8. Start each sample run with blank(s) and reference material to
verify proper operation of the instrument. Analyze samples in
sequences of max 20 samples followed by a blank and reference
material. Insert also standards in the sequence to test accuracy
and drift during the analytical runs.
9. Determine concentration in the sample by the slope of the calibration curve.
10. These can be stored in the refrigerator for up to 3 weeks, in the
freezer for up to 6 months.
11. We have used ca. 5–10 different dilution steps for calibration
depending on the concentration span of the samples.
12. This is to prevent contamination of other samples in case of
bubbles forming during measurements.
13. We have a Shimadzu TOC-V CPH with ASI-V autosampler. The
sample is first purged with CO 2 free air to remove inorganic
carbon, and then an aliquot is injected onto a combustion tube
filled with platinum-coated alumina beads. The sample is purged
through the combustion column where non-purgeable organic
carbon compounds are converted to CO 2 , which is detected by a
non-dispersive infrared detector.
14. Using a large filtration device (e.g., 50 mm Ø), you may place
several filters on top of each other, and suck ultrapure water
through the filters.
15. There should be a clear color on the filter but not forming a
“cake” of biomass. The detection limits of the instrument used
to determine the POC should be considered when making the
filtration, and measuring the dry weight first will give you some
idea of how much water you need to filter.
16. This is to minimize the water content as much as possible.
17. Make sure to use lids not closing the Petri dish completely, or
alternatively use some aluminum foil, to let the filter dry
completely. The filter can be stored dry at room temperature
in a desiccator.
18. Marking the sample name with well plate name makes it easy to
follow the samples.
19. We have used Europa Scientific ANCA 20–20 stable isotope
analyzer with a Roboprep-CN biological sample converter.
The combustion tube is filled with Cr 2 O 3 (oxidation catalyst),
CuO wire, and Ag wool. The balls are combusted at 1000
C
to oxidase hydrocarbons, and the gases produced (CO 2 , etc.)
are transferred through a reduction tube for measurement in
the detector of the analyzer.
Determining Carbon Concentration
69
verify proper operation of the instrument. Analyze samples in
sequences of max 20 samples followed by a blank and reference
material. Insert also standards in the sequence to test accuracy
and drift during the analytical runs.
9. Determine concentration in the sample by the slope of the calibration curve.
10. These can be stored in the refrigerator for up to 3 weeks, in the
freezer for up to 6 months.
11. We have used ca. 5–10 different dilution steps for calibration
depending on the concentration span of the samples.
12. This is to prevent contamination of other samples in case of
bubbles forming during measurements.
13. We have a Shimadzu TOC-V CPH with ASI-V autosampler. The
sample is first purged with CO 2 free air to remove inorganic
carbon, and then an aliquot is injected onto a combustion tube
filled with platinum-coated alumina beads. The sample is purged
through the combustion column where non-purgeable organic
carbon compounds are converted to CO 2 , which is detected by a
non-dispersive infrared detector.
14. Using a large filtration device (e.g., 50 mm Ø), you may place
several filters on top of each other, and suck ultrapure water
through the filters.
15. There should be a clear color on the filter but not forming a
“cake” of biomass. The detection limits of the instrument used
to determine the POC should be considered when making the
filtration, and measuring the dry weight first will give you some
idea of how much water you need to filter.
16. This is to minimize the water content as much as possible.
17. Make sure to use lids not closing the Petri dish completely, or
alternatively use some aluminum foil, to let the filter dry
completely. The filter can be stored dry at room temperature
in a desiccator.
18. Marking the sample name with well plate name makes it easy to
follow the samples.
19. We have used Europa Scientific ANCA 20–20 stable isotope
analyzer with a Roboprep-CN biological sample converter.
The combustion tube is filled with Cr 2 O 3 (oxidation catalyst),
CuO wire, and Ag wool. The balls are combusted at 1000
C
to oxidase hydrocarbons, and the gases produced (CO 2 , etc.)
are transferred through a reduction tube for measurement in
the detector of the analyzer.
Determining Carbon Concentration
69