by GC-ECD without further purification. Th e peak areas of the extracted herbicides were proportional to their co ncentrations in the range 0.1-10 ng/ml in water or urine, or 1-60 ng/0 .5 ml in blood. The lowest detectable concentration of the herbicides lay in 0.1 ng/ml water or urine, or in 0.5 ng/0.5 ml blood. The intra- and inter-day coefficients of variation were within 14% for most of t he analytes. Although the recoveries of the herbicides were rather low , the linearity of calibration curve and the precision were good. The developed method is more sensitive and much simpler in sample preparat ion than previously reported ones. With the established SPME method, a dosed herbicide was successfully separated and determined in rats' bl ood. (C) 1998 Elsevier Science B.V. All rights reserved.