Who it is for
- ISO/IEC 17025 accredited laboratories
- Laboratories seeking accreditation
- Asbestos, glass fibres and soil testing laboratories
- Laboratories using SEM / EDX
Proficiency testing
Proficiency testing for asbestos, glass fibres and soils
Organisation of proficiency testing schemes for laboratories accredited to ISO/IEC 17025 or seeking accreditation.
Current programme
Reliability, competence and comparability of results
Microanalitica organises proficiency testing schemes (PT / ILC) for laboratories working in asbestos, man-made glass fibres and soils, in conformity with ISO/IEC 17043.
A structured proficiency testing service
Microanalitica organises and coordinates proficiency testing schemes (PT / ILC) in accordance with ISO/IEC 17043, with a strong focus on data quality, result comparability and interpretative support for participating laboratories.
When to participate
- Audit, surveillance or reaccreditation
- Verification of technical competence
- Monitoring data reliability
An additional test after a PT round or a Check Sample Test
After participating in a PT round or a Check Sample Test, the laboratory can receive 30% off the rate listed in the Check Sample Test information sheet for one new Check Sample Test registration for the same scheme and operating site, within 30 days of publication of the corresponding report. It can be useful to check performance again, for example after a score exceeding 2 in absolute value (|z|, |z′| or |zₚ| > 2). This option is available regardless of the outcome of the previous test. The registration form automatically checks eligibility and displays the applicable rate.
Upcoming deadlines
Registration deadlines for upcoming proficiency testing schemes.
Glass fibres — Alkali and alkaline-earth oxides
MMMF_01
Asbestos dispersed in water
WATER_01
Proficiency testing programme
Choose a proficiency testing scheme by material and measurement. Each scheme page provides the test item, instructions, assessment criteria, dates and online registration.
ISO/IEC 17043 conformity
Microanalitica srl organises proficiency testing schemes in conformity with ISO/IEC 17043:2023.
Asbestos proficiency testing PT Asbestos
Compare asbestos analysis results in soil, water and airborne-fibre test items using SEM/EDX. Select the scheme matching your laboratory activities.
Frequency: annual · generally scheduled in the same period each year.
Glass fibre proficiency testing PT Glass fibres
Proficiency testing for analytical competence on man-made glass fibres (dimensional and/or compositional measurements).
Frequency: annual · generally scheduled in the same period each year.
Soil sieving proficiency testing PT Soils
PT scheme on soil matrices to assess comparability of granulometric determinations.
Frequency: annual · generally scheduled in the same period each year.
| Sample | Proficiency test | Registration deadline | Scheme code | Scheme details | ||
|---|---|---|---|---|---|---|
| Soil | Coarse fraction (2 mm sieving) | 26/02/2027 | SETA_01 round 6 | Go | ||
How to read the PT evaluation
These indicators help interpret the laboratory result and the reliability of the comparison.
zₚ score: asymmetric limits
zₚ is the score adopted by Microanalitica for assessments with asymmetric limits, meaning different distances above and below the assigned value. It uses Poisson-type limits at 95% and 99.73%, widened to account for overdispersion. It is distinct from z′.
zₚ is zero at the assigned value, negative for lower results and positive for higher results.
|zₚ| ≤ 2: satisfactory; 2 < |zₚ| < 3: questionable (warning); |zₚ| ≥ 3: unsatisfactory (action).
How zₚ is calculated
To recalculate zₚ, use your result, the assigned value and the limits stated in the report. Small differences may arise from rounding of the published values.
L₂ and U₂ are the warning limits (−2 and +2); L₃ and U₃ are the action limits (−3 and +3). The score varies linearly between these reference points and continues beyond ±3.
xᵢ < L₂: zₚ = −2 − (L₂ − xᵢ)/(L₂ − L₃)
L₂ ≤ xᵢ < xₚₜ: zₚ = 2(xᵢ − xₚₜ)/(xₚₜ − L₂)
xₚₜ ≤ xᵢ ≤ U₂: zₚ = 2(xᵢ − xₚₜ)/(U₂ − xₚₜ)
xᵢ > U₂: zₚ = 2 + (xᵢ − U₂)/(U₃ − U₂)
L₂ ≤ xᵢ < xₚₜ: zₚ = 2(xᵢ − xₚₜ)/(xₚₜ − L₂)
xₚₜ ≤ xᵢ ≤ U₂: zₚ = 2(xᵢ − xₚₜ)/(U₂ − xₚₜ)
xᵢ > U₂: zₚ = 2 + (xᵢ − U₂)/(U₃ − U₂)
Microanalitica adopts the overdispersion factors f₂ = 0.2·xₚₜ^0.14 and f₃ = 0.2·xₚₜ^0.19, with xₚₜ expressed in fibres/mm². The Poisson-type limits are widened by subtracting xₚₜ·f from the lower limit and adding it to the upper limit.
Assigned value xₚₜ
This is the value against which participant results are compared. Microanalitica derives it from the set of results using a robust mean, which limits the influence of extreme values. It is the statistical reference for that specific round.
z score
z = (xi − xpt) / σpt
It shows how far the laboratory result is from the assigned value, in units of the standard deviation for proficiency assessment. Generally: |z| ≤ 2 satisfactory; 2 < |z| < 3 warning signal; |z| ≥ 3 unsatisfactory and requiring action.
z′ score and uncertainty u(xₚₜ)
z′ = (xi − xpt) / √(σpt2 + u2(xpt))
The uncertainty u(xₚₜ) expresses the precision of the assigned-value estimate. It helps assess its reliability and avoids penalising a laboratory because of uncertainty in the statistical reference. When this uncertainty is not negligible compared with σₚₜ, z′ may be used because it includes that uncertainty in the calculation.
PT item and quality control
A PT item must not be regarded as a certified reference material: its assigned value is intended for evaluation within the PT round and does not, by itself, constitute metrological certification. It does not have a certificate, a statement of metrological traceability or qualification for a specific reference use. If enough material remains, it is stored correctly and is stable for the intended period, it may nevertheless be used for internal quality control, for example in control charts, repeatability or trend checks and training, using internally defined criteria.
xᵢ = participant result; xₚₜ = assigned value; σₚₜ = standard deviation for proficiency assessment; u(xₚₜ) = standard uncertainty of the assigned value.
In a hurry or missed the deadline?
If you missed the enrolment deadline for proficiency testing or you need results quickly, you can use our Check Sample Test service, with sample submission and a rapid report.
Sample shipment: free of charge.
* The indicated dates may be shifted by ± 5 days.
Prices are given excluding VAT.
* DMGPL-2ES: Geometric mean diameter weighted by length (−2 standard errors).