Overview
Samples are the foundation of every laboratory result. If samples are collected incorrectly, mislabeled, contaminated during transport, or stored at the wrong temperature, no amount of analytical precision can rescue the data. ISO/IEC 17025:2017 addresses this through two complementary clauses: Clause 7.3 covers sampling (when the lab performs it), and Clause 7.4 covers the handling of test items from the moment they arrive at the lab through retention and eventual disposal.
This skill builds both procedures in tandem. For labs that perform field sampling, it creates statistically grounded sampling plans with defined locations, equipment, preservation requirements, and chain-of-custody controls. For all labs, it produces a comprehensive test item handling procedure covering receipt and registration, unique identification (LIMS integration, barcoding), condition assessment on arrival, handling to prevent cross-contamination, matrix-specific storage requirements, preparation protocols, and retention/disposal policies.
The two extension tools validate each procedure independently, so labs that do not perform sampling can mark Clause 7.3 as out of scope and focus entirely on the item handling procedure.
What It Covers
- Sampling plans – methodology with statistical basis, sampling locations and points, equipment and containers, preservation and transport conditions
- Chain of custody – unbroken custody tracking from field collection to laboratory receipt
- Field measurements – on-site observations and measurements recorded during sampling
- Sample receipt and registration – intake process, LIMS entry, date/time stamping
- Unique identification – laboratory numbering system, barcodes or labels, sub-sample tracking
- Condition assessment – inspection on receipt, anomaly detection and reporting, acceptance/rejection criteria
- Handling instructions – matrix-specific handling to prevent damage, contamination, or deterioration
- Storage conditions – temperature-controlled storage, segregation, environmental monitoring
- Preparation – sub-sampling, homogenization, extraction, digestion procedures
- Retention and disposal – defined retention periods, disposal methods, return-to-customer procedures
- Confidentiality – protecting customer identity and sample information
Example Conversation
You: We need sampling and sample handling procedures for LabTech Analytical. We do some field sampling for drinking water clients – mostly grab samples from distribution systems and wells. But about 70% of our work is samples that clients drop off or ship to us. We test drinking water, groundwater, and soil.
Agent: Good – so we need both the Clause 7.3 sampling plan (for your field work) and the Clause 7.4 item handling procedure (for everything). Let me start with sampling. A few questions:
- What sampling standards do you follow? EPA methods have specific container, preservation, and hold-time requirements.
- How many field sampling staff do you have, and are they trained to specific protocols?
- Do you use any field instrumentation (pH, temperature, dissolved oxygen, conductivity)?
You: We follow EPA sampling guidance from the Field Sampling Manual. We have 3 samplers – all trained, but we don’t have formal training records for the sampling piece (we know, that’s a problem). Field instruments: YSI ProDSS for temp, pH, DO, and conductivity. Containers are pre-preserved 500 mL HDPE for metals (HNO3 to pH<2), 250 mL plastic for anions (none), and amber glass for anything organic if we ever get into that.
Agent: The training gap is a real finding that will come up in accreditation – but that’s the personnel competence skill’s territory. For sampling, I’ll document the current protocol. For the statistical basis of your sampling plan:
- Drinking water distribution: are you sampling at pre-defined compliance monitoring points set by the state, or do you choose locations?
- Groundwater: are you sampling monitoring wells at set locations for compliance programs?
You: Distribution system samples are at fixed compliance points designated by TCEQ – we just go to the tap locations they specify. Groundwater wells are also fixed locations, usually 3-5 wells per site, quarterly.
Agent: So the sampling plan design is driven by regulatory requirements rather than statistical sampling theory. That’s fine and common – I’ll document the rationale as “regulatory-mandated sampling locations per TCEQ compliance monitoring requirements” rather than inventing a statistical justification that doesn’t apply.
Now for the item handling side. When a client drops off samples at your lab:
- Who receives them?
- How do you assign lab IDs?
- Do you check temperature on arrival?
You: Our sample receiving coordinator, Lisa, handles intake. She logs them in our Element LIMS – it auto-generates a work order number like WO-2024-0847 and individual sample IDs like WO-2024-0847-001. She checks cooler temp with an IR thermometer and notes it. If it’s above 6C for waters that need refrigeration, she flags it but we still run the samples – we just note the deviation on the report.
Agent: Good. I’ll need to build a formal anomaly decision tree for that temperature exceedance scenario. Clause 7.4 requires you to decide: do you proceed with a deviation note, do you contact the client, or do you reject the sample? The answer might depend on how far above 6C it was and what the test is.
I’ve drafted both procedures. Running validation tools…
sampling_plan_validatorresult – REVIEW:
- MISSING: No field measurements/observations section
I’ll add the section documenting YSI ProDSS field measurements (temp, pH, DO, conductivity) that your samplers record at each collection point.
After correction –
sampling_plan_validator: PASS
item_handling_procedure_checkerresult – PASS. All required elements are documented.Both procedures saved to
output/.
Sample Output Excerpt
The skill produces a sampling procedure and a test item handling procedure. Here is a representative excerpt from the item handling procedure.
