MOOC: Validation of liquid chromatography mass spectrometry (LC-MS) methods (analytical chemistry) course

Self test 6.1

1.

Is it recommended to order a CRM to determine the precision of a method?

2.

An analyst intended to determine the repeatability of the method. He analyzed a food sample with LC-MS. He carefully homogenized the sample in a blender and took a subsample. With the subsample he carried out sample preparation (consisting of extraction, precipitation and centrifugation). As a result he obtained a clear solution. He transferred it into a 100 ml volumetric flask and filled it up to the mark with the mobile phase. He analyzed 10 aliquots of this solution during the same day and calculated the repeatability as standard deviation of the results.

 Question: What did he actually determine?

3.

Should the precision be evaluated before the truness?