Professional reference · private review version

Practical tools

Laboratory quantities in context. Educational calculations, not conformity decisions, safety assessments or regulatory approval.

Measurement uncertainty

Compare the expanded interval x ± U with a user-supplied reference limit. Keep illustrative decision rules separate from real conformity assessment.

Convert mg/kg, µg/kg, ppm and ppb on an exact mass/mass basis. No density, dilution factor or unverified legal limit.

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