Standard Methods; 2540 A, 2540 D, 2540 E

The residue obtained after a thoroughly mixed sample is filtered and dried at 103° -105° C represents the amount of solids suspended in the sample solution. The amount of suspended solids in a water sample may be used as a general indicator of the overall quality of the sample. Suspended solids analyses are important in the control of biological and physical wastewater treatment processes and for assessing compliance with discharge regulations. The residue remaining after drying at 103° C is weighed and placed in a muffle furnace at 550° C. The weight loss from ignition determines "volatile suspended solids".

• Vacuum pump and manifold
• Forceps or tweezers
• Desiccator and desiccant that contains a color indicator for moisture content
• Drying oven for use at 103° -105° C
• Muffle furnace for use at 550° C.
• Analytical balance - capable of weighting to 0.1 mg
• Magnetic stirplate and stirbar
• Magnetic stirbar retriever
• Crucible tongs
• Heat resistant gloves
• Cotton gloves
• Glass-fiber filter disks (Whatman AH-934 or equivalent)
• 40 mL Gooch crucible (permanently labeled)
• Aluminum dish for drying filter disks
• Side arm erlenmeyer flask
• Sample Delivery Mechanisms: (as required)
1. 1 mL - 5 mL variable pipette,
2. 25 mL graduated wide-mouth glass pipette,
3. 50 mL wide-mouth glass transfer pipette, OR
4. 250 mL glass graduated cylinder

Reagents

Distilled or deionized water

 

Storage / Preservation

Samples may be stored in a plastic or glass container and kept for 7 days at 4° C. See sample storage and preservation table in Appendix D of this manual.

Raw Data Sheet Format

The following must be recorded on the data sheet:

• Sample identification (source, name, and date(s) of collection)
• Analyst(s)
• Raw data
• Final results with correct units (reported to nearest mg/L)
• Description of unusual sample characteristics
• Replicates are to be listed in an orderly cluster

Quality Control Requirements

• A check sample should be analyzed with every batch of samples.
• Recoveries of suspended solids check samples should be between ±2σ.
• Recoveries of suspended solids check samples should be between ±3σ.
• Recovery statistics of suspended solids check samples should be reviewed on a yearly basis and any changes in acceptable ranges documented appropriately.
• Results of replicate analyses should yield RSD’s of less than 5% for the set.

Procedure for Total Suspended Solids

Filter Preparation

1. Pre-wash glass-fiber filter disks in Gooch crucibles. With vacuum operating wash the disks with three 20 mL portions of distilled or deionized water.
2. When all water has been vacuumed through the filter disks, place the Gooch crucible in a 103° -105° C oven to dry. If volatile suspended solids are to be analyzed, move the dry filters into a 550° C muffle furnace for 15 minutes; if the volatile portion does not need to be determined, place the crucibles into a desiccator to cool and skip step 3.
3. Remove the Gooch crucibles from the muffle furnace and place on a heat resistant surface. The surface temperature of the crucible must be greater than 103° C when placed into the desiccator.
4. Cool the filters thoroughly in a desiccator before use. Gooch crucibles and washed filters should be stored in a desiccator.

 

Sample Analysis

1. Weigh the Gooch crucible and filter (at room temperature) on an analytical balance. Use crucible tongs or wear lint free cotton gloves to transfer the crucible from the desiccator to the balance pan. Handling the crucible with your bare fingers may transfer oils and moisture from the skin.
2. Record the weight of the crucible and filter.
3. Place prepared crucible and filter on the vacuum manifold or side-arm Erlenmeyer flask with vacuum gasket. Wet the filter with deionized water in order to seat the filter against the crucible. Turn on the vacuum. If there is a hole in the filter, you may hear an abnormal hissing or whistling. Use a different weighed crucible and filter.
4. Thoroughly mix the sample to be analyzed. Carefully measure the volume of sample transferred to the Gooch crucible. The volume of sample used should leave at least 2.5, but not more than 200, milligrams of residue on the filter.
5. Rinse the filter with three successive 10 mL portions of deionized water. If the sample takes excessive time to filter (longer than 10 minutes), begin again with a different weighed crucible and filter using a smaller volume of sample for filtering.
6. Allow the vacuum to continue until no traces of moisture are present. If solids are present on the side of the funnel, rinse the sides gently with deionized water.
7. Place the crucible in the oven to dry for at least 1 hour at 103° C.
8. Transfer the dried crucible to a desiccator to cool. When the crucible has cooled sufficiently it should not feel warm to the touch on the inside of your forearm.
9. Weigh the dried and cooled crucible on an analytical balance. Record the weight. If the sample is not going to be used for regulatory purposes, it may be acceptable to use this weight as the final dry weight.
10. Return the crucible to the drying oven for another thirty minutes. Cool, reweigh and record its weight. Repeat this procedure until the change in the weight of the residue remains within 4% or less than 0.5 mg from one weighing to the next. (This is referred to as constant weight.) Record the final dry weight on the benchsheet and calculate the total suspended solids.

Calculation



Where:







Procedure for Volatile Suspended Solids

1. Place the crucible, filter, and residue produced by TSS analysis in a muffle furnace at a temperature of 550° C for 15 - 30 minutes.
2. Remove crucible with filter and allow to cool partially, then place in a desiccator until cooled.
3. Weigh cooled crucible and filter on an analytical balance and record ashed weight. If the sample is not going to be used for regulatory purposes, it may be acceptable to use this weight as the final ashed weight.
4. Repeat ignition, cooling and weighing until a constant weight is obtained or until weight loss is less than 4% of the previous weight.
5. Record the final ashed weight on the benchsheet and calculate the volatile suspended solids.

Calculation



Where:







 

Goals for a New Analyst Performing TSS / VSS Analyses

• Know safety procedures for solids anlayses
• Know how to fill out raw data sheets
• Know where to find equipment / supplies
• Glass fiber filter circles
• Gooch crucibles
• Suspended solids check samples
• Pipettes and pipette tips
• Understand equipment used to perform solids analyses
• Analytical scales
• Level of sensitivity
• How to tare weights
• Pipettes
• Desiccator
• Muffle furnace
• Understand analysis procedures used to perform solids analyses
• Need for well mixed samples
• Means for taking sample aliquots
• Choice of pipette tip hole size
• Drying times
• Cooling times
• Know how to calculate total and volatile suspended solids results
• Understand quality control procedures
• Need for quality control
• Calculation of percent recovery
• Calculation of mean and %RSD
• Know how to clean crucibles and prepare filters

 

TSS / VSS Analysis; the Tips for Techs version

• Prepare crucibles and filters (if not already done)
• Collect the sample
• Obtain dry weight of crucible and filter (tare weight)
• Place crucible on vacuum system and turn on vacuum system
• Transfer appropriate volume of sample to crucible
• Rinse crucible with deionized water
• Allow vacuum to remove all water
• Place crucible in oven to dry
• Move crucible to desiccator to cool
• Obtain dry weight (constant if necessary) of crucible, filter, and sample residue
• Calculate total suspended solids
• Place crucible, filter, and sample residue into muffle furnace
• Move crucible to desiccator to cool
• Obtain ashed weight of crucible, filter, and sample residue
• Calculate volatile suspended solids
• Prepare crucible and new filter for later use