DETERMINATION OF THE CHLOROFLUOROCARBON SUBSTITUTE 1,1,1,2-TETRAFLUOROETHANE (HFA-134A) IN HUMAN AND ANIMAL BLOOD USING GAS-CHROMATOGRAPHY WITH HEADSPACE ANALYSIS

A gas chromatographic procedure with headspace analysis and flame-ioni zation detection is described for the determination of the chlorofluor ocarbon substitute 1,1,1,2-tetrafluoroethane (HFA-134a). A 0.5-2 ml sa mple of heparinized whole blood from a laboratory animal or human is a dded directly into a presealed headspace vial from which an equivalent volume of air has been removed. The internal standard 1,1,2,2-tetrafl uoroethane is added and the sample frozen until analysis. Chromatograp hic separation is achieved using a PoraPlot Q porous-layer capillary c olumn. The analytical range is 5.8-3298 ng/ml when 2-ml human blood sa mples are used. The concentration range of the calibration curve can b e easily adapted to accommodate the concentrations expected in either pharmacokinetic or toxicokinetic studies. Automation of the assay perm its the maximum number of samples to be processed in a day.