The digestion, extraction, and fractionation schemes were similar to 

 those developed by Warner (1976) except that the digestion was performed 

 using a 0.5 N KOH/distilled water/distilled methanol system heated in a 

 boiling water bath for 4 hours to achieve complete digestion and hence 

 release of hydrocarbons from the cellular matrix. Internal standards 

 were added prior to digestion and carried through the entire procedure 

 (f, = androstane; f„ = hexaethyl benzene). Standards were also added to 

 sediment and sediment trap samples (see below). The digestate was 

 extracted three times with distilled hexane in the centrifuge tube. The 

 extracts were combined, concentrated to 0.5 ml, weighed on a Cahn electro- 

 balance, and fractionated on an alumina over silica gel column (Boehm, 

 1978). Two fractions corresponding to the aliphatic or f, (hexane 

 eluate) and the aromatic/olef inic or f (methylene chloride eluate) 

 hydrocarbons were obtained for gas chromatographic analysis. 



Sediment samples were extracted using the method of Boehm and Quinn 

 (1978) and fractionated as stated above. Sediment trap samples (~1 gram) 

 were extracted in closed centrifuge tubes with a methanol-hexane solvent 

 mix in a boiling water bath for 4 hours. The solvent was obtained, 

 concentrated, and fractionated as stated. 



Chromatographic fractions were concentrated to 50 pi and a 1 pi 

 subsample was injected into a Hewlett Packard Model 5840A gas chromato- 

 graph equipped with a flame ionization detector. Samples were chromato- 

 graphed in the splitless injection mode on a 15-m (0.25-mm i.d.) SE-30 

 glass capillary column (J and W Scientific; "^50,000 theoretical plates). 

 The column oven was temperature programmed from 60 C to 275 C at 3 C 

 per minute. The injection port and detector temperatures were 250 C 

 and 300 C, respectively. Peak areas were obtained using a digital 

 integration option which resets the baseline at every valley. Thus peak 

 areas above the unresolved complex mixture (UCM) or hump were digitized. 

 Peak area and retention time information for the sample peaks and the 

 internal standard was transmitted using an HP 18861 digital interface to 

 a PDP 10 computer which computed retention index and quantitative data 

 according to programs developed at ERCO. 



224 



