The minimum detectable concentration (MDC) is used to assess measurement process capabilities. The MDC indicates the ability of the laboratory to detect an analyte in a sample at desired concentration levels. The ESER requires that the laboratory be able to detect radionuclides at levels normally expected in environmental samples, as observed historically in the region. These levels are typically well below regulatory limits. The MDC is instrument and analysis specific, and is established by the analytical laboratory at the beginning of each analytical run.
|
Sample Type |
Analysis |
Approximate Minimum Detectable Concentrationa (MDC) |
Derived Concentration Guideb (DCG) |
|
Air (particulate filter)e |
Gross alphac |
8.8 x 10-16 µCi/mL |
2 x 10-14 µCi/mL |
|
Gross betad |
1.7 x 10-15 µCi/mL |
3 x 10-12 µCi/mL |
|
|
Specific gamma (137Cs) |
1.3 x 10-12 µCi/mL |
4 x 10-10 µCi/mL |
|
|
238Pu |
1.6 x 10-18 µCi/mL |
3 x 10-14 µCi/mL |
|
|
239/240Pu |
1.1 x 10-18 µCi/mL |
2 x 10-14 µCi/mL |
|
|
241Am |
1.5 x 10-18 µCi/mL |
2 x 10-14 µCi/mL |
|
|
90Sr |
5.4 x 10-17 µCi/mL |
9 x 10-12 µCi/mL |
|
|
Air (charcoal cartridge)e |
131I |
1.2 x 10-15 µCi/mL |
4 x 10-10 µCi/mL |
|
Air (atmospheric moisture)f |
3H |
1.1 x 10-7 µCi/mL |
1 x 10-7 µCi/mL |
|
Air (precipitation) |
3H |
1.1 x 10-7 µCi/mL |
2 x 10-3 µCi/mL |
|
Milk |
131I |
0.5 pCi/L |
-- |
|
|
137Cs |
2.9 pCi/L |
-- |
|
Game Animal Tissueg |
137Cs |
4.3 pCi/kg |
-- |
|
a The MDC is an estimate of the concentration of radioactivity in a given sample type that can be identified with a 95 percent level of confidence and precision of plus or minus 100 percent under a specified set of typical laboratory measurement conditions. b DCGs, set by the DOE, represent reference values for radiation exposure. They are based on a radiation dose of 100 mrem/yr for exposure through a particular exposure mode such as direct exposure, inhalation, or ingestion of water. c The DCG for gross alpha is equivalent to the DCGs for 239,240Pu and 241Am. d The DCG for gross beta is equivalent to the DCGs for 228Ra. e The approximate MDC is based on an average filtered air volume (pressure corrected) of 570 m3/week. f The approximate MDC is expressed for tritium (as tritiated water) in air, and is based on an average filtered air volume of 39 m3, assuming an average sampling period of eight weeks. g The approximate MDC assumes a sample size of 500 g. |
|||