Quantification of uncertainty in mercury wastewater analysis at different concentration levels and using information from proficiency test with a limited number of participants

► A PT scheme for limited number of analytical laboratories was developed, conducted and assessed in a restrictive scenario. ► Measurement uncertainty was calculated for a non simple method in complex matrix samples without highest references of traceability. ► The worst case-scenario (with two different levels of analyte concentration) presented in this paper is not included in international guidelines for the assessment of measurement uncertainty. ► The procedure designed could be applied to many other common and similar scenarios. ► The study provided useful information for analytical quality assessments, official controls and environmental managements.