2540 D – TOTAL SUSPENDED SOLIDS DRIED AT 103-105C Rev 1.0
TOTAL SUSPENDED SOLIDS - SM 2540D
Total Solids: material residue left in a vessel after evaporation of a sample and its subsequent drying in an oven. Total solids include:
Total Suspended Solids: Portion of Total Solids retained by a filter (2.0um or smaller nominal pore size)
Total Dissolved Solids: Portion that passes through the filter
SOURCES OF ERROR
Sampling, subsampling, pipetting multiple phase samples
-Keep samples homogeneous during transfer, and mix small samples by magnetic stirrer
-If suspended solids are present – pipet with wide-bore pipettes
Avoid opening dessicator until ready
Use Type III water for rinsing filters, filtered solids and to clean labware
Analyze samples in duplicate
Dry samples to a constant weight. This entails multiple drying-cooling-weighing cycles for each determination
SAMPLE HANDLING
· Use resistant glass or plastic bottles – as long as material does not adhere to container walls
· Begin analysis ASAP after sampling.
· Refrigerate sample at 4C up to time of analysis
· Do not hold samples more than 24 hrs
· Bring samples to room temperature prior to analysis
Preparation of Glass-Fiber Filter Disk
1) SKIP ENTIRE PROCEDURE IF USING PRE-PREPARED GLASS FILTERS
2) Label bottom of filter with appropriate number/code using a #2 pencil
3) Insert disk with wrinkled side up in filtration apparatus
4) Apply vacuum
5) Wash disk with 3 successive 20-mL portions of reagent grade water
6) Continue suction to remove all traces of water
7) Turn vacuum off
8) Remove filter from filtration apparatus and transfer to aluminium weighing dish
9) Dry in an oven @ 103-105C for 1 hour
10) Cool in a desiccator to balance temperature
11) Weigh
12) Repeat cycle of drying, cooling, desiccating and weighing until a constant weight is obtained, or until weight change is less than 4% of the previous weighing or 0.5mg – whichever is less
13) Store in desiccator until needed
Selection of filter and sample sizes
1) Choose sample volume to yield between 2.5 and 200mg dried residue
2) If volume filtered fails to meet minimum yield, increase sample volume up to 1 L
3) If complete filtration takes more than 10 min, increase filter diameter or decrease sample volume
Sample Analysis Procedure
1) Assemble filtering apparatus & filter
2) Apply vacuum
3) Wet filter with a small volume of reagent grade to seat in apparatus
4) Stir sample with a magnetic stirrer at a speed to shear larger particles
- Centrifugal force may separate particles by size and density, resulting in poor precision when point of sample withdrawl is varied.
5) While stirring, pipe a measured volume onto the seated glass fiber filter.
- For homogeneous samples, pipet from the approximate mid-point of container, but NOT in the vortex
- Choose a point both midpoint and midway between wall and vortex
6) Wash filter with 3 successive 10-mL volumes of reagent grade water, allowing complete drainage between washings
7) Continue suction for about 3 minutes after filtration is complete
- Samples with high dissolved solids may require additional washings
8) Carefully remove filter from filtration apparatus and transfer to an aluminium weighing dish as support.
9) Dry for at least 1-hr at 103-105C in an oven
10) Cool in desiccator to balance temperature and weigh
11) Repeat cycle of drying, cooling, desiccating and weighing until a constant weight is obtained, or until weight change is less than 4% of the previous weighing or 0.5mg – whichever is less
12) Analyze at least 10% of all samples in duplicate
13) Duplicate determinations should agree within 5% of their average weight
14) Analyze an additional 10% of standards/known TDS/TSS???
Calculation
mg total suspended solidsL=A-B x 1000sample volume, mL
Where:
A = Weight of filter + dried residue (mg)
B = Weight of filter (mg)
Apparatus/Materials Required
1) Silica filters
2) Desiccator
3) Drying oven (103-105C)
4) Analytical balance (0.1 mg)
5) Stir-plate
6) TFE stirring bars
7) Wide Bore Pipettes (Kimble #37005 or 37034B or equiv) – OR SEROLOGICAL PIPETTES?
8) Graduated Cylinder – OR SEROLOGICAL PIPETTES
9) Low-form beaker (Class B or better)
10) Glass fiber filter discs without organic binder (see list on pg 2-56)
- Whatman grade 934AH
- Gelman type A/E
- Millipore type A40
- E-D Scientific Specialities grade 161
- Environmental Express Pro Weigh
- Or other products that give demonstrably equivalent results
11) Filter Apparatus
- Fritted disk as filter support
- Gelman No. 4201 or equivalent
12) Suction Flask
13) Aluminium Weighing Dishes
14) Vacuum
15) Reagent grade water