Selecting and handling standard solutions

Why this decision needs structure

A standard solution links instrument response to a known value. A selection, dilution, storage, or labelling error can affect every result calibrated with that solution.

This guide does not replace an official method, risk assessment, manufacturer instruction, or applicable regulation. Use the cited sources as a starting point, then adapt decisions to the application, laboratory capability, and local requirements. The intended output is a requirements record that can be reviewed, tested, and updated.

A practical decision framework

Value and uncertainty

Record certified value, units, calculation basis, uncertainty, and contribution to the final result. Treat this as a decision that can be verified, not a preference. Record the starting condition, acceptable value or limit, the person who confirms it, and the evidence required. Connect the decision to the method, safety, workload, and post-implementation work. Mark missing information as an open assumption so users, procurement, facilities, and suppliers do not interpret it differently.

Traceability and documents

Record producer, reference material, characterization method, certificate, lot, validity, and document revision. Begin with evidence from real work, then separate mandatory needs from features that merely add convenience. Examine the effect on results, time, user competence, space, utilities, and recurring cost. Each conclusion should have a source, an owner, and a verification method so that later changes can be reviewed without reopening the entire discussion.

Matrix and compatibility

Record solvent, acid, preservative, species, container, concentration, and compatibility with sample and method. Consider normal operation, peak demand, credible failures, and conditions after future change. An agreement that works in only one scenario is fragile. Use numbers where available, state units and tolerances, and retain the decision rationale. This helps the team distinguish risks that require control from features that do not create practical value.

Dilution

Record volumetric apparatus, gravimetric technique, temperature, dilution factor, sequence, mixing, and verification. Treat this as a decision that can be verified, not a preference. Record the starting condition, acceptable value or limit, the person who confirms it, and the evidence required. Connect the decision to the method, safety, workload, and post-implementation work. Mark missing information as an open assumption so users, procurement, facilities, and suppliers do not interpret it differently.

Storage and use

Record temperature, light, opening, contamination, evaporation, stabilization time, and open-container limit. Begin with evidence from real work, then separate mandatory needs from features that merely add convenience. Examine the effect on results, time, user competence, space, utilities, and recurring cost. Each conclusion should have a source, an owner, and a verification method so that later changes can be reviewed without reopening the entire discussion.

Labels and records

Record identity, concentration, units, matrix, preparer, dates, storage, and link to the analytical batch. Consider normal operation, peak demand, credible failures, and conditions after future change. An agreement that works in only one scenario is fragile. Use numbers where available, state units and tolerances, and retain the decision rationale. This helps the team distinguish risks that require control from features that do not create practical value.

Applying the framework to real work

A high-concentration standard may be stable and economical but require several dilution stages. Each step adds uncertainty and contamination opportunity, so the starting concentration should be chosen with the actual workflow in mind. Use a case like this in a short working session with users, method owners, facilities, safety, procurement, and technical support. Put known data beside open questions. This allows different expectations to be resolved before they become quotation revisions, rework, or downtime.

Maintain one decision table with requirement, rationale, evidence, acceptance limit, owner, and status. Do not combine facts, assumptions, and preferences in one sentence. When new information appears, update the relevant row and note its effect elsewhere. This simple discipline makes evaluation transparent and reduces dependence on meeting memory.

Mistakes to avoid

• Starting with a product name or feature list before agreeing the purpose and performance boundary.
• Using words such as good, complete, fast, or suitable without an acceptance measure.
• Ignoring user work, site conditions, recurring materials, documentation, and support after installation.
• Leaving decisions in conversation without a controlled document, owner, and review date.

Action checklist

• Value and uncertainty suit the method
• A current certificate is available
• The standard matrix is compatible with the application
• Dilutions use suitable apparatus
• Calculations receive an independent check
• Storage and use period are defined
• Labels and records trace to results

Bringing the decision together

A strong decision record need not be long, but it should connect the requirement, risk, evidence, and acceptance method. Start with the laboratory work, involve the right roles, and use data to narrow the options. When conditions change, revisit the documented rationale and limits rather than repeating an earlier choice by habit.

Implementation note

Before approval, arrange a cross-review by someone who did not prepare the first draft. Ask the reviewer to find missing units, limits that cannot be tested, terms with more than one interpretation, and dependencies without owners. Confirm that the requirement still matches the current method, workload, building conditions, user capability, and safety policy. Record the review outcome and next review date so the document remains active. If a change affects result quality or risk, reassess it before work continues.

Sources

1. About NIST Standard Reference MaterialsNational Institute of Standards and Technology
2. ISO/IEC 17025:2017 - General requirements for the competence of testing and calibration laboratoriesInternational Organization for Standardization
3. ISO 4787:2021 - Laboratory glass and plastic ware - Volumetric instrumentsInternational Organization for Standardization