Protocol for University of Washington Bothell Science Labs
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Written by: Christy Cherrier
Updated by: Christy Cherrier
Updated by: Christy Cherrier
Date: October 27, 2003
Date: February 23, 2005
Date: February 28, 2007
This procedure is used to measure total suspended solids or ash-free dry mass of water and algae samples collected on 0.7
µm pore size glass fiber filters.
American Public Health Association, American Waterworks Association, and Water Pollution Control Federation. 1981.
Standard methods for the examination of water and wastewater, 15 th ed. American Public Health Association.
Water samples should be refrigerated after collection.
0.01 mg
 0.7 µm pore size glass fiber filters (Whatman GF/F)
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Small plastic bags
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Aluminum weighing pans
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Forceps
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Metal tray
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Drying oven
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Muffle furnace
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Dessicator
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Analytical or microbalance (at least 5-place)
Wear insulated gloves when removing filters from a hot muffle furnace.
1.1
If measuring ash free dry mass, first, ash the filters. Remove the glass fiber filters from their box (you can do 100 at a time), wrap them in a double thickness of aluminum foil, and place them on a shelf in the muffle furnace. Ash the filters in the muffle furnace for 4 hours at 500ºC.
1.2
Allow the muffle furnace to return to room temperature and remove the filters.
Note: Steps 1.1 and1.2 can be skipped if you are not measuring ash free dry mass.
1.3
Filter ~50mL deionized water through each filter. Place the washed filters on a metal tray and dry them in a drying oven at ~50ºC for at least one hour.
1.4
If the filters will be used for measuring total suspended solids (TSS), weigh each filter to at least the nearest 0.01 mg then transfer the filter to a labeled aluminum pan. Record the pan number and weight.
If the filters will be used only for Ash-Free Dry Mass (AFDM), they do not need to be pre-weighed.
They can be returned to their original box after they have been ashed.

Protocol for University of Washington Bothell Science Labs
Page 2 of 3
Note: Always use forceps to handle filters, never your fingers.
2.1
Filter a known amount of sample through a filter. Use a pre-weighed filter for TSS or an ashed filter if measuring AFDM only. Record the volume of sample filtered and, for TSS only, the filter number.
2.2
Using forceps, carefully fold the filter in half, keeping the material on the inside of the fold. For TSS, replace the filter back into the labeled pan it came from. For AFDM only, place the folded filter into a plastic bag labeled with the sample name.
2.3
2.4
Dry the filters in a drying oven at ~50ºC for several hours, until completely dry.
If the filters will not be analyzed immediately, transfer the pans to a dessicator until they are analyzed.
3.1
Weigh each filter to at least the nearest 0.01 mg and record the sample name and weight. For TSS, also record the filter number. Transfer the filter to a labeled aluminum weighing pan.
3.2
Place weighing pans on a shelf in the muffle furnace. Do not place the pans directly on the bottom of the muffle furnace or the filters will melt. Ash the filters at 500ºC for 4 hours.
3.3
Allow the muffle furnace to cool to at least 150ºC, then, remove the weighing pans. Place them in a dessicator until they reach room temperature. Weigh each filter to at least the nearest 0.01 mg and record the weight on the same data sheet as the weight before combustion. If the filters are allowed to cool completely in the muffle furnace, dry them for ~2 hours in the drying oven before weighing them.
Note: If filters are to be used for particulate phosphorus analysis, after step 3.4, use forceps to carefully transfer the filters to labeled 50-mL digestion tubes and cover with Teflon-lined caps. They may also be stored in their weighing pans in the dessicator if necessary.
3.4
Calculate the total suspended solids or dry mass with the following equation: mg total suspended solids or dry mass/L = (A – B) x 1000
sample volume, mL where:
A = weight of filter + dried residue before ignition, mg
B = weight of filter, mg
3.5
Calculate the volatile suspended solids or ash-free dry mass with the following equation: mg volatile solids or ash-free dry mass/L = (A – C) x 1000
sample volume, mL where:
A = weight of filter + dried residue before ignition, mg
C = weight of filter + residue after ignition, mg

Protocol for University of Washington Bothell Science Labs
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3.6 Calculate the fixed solids with the following equation: mg fixed solids/L = (C – B) x 1000
sample volume, mL where:
C = weight of residue + filter after ignition, mg
B = weight of filter, mg