{"id":746,"date":"2024-07-01T14:19:28","date_gmt":"2024-07-01T11:19:28","guid":{"rendered":"https:\/\/sisu.ut.ee\/measurement\/?page_id=746"},"modified":"2024-07-01T14:19:28","modified_gmt":"2024-07-01T11:19:28","slug":"self-test-9-7","status":"publish","type":"page","link":"https:\/\/sisu.ut.ee\/measurement\/self-test-9-7\/","title":{"rendered":"Self test 9.7"},"content":{"rendered":"
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<\/p>\n\n

Here you can test your understanding of where to obtain data for\u00a0estimating measurement uncertainty contributions of different\u00a0uncertainty sources and how to obtain uncertainty estimates from these data, as well as how to combine the standard uncertainty estimates.<\/p>\n<\/div>\n\n

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An analyst started to implement an analysis for determining phosphorous content in a gaseous drink with UV-Vis spectrophotometric method. For this, he had to perform a 200 times dilution from the sample. The analyst thought about 3 different ways, how to perform the dilution (diluent is water-based mixture containing the photometric reagents):<\/p>\n

-1- Pipetting 0.5 ml of sample into a 100 mL volumetric flask and adding the diluent to the mark<\/strong><\/p>\n

An automatic pipette with variable range (see the table) can be used.<\/p>\n\n\n\n\n\n\n\n\n
\n

Model<\/b><\/span><\/p>\n<\/td>\n

\n

Volume range (<\/b>\u03bc<\/b>l)
\nColor code<\/b><\/span><\/p>\n<\/td>\n

\n

Testing volume<\/b><\/span><\/p>\n<\/td>\n

\n

Error limits by the manufacturer<\/b><\/span><\/p>\n<\/td>\n<\/tr>\n

\n

Systematic error<\/b><\/span><\/p>\n<\/td>\n

\n

Random error<\/b><\/span><\/p>\n<\/td>\n<\/tr>\n

\n

\u00b1%<\/b><\/span><\/p>\n<\/td>\n

\n

\u00b1\u03bcl<\/b><\/span><\/p>\n<\/td>\n

\n

\u00b1%<\/b><\/span><\/p>\n<\/td>\n

\n

\u00b1\u03bcl<\/b><\/span><\/p>\n<\/td>\n<\/tr>\n

\n

100 \u2013 1000 \u03bcl Increment:
\n1 \u03bcl<\/span><\/p>\n<\/td>\n

\n

100 \u2013 1000 Blue<\/span><\/p>\n<\/td>\n

\n

100 \u03bcl<\/span><\/p>\n<\/td>\n

\n

3.0<\/span><\/p>\n<\/td>\n

\n

3.0<\/span><\/p>\n<\/td>\n

\n

0.6<\/span><\/p>\n<\/td>\n

\n

0.6<\/span><\/p>\n<\/td>\n<\/tr>\n

\n

500 \u03bcl<\/span><\/p>\n<\/td>\n

\n

1.0<\/span><\/p>\n<\/td>\n

\n

5.0<\/span><\/p>\n<\/td>\n

\n

0.2<\/span><\/p>\n<\/td>\n

\n

1.0<\/span><\/p>\n<\/td>\n<\/tr>\n

\n

1000 \u03bcl<\/span><\/p>\n<\/td>\n

\n

0.6<\/span><\/p>\n<\/td>\n

\n

6.0<\/span><\/p>\n<\/td>\n

\n

0.2<\/span><\/p>\n<\/td>\n

\n

2.0<\/span><\/p>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

\u00a0<\/p>\n

\"100ml<\/p>\n

Flask filling uncertainty can be estimated as \u00b1 1 drop (\u00b10.03 ml) and temperature is not different from calibration temperature more than 4 \u00b0C.<\/p>\n

-2- Pipetting 5 ml of sample into a 1000 mL volumetric flask and adding the diluent to the mark<\/strong><\/p>\n

Glassware shown here can be used:<\/p>\n

\"5ml
\nPipetting repeatability with 5 ml glass pipette in this lab was estimated previously from repeated measurements and estimated as 0.011 ml.
\n\"1L
\nFlask filling uncertainty can be estimated as \u00b1 2 drops (\u00b10.06 ml) and temperature is not different from calibration temperature more than 4 \u00b0C.<\/p>\n

-3- Pipetting 50 \u03bcl of sample and 9.95 ml of diluent<\/strong><\/p>\n

Two automatic pipettes (see information in the table) can be used.<\/p>\n\n\n\n\n\n\n\n\n\n\n\n
\n

