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Table 9 Uncertainty due to balance for weighing the sample [W TSPM ] and [W ANA ]

From: Quantifying uncertainty in the measurement of arsenic in suspended particulate matter by Atomic Absorption Spectrometry with hydride generator

Sample I.D. Total weight of SPM deposited on 18 cm × 23 cm filter paper (gm) [W TSPM ] (x) Weight of SPM deposited on 18 cm × 11.5 cm filter paper area taken for analysis (gm)[W ANA ] (x1) Uncertainty in weighing balance (g) u(x) Standard uncertainty in total weight deposit on filter paper u(x)/x Standard uncertainty in weight taken for analysis u(x)/x1
S-1 0.2210 0.1105 0.00047 0.0021 0.0042
S-2 0.1136 0.0568 0.00047 0.0041 0.0081
S-3 1.3088 0.6544 0.00047 0.0004 0.0007
S-4 0.1406 0.0703 0.00047 0.0033 0.0065
S-5 0.1896 0.0948 0.00047 0.0025 0.0049
S-6 0.2404 0.1202 0.00047 0.0019 0.0038
S-7 0.7760 0.3880 0.00047 0.0006 0.0012
  1. Details of the balance:
  2. 1. Make & model = Mettler Tolledo AX 105
  3. 2. Maximum capacity = 110 g
  4. 3. Uncertainty reported in literature = ± 0.1 mg at 25 ± 2°C
  5. 4. Linearity (mg)/readability (mg)/repeatability (mg) = ± 0.2/0.01/0.07
  6. Uncertainty due to linearity/readability/repeatability = = 0.212 mg The contribution needs to be counted twice, once for tare, and the other for gross weight, as each is an independent observation and linearity effects are not correlated. So the standard uncertainty for the measurement of mass is given by: 2 × 0.212 = 0.424 mg or 0.424 × 10-3 g