ABSTRACT
Solven t ex t rac t ion is an attractive m e t h o d for concen t ra t ing a pa r t i cu la r f ract ion of the d i s s o l v e d organic matter, the fract ion concent ra ted b e i n g d e t e r m i n e d b y the choice of solvent . T h e mos t o b v i o u s l i m i t a t i o n o n the m e t h o d is that set b y so lvent choice , the so lvent s h o u l d have o n l y l i m i t e d so lub i l i t y i n water , w h i c h l im i t s the mater ia l s r e m o v e d to the less p o l a r c o m p o u n d s . A n o t h e r l i m i t a t i o n is that set b y con t amina t i on . T h e so lvent u s e d m u s t be p u r i f i e d carefully, s ince the amoun t s of the v a r i o u s organ ic c o m p o u n d s co l l ec ted f r o m wate r c o u l d be about as large as the trace i m p u r i t i e s i n the solvents . O n c e the separa t ion in to the o rgan ic so lvent has been a c c o m p l i s h e d , any of a n u m b e r of techniques of f rac t iona t ion a n d analys is c a n be a p p l i e d . T h e first step i n the so lvent ex t rac t ion is the ac tual s a m p l i n g of the water. A l l of the p r o b l e m s associated w i t h s a m p l i n g c a n occu r i n this step a n d m a y be aggrava ted b y the large v o l u m e s of wa te r c u s t o m a r i l y e m p l o y e d .