Model<\/b><\/span><\/p>\n<\/td>\n

\n

Volume range
\nColor code<\/b><\/span><\/p>\n<\/td>\n

\n

Testing volume<\/b><\/span><\/p>\n<\/td>\n

\n

Error limits by the manufacturer<\/b><\/span><\/p>\n<\/td>\n<\/tr>\n

\n

Systematic error<\/b><\/span><\/p>\n<\/td>\n

\n

Random error<\/b><\/span><\/p>\n<\/td>\n<\/tr>\n

\n

\u00b1%<\/b><\/span><\/p>\n<\/td>\n

\n

\u00b1\u03bcl<\/b><\/span><\/p>\n<\/td>\n

\n

\u00b1%<\/b><\/span><\/p>\n<\/td>\n

\n

\u00b1\u03bcl<\/b><\/span><\/p>\n<\/td>\n<\/tr>\n

\n

10 \u2013 100 \u03bcl Increment: 0.1 \u03bcl<\/span><\/p>\n<\/td>\n

\n

10 \u2013 100 \u03bcl Yellow<\/span><\/p>\n<\/td>\n

\n

10 \u03bcl<\/span><\/p>\n<\/td>\n

\n

3.0<\/span><\/p>\n<\/td>\n

\n

0.3<\/span><\/p>\n<\/td>\n

\n

1.0<\/span><\/p>\n<\/td>\n

\n

0.1<\/span><\/p>\n<\/td>\n<\/tr>\n

\n

50 \u03bcl<\/span><\/p>\n<\/td>\n

\n

1.0<\/span><\/p>\n<\/td>\n

\n

0.5<\/span><\/p>\n<\/td>\n

\n

0.3<\/span><\/p>\n<\/td>\n

\n

0.15<\/span><\/p>\n<\/td>\n<\/tr>\n

\n

100 \u03bcl<\/span><\/p>\n<\/td>\n

\n

0.8<\/span><\/p>\n<\/td>\n

\n

0.8<\/span><\/p>\n<\/td>\n

\n

0.2<\/span><\/p>\n<\/td>\n

\n

0.2<\/span><\/p>\n<\/td>\n<\/tr>\n

\n

1 \u2013 10 ml Increment: 0.01 ml <\/span><\/p>\n<\/td>\n

\n

1 \u2013 10 ml Turquoise<\/span><\/p>\n<\/td>\n

\n

1.0 ml<\/span><\/p>\n<\/td>\n

\n

3.0<\/span><\/p>\n<\/td>\n

\n

30<\/span><\/p>\n<\/td>\n

\n

0.6<\/span><\/p>\n<\/td>\n

\n

6<\/span><\/p>\n<\/td>\n<\/tr>\n

\n

5.0 ml<\/span><\/p>\n<\/td>\n

\n

0.8<\/span><\/p>\n<\/td>\n

\n

40<\/span><\/p>\n<\/td>\n

\n

0.2<\/span><\/p>\n<\/td>\n

\n

10<\/span><\/p>\n<\/td>\n<\/tr>\n

\n

10 ml<\/span><\/p>\n<\/td>\n

\n

0.6<\/span><\/p>\n<\/td>\n

\n

60<\/span><\/p>\n<\/td>\n

\n

0.15<\/span><\/p>\n<\/td>\n

\n

15<\/span><\/p>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

Temperature did not differ from calibration temperature more than 4 \u00b0C.<\/p>\n

Please help analyst to decide, which of the abovementioned procedures has the smallest uncertainty estimate. For this, please calculate the uncertainty estimate of dilution factor (DF) for each of the procedure and present the results in the table below. Please use dots instead of comma for decimals separator and keep in mind the rule of reasonable significant digits (see section 4.5<\/a>).<\/p>\n\n\n\n\n\n\n\n
\n

\n<\/p><\/th>\n

\n

Absolute u<\/i>c<\/sub> of dilution factor (ml\/ml)<\/span><\/span><\/p>\n<\/th>\n

\n

Relative u<\/i>c<\/sub> of dilution factor (%)<\/span><\/p>\n<\/th>\n<\/tr>\n<\/thead>\n

\n

-1-<\/b> 0.5 ml \u2192 100 ml flask<\/span><\/p>\n<\/td>\n

\n

<\/span><\/span><\/span><\/span><\/p>\n<\/td>\n

\n

<\/span><\/span><\/span><\/span><\/p>\n<\/td>\n<\/tr>\n

\n

-2-<\/b> 5 ml \u2192 1000 ml flask<\/span><\/p>\n<\/td>\n

\n

<\/span><\/span><\/span><\/span><\/p>\n<\/td>\n

\n

<\/span><\/span><\/span><\/span><\/p>\n<\/td>\n<\/tr>\n

\n

-3-<\/b> 50 \u03bcl + 9.95 ml into a vial<\/span><\/p>\n<\/td>\n

\n

<\/span><\/span><\/span><\/span><\/p>\n<\/td>\n

\n

<\/span><\/span><\/span><\/span><\/p>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

According to the table with results, which of the procedure has the smallest uncertainty estimate?
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