A measure of whether the analytical procedure is sufficient to detect the analytes 
at environmental levels of concern is the Method Detection Limits (MDLs). Approved 
laboratories were expected to perform in general accord with the target MDLs presented 
for NCA analytes (Table A7-2 in U.S. EPA, 2001). Because of analytical uncertainties 
close to the MDL, there is greater confidence with concentrations above the Reporting 
Limit (RL), which is the concentration of a substance in a matrix that can be reliably 
quantified during routine laboratory operations. Typically, RLs are 3 to 5 times the MDL. 
In these analyses, concentrations between the MDL and the RL were included in the 
generation of mean values for the analyte, while any values below the MDL were set to 
0 . 
A post-analysis assessment of the success of the analytical laboratories in 
meeting NCA QA/QC requirements was conducted by the QA manager of the Western 
Ecology Division, which is summarized here. 
2.4.2 Metals in Sediments 
The analytical methods for metals by the three states are those used in the 
NOAA NS&T Program (Lauenstein and Cantillo, 1993) or documented in the EMAP 
Laboratory Methods Manual (U.S. EPA, 1994). The recommended MDL (Table A7-2 in 
U.S. EPA, 2001) varies by metal, ranging from 0.01 pg/g for mercury to 1500 pg/g for 
aluminum. All three states met the MDL requirements for all the metals. The percent 
recovery from certified/standard materials, recovery from matrix spikes, and the average 
RPD for non-zero sample duplicates and matrix spikes for the sediment metals are 
summarized in Appendix Table 1.1. All three states met all the overall quality 
assurance requirements for metals. While Oregon met the overall requirements, the 
relative accuracy for chromium, nickel, and tin ranged from 22% to 41% compared to 
the requirement of 20% for metals. 
2.4.3 Organics in Sediments 
As with the metals, the analytical methods for organic compounds are those used 
in the NOAA NS&T Program (Lauenstein and Cantillo, 1993) or documented in the 
EMAP Laboratory Methods Manual (U.S. EPA, 1994). The recommended MDL (Table 
A7-2 in U.S. EPA, 2001) is 10 ng/g for PAH compounds and 1 ng/g for the PCBs, DDTs, 
and chlorinated pesticides. All three states met the MDL requirements for all the 
organic compounds. 
The percent recovery from certified/standard materials, recovery from matrix 
spikes, and the average RPD for non-zero sample duplicates and matrix spikes for the 
sediment PAHs are summarized in Appendix Table 1.2. California met the 
requirements for the percent deviation from reference materials but slightly exceeded 
the RPD requirement among duplicate samples (33% vs. 30%). Washington slightly 
exceeded the requirement for the average deviation from reference materials (32% vs. 
30%) but met the requirements for the number of PAH analytes within +35% of the true 
value as well as the requirements for percent recovery from spiked sediment and the 
RPD of duplicates. While failing some of the requirements, the differences were 
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