Customized PT Assurance Model
Proficiency testing (PT) is one of the most effective ways for a laboratory to demonstrate the reliability of its results in an independent and impartial manner. Accreditation standards such as ISO/IEC 17025 and ISO 15189 require laboratories to participate in proficiency testing on a regular basis.
However, many laboratories struggle to find a PT program that truly aligns with their scope of work. Common challenges include matrix mismatches, limited analyte lists, concentration ranges that do not reflect routine operating conditions, or PT round schedules that do not align with their audit plans.
At PT Nexus, we have developed the Custom PT Assurance Model to address this gap. Rather than forcing your laboratory to fit into an off-the-shelf program, our model is designed to fit your laboratory's specific requirements.
What Is the Custom PT Assurance Model?
The Custom PT Assurance Model is a fully tailored, end-to-end proficiency testing service—designed, implemented and reported in line with your laboratory's scope, analytical methods, sample matrices and quality objectives. It is based on the requirements of ISO/IEC 17043 for proficiency testing providers and the statistical methods outlined in ISO 13528, while allowing every stage to be shaped around your real needs.
In short, a standard PT program takes a "one-size-fits-all" approach, whereas the Custom PT Assurance Model is tailor-made for your laboratory.
1. Needs Analysis & Scope Design
The process starts with a technical review with your laboratory. Your accreditation scope, applied methods, target measurement uncertainty, customer and regulatory requirements, and past PT performance are evaluated together. Based on this analysis, we define exactly which analytes will be tested—in which matrices, at which concentration levels, and how often.
2. Program-Specific Test Material
Test materials are prepared to represent your routine samples. For each batch, homogeneity and stability studies are performed in accordance with ISO 13528. This ensures that any deviation in results originates from the measurement process—not the sample.
3. Flexible Round Planning & Logistics
The round schedule is aligned with your audit dates, internal audit plan, and workload. Logistics such as cold chain management, stability windows, and customs requirements are planned in advance.
4. Fit-for-Purpose Statistical Evaluation
The performance evaluation approach (z-score, z′-score, zeta-score, Eₙ number) and the method for assigning values (reference value, formulation, expert laboratory consensus, or participant consensus) are selected based on the program design. In customized programs with a limited number of participants, robust statistical techniques and reference laboratory support are used to maintain evaluation reliability.
5. Clear, Action-Oriented Reporting
Reports go beyond “pass/fail.” They interpret your results by comparing them across method groups, instrument types, and previous rounds. Each report is structured so the quality manager can use it directly in management review.
6. Root Cause Analysis & Corrective Action Support
For results triggering warning or action signals, our technical team guides your laboratory through root cause analysis. The goal is not merely to close a nonconformity—but to prevent recurrence.
7. Ongoing Monitoring & Trend Analysis
Performance is monitored throughout all rounds, and trends in bias and precision are visualized. This helps identify issues before they turn into “unsatisfactory” outcomes.
Who Is It Suitable For?
- Accredited laboratories working with rare or niche analytes and matrices where no suitable market program exists
- Laboratory networks, holdings, and public institutions seeking to compare multiple sites under a single program
- In-house quality control laboratories tailored to production processes (food, pharma, environment, petrochemical, cosmetics, mining, etc.)
- Laboratories validating new methods, expanding scope, or preparing for accreditation
- Organizations needing demonstrable performance evidence for specific parameters due to regulatory requirements
What It Delivers to Your Laboratory
- Realistic, acceptable PT evidence covering your full accreditation scope
- Meaningful performance data through samples reflecting your routine conditions
- Predictable planning aligned with your audit calendar
- Fast, effective corrective action enabled by expert interpretation
- Objective measurement of inter-laboratory alignment within your organization
- Full confidentiality via coded participant identifiers
The Foundation of Trust: Impartiality & Confidentiality
In the Customized PT Assurance Model, each participant is identified by a unique code, and results are shared only with the relevant laboratory. Program design, test material production, and evaluation processes are conducted and documented in line with ISO/IEC 17043.
Quality doesn’t happen by chance; it is measured, monitored, and improved. The Customized PT Assurance Model turns proficiency testing from a requirement into a natural part of your laboratory’s continuous improvement cycle. Contact us to design a PT program tailored to your laboratory.
PT Nexus – Connecting Laboratories. Advancing Quality.