Every water quality result reported on a DMR traces back to a physical sample collected in the field. The chain of custody (COC) is the documented proof that the sample was properly collected, preserved, transported, and analyzed without tampering or error. A broken chain of custody can invalidate otherwise perfect data. Water quality software extends the chain beyond the paper COC form into a complete digital record from field to report.
The Chain of Custody Process
Sample Collection & Labeling
Each sample container receives a unique label before or immediately at collection with:
- Unique sample identification number
- Monitoring location ID
- Date and time of collection
- Sampler’s initials
- Preservative (if pre-preserved) or notation of field preservation
- Analysis requested (if not on the COC form)
Labels must be waterproof, legible, and securely attached. A mislabeled sample is an unrecoverable error — you cannot go back and re-collect that moment in time.
Preservation
Different parameters require different preservation methods applied immediately at collection to prevent sample degradation. Failure to preserve correctly can invalidate results:
| Parameter | Preservative | Holding Time |
|---|---|---|
| Bacteria (E. coli, Total Coliform) | Na₂S₂O₃ + ice, ≤10°C | 6–24 hours |
| BOD | Ice, ≤6°C | 48 hours |
| Ammonia | H₂SO₄ to pH <2, ≤6°C | 28 days |
| Nitrate/Nitrite | H₂SO₄ to pH <2, ≤6°C | 28 days |
| Total Phosphorus | H₂SO₄ to pH <2, ≤6°C | 28 days |
| Dissolved Metals | Field filter + HNO₃ to pH <2 | 6 months |
| Total Metals | HNO₃ to pH <2 | 6 months |
| VOCs | HCl to pH <2, zero headspace, ≤6°C | 14 days |
| TSS | Ice, ≤6°C | 7 days |
| pH, Temperature, DO | None — field measurement | Immediate (15 min) |
COC Form Documentation
The COC form is the legal document that accompanies samples from collection to the laboratory. A complete COC includes:
- Project name/number and client information
- Sampler name and signature
- Each sample ID with collection date, time, and matrix
- Number and type of containers per sample
- Preservatives applied
- Analyses requested per sample
- Turnaround time required
- Relinquished by / received by signatures with date and time for each transfer
- Special instructions (rush, specific methods, reporting requirements)
Transport & Custody Seals
Samples are packed in coolers with ice to maintain temperature and sealed with custody seals across the cooler lid. The seal provides tamper evidence — if the seal is broken on arrival at the laboratory, the integrity of the samples is in question. Each custody transfer (field to courier, courier to lab) requires signatures on the COC form.
Laboratory Receipt
The laboratory logs samples in with a receipt inspection: cooler temperature, custody seal integrity, sample condition, preservation verification (pH check for acid-preserved samples), and reconciliation against the COC form. Any discrepancies are documented as sample receipt exceptions and communicated to the client immediately.
Digital Chain: From Lab to Report
This is where paper COC ends and the digital chain begins. EDD import captures the laboratory’s results with collection date, analysis date, method, and detection limit. Software links the imported data to the sampling event record, validates holding times automatically, and logs every subsequent review, approval, and reporting action with user identity and timestamp.
How Software Extends the Chain of Custody
Sampling Event Records
Software records each sampling event with the monitoring location, date, time, sampler, sample type (grab or composite), and field observations. This digital record links to the physical COC and becomes the anchor point for all subsequent data.
Automated Holding Time Verification
When lab results are imported, software compares the collection date/time from the sampling event to the analysis date/time from the lab EDD. Any result analyzed after its regulatory holding time is automatically flagged with a holding time exceedance qualifier, alerting reviewers that the data may be estimated or invalid for compliance purposes.
Complete Audit Trail
Every action on a data point is logged: initial import, validation flags, reviewer dispositions, approvals, edits, and inclusion in DMR reports. When an auditor asks “show me the history of this result,” software produces a complete chronological record from import through reporting with every user and timestamp documented.
QA/QC Sample Tracking
Field duplicates, equipment blanks, and trip blanks defined in your QAPP are tracked alongside routine samples. Software calculates duplicate RPDs, checks blank results for contamination, and documents QC results as part of the complete data quality record.
Related Ecesis Solutions
Water Quality Software
Lab imports, data validation, permit tracking and DMR reporting.
Inspections & Audits
Mobile field inspections with corrective action tracking.
Document Control
Manage SOPs, permits, and compliance documents.
Compliance Obligations
Track all regulatory obligations and recurring deadlines.
Environmental Data
Sensor integration, statistical analysis and trend visualization.
Task Tracking
Assign corrective actions with due dates and accountability.
Need a Digital Chain of Custody for Your Data?
Call (720) 547-5102 or click below to see how Ecesis tracks data from field to report.