3. Sample Receipt and Registration
3.1 Receipt Process
Upon arrival of samples at LabTech Analytical, the Sample Receiving Coordinator shall:
- Log arrival: Record date, time, and delivery method (client drop-off, courier, field sampler return) in Element LIMS
- Verify chain of custody: Compare COC form against containers received; note any discrepancies
- Assess condition: Inspect containers for damage, leakage, or insufficient volume; check preservation (pH < 2 for metals, absence of headspace for VOCs if applicable)
- Measure temperature: Record cooler temperature using calibrated IR thermometer (Fisher Scientific Traceable, Cal. ID T-031). Acceptance criterion: less than or equal to 6.0 C for samples requiring refrigeration
3.2 Unique Identification
| Element | Format | Example |
|---|---|---|
| Work order number | WO-YYYY-NNNN | WO-2024-0847 |
| Sample ID | WO-YYYY-NNNN-SSS | WO-2024-0847-001 |
| Sub-sample ID | WO-YYYY-NNNN-SSS-XX | WO-2024-0847-001-A1 (acid digest aliquot) |
Labels are printed from Element LIMS and affixed to each container immediately upon registration. Barcode labels enable scanning at every custody transfer point within the laboratory.
3.3 Condition Assessment and Anomaly Handling
| Anomaly | Action | Notification |
|---|---|---|
| Temperature > 6.0 C but less than or equal to 10.0 C | Accept with deviation; note on COC and report | Client notified via email within 4 hours |
| Temperature > 10.0 C | Contact client before proceeding; document decision | Client contacted immediately by phone |
| Broken or leaking container | Reject affected container; request resample | Client notified same day |
| Insufficient volume | Prioritize analyses per client direction | Client contacted for prioritization |
| Missing preservation | Add preservative if within hold time; document | Noted on report as lab-preserved |
| COC discrepancy | Resolve with client before analysis begins | Client contacted for clarification |
6. Retention and Disposal
6.1 Retention Periods
| Sample Type | Retention Period | Storage Conditions |
|---|---|---|
| Drinking water (regulatory compliance) | 30 days after report issuance or per state requirement | 4 +/- 2 C, segregated by work order |
| Groundwater (site investigation) | 60 days after report issuance | 4 +/- 2 C |
| Soil samples | 60 days after report issuance | Room temperature, sealed containers |
| Extracts and digests | 30 days after analysis or per method requirement | Per method (refrigerated or frozen) |
Extension Tools
sampling_plan_validator
Validates sampling documentation for Clause 7.3 compliance. If sampling is declared out of scope, verifies that a customer responsibility statement is present.
| Check | What It Validates | Severity |
|---|---|---|
| Sampling method | Reference to the sampling method or standard used | MISSING if absent |
| Statistical basis | Justification for sample sizes and selection (statistical or regulatory) | MISSING if absent |
| Sampling locations | Defined sampling points, sites, or stations | MISSING if absent |
| Equipment and containers | Sampling equipment and container types specified | MISSING if absent |
| Preservation | Sample preservation and transport conditions | MISSING if absent |
| Chain of custody | Custody tracking from collection to laboratory | MISSING if absent |
| Field measurements | On-site measurements and observations recorded | MISSING if absent |
| Sampling records | Template for documenting sampling activities | MISSING if absent |
item_handling_procedure_checker
Validates the test item handling procedure for Clause 7.4 compliance.
| Check | What It Validates | Severity |
|---|---|---|
| Receipt and registration | How items are received and registered on arrival | MISSING if absent |
| Unique identification | System for uniquely identifying items throughout lifecycle | MISSING if absent |
| Condition assessment | Inspection and condition recording on receipt | MISSING if absent |
| Anomaly reporting | Procedure for handling discrepancies or damage | MISSING if absent |
| Handling instructions | Measures to prevent damage, contamination, deterioration | MISSING if absent |
| Storage conditions | Temperature, humidity, segregation requirements | MISSING if absent |
| Preparation | Sub-sampling, homogenization, extraction, or digestion | MISSING if absent |
| Retention policy | How long items are retained after testing | MISSING if absent |
| Disposal/return | How items are disposed of or returned to customers | MISSING if absent |
| Confidentiality | Protection of customer identity and sample information | MISSING if absent |
Getting Started
Start by activating the ISO 17025 Sampling & Test Item Handling skill. The agent will first ask whether your laboratory performs field sampling (Clause 7.3) or only receives samples from customers. This determines whether a sampling plan is needed or can be marked out of scope.
Have this information ready:
- Whether your lab performs field sampling, and if so, what sampling standards you follow
- Your sample types (drinking water, groundwater, wastewater, soil, etc.)
- Your LIMS system and how lab IDs are assigned
- Current sample receiving process – who does it, what they check, how they handle anomalies
- Container types and preservation requirements for each matrix/method combination
- Storage conditions and capacity (refrigerators, freezers, ambient storage areas)
- Current retention periods and disposal practices
- Any chain-of-custody forms or templates already in use
If you have already completed the ISO 17025 Laboratory Profile skill, the agent will use your scope of accreditation to tailor sample types, preservation requirements, and handling instructions to your specific methods.