Uncertainty estimation in organic elemental analysis using information from proficiency tests.

Area of Science:

• Analytical Chemistry
• Environmental Chemistry
• Laboratory Science

Background:

• Organic elemental analysis (OEA) is crucial for characterizing organic matter.
• Accurate uncertainty estimation in OEA is vital for reliable laboratory results.
• Proficiency testing (PT) provides a framework for inter-laboratory comparisons and quality assessment.

Purpose of the Study:

• To evaluate the uncertainty associated with organic elemental analysis (C, H, N, S).
• To assess within-laboratory and between-laboratory variances in OEA.
• To compare individual laboratory performance against overall technique uncertainty.

Main Methods:

• Utilized data from six proficiency tests involving 35 Spanish laboratories.
• Estimated technique uncertainty using relative variances from pure substances and complex matrices (soil, milk, oil, ash, petroleum coke).
• Calculated individual laboratory uncertainties from historical PT data for pure substances.

Main Results:

• Individual laboratory uncertainties were found to be comparable to the overall technique uncertainty.
• A correlation was observed between individual laboratory uncertainties and combined z-scores.
• The study assessed the longitudinal performance evolution of participating laboratories.

Conclusions:

• Proficiency testing data effectively characterizes OEA uncertainty.
• Individual laboratory performance in OEA is quantifiable and comparable to established technique uncertainties.
• The findings support robust quality assurance in elemental analysis for diverse sample types.