1. Preserve the original observation
Keep sample and bottle IDs, collection/analysis context, analyst records, the actual method revision, units, qualifiers, volumes, masses and raw readings. A copied number without its reporting basis is not a complete input. These local tools do not store a durable laboratory record; save the reviewed output alongside the original bench sheet.
2. Select the right reduction
BOD uses DO depletion and a sample fraction; TSS/VSS uses measured residue masses and filtered volume. They describe different properties and cannot be converted into each other. For BOD, choose directly seeded bottles, seeded dilution water or no seed only when that geometry matches the bench record.
3. Reconcile units and dilution once
Distinguish grams from milligrams and mL from L. Record whether a reported concentration is the final instrument solution, a diluted bottle, or already corrected to original sample. Do not multiply by a dilution factor twice. In the spike calculator, a final-mixture result belongs in physical-volume mode; an already corrected original-sample-equivalent result belongs in matched-basis mode.
4. Keep numerical exclusions visible
A failed DO check, impossible mass order, malformed CSV or censored concentration is information, not an invitation to silently replace it. The BOD analyzer retains scientifically nonqualifying bottles; malformed data produces an error. The RPD checker retains nondetects as not assessed and never inserts zero or half the reporting limit.
5. Review precision separately from recovery
Two duplicate values may agree closely while both are biased. RPD tests their agreement; a matrix spike investigates recovery of an addition. Neither establishes a complete method outcome. Use the project's concentration-sensitive criteria and review the remaining method QC before accepting any result.
6. Retain a review packet
Copy or print the current result, entered inputs, units, modes, comparison limits and URL. Link it to the original sample/method record. Record who reconciled an exclusion, what was investigated and which approved method governs reporting. Do not replace an official LIMS, chain-of-custody record or authorized laboratory report with a browser summary.
Worked review
Two concentrations of 10 and 12 mg/L have RPD 18.1818%. That satisfies an illustrative entered 20% precision limit. A separate matched-basis spike case of native5, spiked14.6 and addition10 mg/L gives96% recovery. These two numerical observations answer different questions; neither proves the sample is safe, the field sample representative or the batch reportable.
Stop and escalate
Ask the qualified reviewer when identities or dilution bases differ, seed controls do not qualify, ash/filter behavior is unexplained, a censor qualifier is not supported, recovery is implausible or the method's rules differ from this tool. Testing procedures, preservation, hazardous reagents, biological material and furnace work remain outside these pages.
Sources
- Wisconsin DNR — BOD Seed: direct bottles and seeded dilution water
- Wisconsin DNR — Laboratory Study Guide
- U.S. EPA — Methods for Chemical Analysis of Water and Wastes (160.2 / 160.4)
- USGS — Design, Analysis, and Interpretation of Field Quality-Control Data
- U.S. EPA — Duplicate Relative Percent Difference definition
- Thermo Fisher Scientific — Why and How to Matrix Spike