Estimation of measurement uncertainty in chemical analysis

Self-test 9.5

Here you can test your understanding of where to obtain data for estimating measurement uncertainty contributions of different uncertainty sources and how to obtain uncertainty estimates from these data.

1. In a liquid chromatographic method determination of tartrazine colorant a sample solution with code SK27 was injected five times during the same day. The injection order was random (i.e. the five samples of SK27 were randomly mixed with other sample solutions and calibration solutions).  Five chromatograms of SK27 were obtained. The areas of tartrazine peaks on the chromatograms were 1255, 1248, 1262, 1251 and 1257 mAU·s. Different useful information for measurement uncertainty estimation can be extracted from these data. Which of the following statements are true?

2. An analyst is using a titration procedure of determination of the net content of basic substances in a biological sample. He carried out sample preparation (several extraction steps), obtained 100 ml of a solution and made 5 replicate titrations of 10 ml aliquots (measured by a volumetric pipette) of this solution with HCl solution. He obtained five values and calculated standard deviation of these values. This standard deviation can be used in measurement uncertainty calculation. Which of the following statements are correct?


 

Accept Cookies