ESTIMATING MEASUREMENT UNCERTAINTY USING A CAUSE AND EFFECT AND RECONCILIATION APPROACH PART 2 - MEASUREMENT UNCERTAINTY ESTIMATES COMPAREDWITH COLLABORATIVE TRIAL EXPECTATION

Measurement uncertainty estimates are presented for ten analytical met hods, covering over 45 combinations of analyte, matrix and concentrati on. The uncertainty estimates were produced using a cause and effect a pproach published previously. Techniques include gas and liquid chroma tography, elemental analysis by graphite furnace atomic absorption spe ctrometry, inductively coupled plasma-mass spectrometry, inductively c oupled plasma-optical emission spectrometry, and titrimetry. A range o f different types of data is used, including quality control data and method validation studies. The major contributions to the uncertainty for each method and a brief description of their evaluation are given. In most cases, a combination of an experimental estimate of overall p recision and the uncertainty associated with overall bias, measured as recovery, across representative sample types and analyte concentratio ns contributes the majority of the uncertainty, although in several ca ses it was essential to consider additional factors. The uncertainty e stimates are also compared with collaborative trial results where avai lable, and with reproducibility estimates obtained from the Horwitz fu nction.