What this tool does
Turn recorded filter masses into concentrations while keeping the net residue, ignition-loss correction and sample-volume basis visible.
When to use it
After obtaining the tare, dried and ignited masses and the original sample volume from the same gravimetric determination. Do not combine masses from unrelated filters.
Inputs and supported units
Use the labelled laboratory units and a consistent sample basis. Values are not silently interpreted as a regulatory method. Numeric input changes clear earlier results; CSV files are read locally, without uploading. The demonstration values only illustrate the arithmetic.
Calculation or decision method
Convert all masses to mg and the filtered volume to mL. Dry captured mass = dried mass − tare. Corrected volatile mass = dried mass − ignited mass − matching blank ignition loss. Fixed mass = dry mass − corrected volatile mass. Each concentration is mass (mg) × 1000 / filtered volume (mL).
VSS fraction is 100 × volatile mass / dry mass. At zero captured mass it is undefined, not 0%. The minimum-mass comparison is independent of mg/L: a small residue over a small volume can produce a plausible concentration without enough captured mass for the governing method.
How to interpret the result
Read the breakdown, exclusions and input record before the headline. Meeting an entered numeric condition is not a complete analytical quality decision. Retain the original bench sheet and resolve differences with the laboratory reviewer.
Worked example
A 1.1774 g tare, 1.2074 g dried mass, 1.1874 g ignited mass, zero entered blank loss and 100 mL original sample give 30 mg dry residue and 20 mg ignition loss: TSS 300 mg/L, VSS 200 mg/L, fixed fraction 100 mg/L and VSS/TSS 66.6667%.
Assumptions
The entered measurements describe the same stated sample, method and basis. Inputs must already account for any upstream dilution not explicitly modeled. Criteria come from the governing SOP, not from this website.
Limitations
Use appropriately prepared filters and matched weighing/blank conditions from the actual method. This arithmetic does not specify drying or ignition procedures, establish balance performance, select filter media, infer a reporting limit or approve a report. Ignition loss is an operational fraction, not a direct measurement of organic carbon or active biomass. Dissolved solids and settleable volume are different measurements. Reconcile any upstream sample dilution outside this tool.
Sources
- Wisconsin DNR — Laboratory Study Guide
- U.S. EPA — Methods for Chemical Analysis of Water and Wastes (160.2 / 160.4)