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SOP6 – Water Quality Analysis
40
7.3.2. Particulate Organic Carbon (POC) analyzed as Particulate Carbon
plus blanks – using NASL filtering protocols
(see Appendix A)
In Chesapeake Bay, particulate carbon analyses actually measure particulate organic carbon
(POC) because the amount of particulate inorganic carbon (PIC) present is not detectable (e.g.,
Fisher et al, 1998). However, MERC filters for PIC analyses at least once per season to validate
this assumption.
Filter whole-water within a few hours. Filter 4-pads for each sample. Using forceps, place a
precombusted 25 mm GF/F filter pad (nominal pore size is 0.7 microns), on the frit and cover
with the cup. Use the vacuum pump suction to help place the pad.
Vigorously shake the sample bottle. Sample rinse an appropriate to-deliver graduated cylinder.
Again, vigorously shake the sample bottle and filter a known volume of water using the to-
deliver graduated cylinder.
Filter until the water is dripping from the filter flask (as opposed to running in a stream). Do not
let the filter suck dry until you have added the full amount of sample water. Once all water is
added, filter to dryness.
Do NOT rinse the funnels until the filters have been removed.
Record the amount filtered on the data sheet. Using forceps and
without touching the filtered
area
, fold filter in half with the material on the inside and place into a labeled foil packet. Rinse
funnels with DI and wipe with Kim wipe. Place foil packet into a labeled bag and freeze.
7.3.2.1. POC Blanks
Using forceps, fold 2 dry, unused precombusted pads in half. Place both into one labeled foil
packet. Freeze along with the samples.
7.3.3. Total Suspended Solids (TSS) – NASL filtering protocols
(see Appendix A)
Filter whole-water within a few hours. Filter each sample for triplicates. Using forceps, place a
pre-weighed and numbered 47 mm GF/F filter pad (nominal pore size is 0.7 microns), pad
number down, on the frit and cover with the cup. Use the vacuum pump suction to help place
the pad.
Vigorously shake the sample bottle. Sample rinse an appropriate to-deliver graduated cylinder.
Vigorously shake the sample bottle and filter a known volume of water using the to-deliver
graduated cylinder.
Filter as much water as possible – until the filtered water is just dripping from the filter flask (as
opposed to running in a stream). Note: Do not let the filter suck dry until you have added the full
amount of sample water. You can stop the filtering if necessary while measuring out more water.
Filter to dryness.
DI rinse twice with 10 ml portions of DI to remove salts. Record the amount filtered on the data
sheet.