(CVAA). AA determinations are completed as single element analyses which allow for low 

 detection limit thresholds (the direct aspiration method is not as sensitive as graphite furnace 



AA). 



TOC was measured using protocols described in SW-846 Method 9060 (EPA 1986). 

 Organic carbon in the samples was converted by the analyzer to carbon dioxide (C0 2 ), which 

 was subsequently measured by an infrared detector. The amount of C0 2 is directly 

 proportional to the concentration of carbonaceous material in the sample. Inorganic forms of 

 carbon (carbonate and bicarbonate) are not included as part of the reported total organic 

 carbon value. Total organic carbon is a measurement of organic matter (both labile and 

 refractory) in sediments. 



Composited MBDS samples were analyzed for semivolatile organics using SW-846 

 Method 8080 (pesticides and PCBs) by the NED laboratory, and Method 8270 (basic, 

 neutral, and acidic semivolatiles or BNA) by Chemrox Laboratory Services in Shelton, 

 Connecticut. BNA compounds include a full suite of polynuclear aromatic hydrocarbons 

 (PAHs; Table 2-2). Method 8080 measures the concentrations of several chlorinated 

 pesticides and PCBs from a sample extract using a gas chromatograph with an electron 

 capture detector. Method 8270 measures the concentration of semivolatile organic 

 compounds soluble in methylene chloride using a gas chromatograph with a mass 

 spectrometer detector (GC/MS). 



Chemical Analyses of Sediment Sampling at the Massachusetts Bay Disposal Site, June 1989 



