12 



analysis (Table 2-1; USEPA 1986). Sediment samples were digested using nitric acid in a 

 microwave oven (Method 3051) except for mercury analysis (Method 7471). Aluminum 

 (Al), cadmium (Cd), chromium (Cr), copper (Cu), iron (Fe), nickel (Ni), and zinc (Zn) were 

 analyzed by inductively coupled argon plasma emission spectrophotometry (ICP, Method 

 6010). Digestates can be heated in several stages allowing removal of unwanted matrix 

 components. Analysis by ICP allows simultaneous or rapid sequential determination of many 

 different metals. The detection threshold associated with ICP analysis is frequently higher 

 than that of atomic absorption spectrophotometry (AAS). Arsenic (As) and lead (Pb) were 

 analyzed using graphite furnace atomic adsorption techniques (GFAA), and mercury (Hg) 

 was analyzed using cold vapor atomic adsorption (CVAA). AAS determinations are 

 completed as single element analyses which allow for low detection limit thresholds. 



2.3.4 PAH Analyses 



All six WLIS samples were analyzed for PAHs using SW-846 Method 8270 (Table 2- 

 1; USEPA 1986). This method determines the concentration of semivolatile organic 

 compounds from a sample extract using a gas chromatograph with a mass spectrometer 

 detector (GC/MS). Detection limits for PAH compounds were within limits suggested for 

 the method. 



Each PAH sample was spiked with three system monitoring or surrogate compounds 

 (2-fluorobiphenyl, nitrobenzene-D 5 , and terphenyl-D 14 ) as a measure of accuracy. Surrogate 

 samples are analyzed as a check on the laboratory's ability to extract known concentrations 

 of compounds not found normally in the sample. All PAH surrogate recoveries were within 

 acceptance limits except for high recoveries of terphenyl-D 14 in all samples except the 

 method blank. The high surrogate recoveries were potentially caused by matrix interference. 

 The acceptable recoveries of two out of three surrogate compounds indicate no laboratory 

 extraction problem (USEPA 1988a). 



Specific QC samples for the PAH analyses included a method blank, a spiked sample, 

 and a spiked duplicate sample. These results are discussed in the QA/QC section below 

 (2.3.6). 



2.3.5 Pesticides and PCB Analyses 



Pesticides and PCBs were analyzed using protocols described in SW-846 Method 

 8080 (Table 2-1; USEPA 1986). This method determines the concentration of various 

 organochlorine pesticide and PCB compounds from a sample extract using a GC/MS. 

 Detection limits for pesticides and PCBs were within limits suggested for the method. 



Each sample analyzed for pesticides was spiked with two surrogates (dibutyl 

 chlorendate and TCMX), and each sample analyzed for PCBs was spiked with TCMX. 



Monitoring Cruise at the Western Long Island Sound Disposal Site, July 1992 



