INFLUENCE OF DISSOLVED-GASES IN THE DYNAMIC HEADSPACE ANALYSIS OF STYRENE AND OTHER VOLATILE ORGANIC-COMPOUNDS AND IMPROVEMENT OF THEIR DETERMINATION

The on-line purge and trap dynamic headspace technique (PTI) was optim ized for styrene. High-boiling volatiles such as styrene were efficien tly desorbed from oil and from oil-water matrices. The effects governi ng the desorption were identified by comparison with an off-line proce dure. The recovery of styrene depends dramatically on the amount of fa t and on the desorption temperature. For oil-water systems, the aqueou s phase had to be saturated with both sodium chloride and carbon dioxi de; with PTI, no desorption occurs if the sample is initially degassed ; regassing improved desorption, carbon dioxide giving the best result s.