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Detection Limits


USFS/USGS Air Program Laboratory and U.S. EPA Methods*
Instrument Detection Limits**
2012

Analyte
USFS/USGS (mg/L)
EPA (mg/L)*
Na
0.02
0.01
NH4
0.01
0.01
K
0.01
0.01
Mg
0.01
0.01
Ca
0.04
0.01
F
0.01
0.005
Cl
0.02
0.01
NO2
0.07
0.01
NO3
0.03
0.005
SO4
0.04
0.05

*U.S. Environmental Protection Agency, 1987 Handbook of Methods for Acid Deposition Studies: Laboratory Analysis for Surface Water Chemistry. USEPA Acid Deposition and Atmospheric Research Division, Office of Research and Development, Washington, D.C. 20460.

**As per the EPA, the detection limit is defined as three times the standard deviation of 10 nonconsecutive reagent or calibration blank analyses. If a signal is not produced, then a low-concentration standard can be analyzed. Differences between Air Program Lab and EPA detection limits listed above may be due to differences in instrument settings for analysis or type of instrument, for example ion chromatography for cations by Air Program Lab instead of inductively coupled plasma (ICP) or Atomic absorption (AA).