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Appendix C
5/20/2009
1
Chesapeake Biological Laboratory
University of Maryland Center for Environmental Science
Nutrient Analytical Services Laboratory
Determination of Dissolved Organic Carbon (NPOC), Total Organic
Carbon, and Dissolved Inorganic Carbon in waters of
Fresh/Estuarine/Coastal Waters using High Temperature Combustion
and Infrared Detection
.
1.
SCOPE and APPLICATION
1.1
High temperature combustion (680
°
C) is used to determine dissolved
organic carbon (DOC), also known as non-purge able organic carbon
(NPOC), total organic carbon (TOC), and total (TIC) or dissolved
inorganic carbon (DIC), using a non-dispersive infrared detector
(NDIR). The method is used to analyze all ranges of salinity.
1.2
A Method Detection Limit (MDL) of 0.18 mg/L DOC, and 0.03 mg/L
DIC was determined using 3X the standard deviation of 7 replicates.
1.3
The quantitation limit for DOC and DIC was set at 0.05 mg/L C.
1.4
This procedure should be used by analysts experienced in the theory and
application of organic carbon analysis. Three months experience with
an experienced analyst, certified in the analysis using the organic carbon
analyzer, is required.
1.5
This method can be used for all programs that require analysis of
dissolved and total organic and inorganic carbon.
1.6
This procedure conforms to EPA Method 415.1.
2.
SUMMARY
2.1
The Shimadzu TOC-5000/5000A uses a high temperature combustion method
to analyze aqueous samples for TIC, TOC and non-purge-able organic carbon
(NPOC).
2.2
NPOC samples are treated with hydrochloric acid and sparged with ultra pure
carrier grade air to drive off inorganic carbon. TOC samples are injected
directly onto the catalyst bed with no pretreatment. High temperature
combustion (680
C) on a catalyst bed of platinum-coated alumina balls
breaks down all carbon compounds into carbon dioxide (CO
2
). The CO
2
is
carried by ultra pure air to a non-dispersive infrared detector (NDIR) where
CO
2
is detected.
2.3
Samples for inorganic carbon (TIC) are injected directly into a receptacle of
25% phosphoric acid where the carbonates are reduced to CO
2
and detected by
the NDIR.