(1991). The elutriates were collected in hexane-rinsed scintillation 

 vials. Toxicity may not have been recovered by methanol extractions 

 because either the toxic compounds or the oil and grease they are sorbed 

 to are highly nonpolar. The methylene chloride was evaporated and the 

 sample restored to volume using methanol. The fractions were tested for 

 toxicity using 150 u^ (microliters), 75 ul , and 37.5 ul of the fraction 

 in 10 ml of dilution water. The methanol concentrations were below the 

 48-hour LC50 for C. dubia, so toxicity was attributed to the nonpolar 

 organic solutes, rather than to the methanol solvent. 



The toxic fractions were sent to Daily Analytical Laboratories in 

 Peoria, Illinois for analysis on a Hewlett-Packard 5890A gas chromato- 

 graph with a 5970A Series mass selective detector along with a 7673A 

 autosampler. The methanol concentrate was injected into a 30-m (meter) 

 x 0.25-mm (millimeter)-i .d. DB-5 J&W capillary column. The temperature 

 program was 40°C for 4 minutes followed by an increase at a rate of 10° 

 C per minute to a peak of 300° C for 10 minutes. Run time was 40 

 minutes with a scan start time at 3 minutes. The peak detection 

 threshold was 10,000 counts, with a threshold at 100 counts. A 

 splitless injection mode was used along with a linear scanning method 

 from 40-450 mhz (megahertz). The samples had 40 ug (micrograms)/ml of 

 internal standards of the following compounds; l,4-Dichlorobenzene-d4, 

 Naphthalene-dS, Acenaphthene-dlO, Phenanthrene-dlO, Chrysene-dl2 and 

 Perylene-dl2. After the sample was analyzed by the mass selective 

 detector, they were compared to library searches using the NIH (National 

 Institutes of Health) EPA (U.S. Environmental Protection Agency) Mass 

 Spectral Database. Identifications were based on the best fit with a 

 minimum search fit of 70%. 



23 



