Paul Willetts is an analytical chemistry researcher associated with studies of laboratory performance and analytical sampling. The recovery-information report lists him at the MAFF Food Science Laboratory in Norwich, establishing the identity independently of unrelated authors with the same name.[ref]
Harmonised guidelines for the use of recovery information in analytical measurement by Michael Thompson and others. Eurachem-hosted text, title page and affiliation 4.
With Michael Thompson, Sharron Anderson, Paul Brereton and Roger Wood, Paul Willetts studied collaborative sampling of wheat and green coffee from bulk lots. Multiple samplers allowed the study to distinguish variation under different sampling conditions. Between-sampler variation contributed significantly for two wheat analytes; the coffee results showed significant sampling-repeatability variation without a detected significant sampling-reproducibility contribution.[ref]
Collaborative trials of the sampling of two foodstuffs, wheat and green coffee by Michael Thompson and others. Abstract, sampling design and contrasting results.
The measurement begins before material reaches the instrument. For an original illustration, two perfectly repeatable preparations might contain and because the collected portions differ. Repeating each instrument reading a hundred times would not make those portions identical. Measurement repeatability within a portion and measurement reproducibility across the relevant procedures therefore cannot be inferred from the same replication design.
Paul Willetts also coauthored the recovery-information guidance. Together these contributions emphasize that sample matrix, material selection, preparation loss and stated measurement uncertainty belong in the interpretation of an analytical result. They cannot all be assessed by repeatedly reading a single prepared solution.
Articles by others on the same topic
There are currently no matching articles.