Self test 5.2B – Validation of liquid chromatography mass spectrometry (LC-MS) methods

You are validating a LC/MS analysis of L-PFOS in ground water and for trueness evaluation, you are analyzing a commercial CRM sample.

CoA

You are using matrix matched calibration.

Your analysis data is:

Number of result	C (ng/L)
1	13.96
2	14.00
3	12.51

1. Calculate bias and give the answer with 2 decimals (unit: ng/L):

2. Calculate relative bias and give the answer with 1 decimal (unit: %):

3. For evalution of your bias, calculate zeta-score and please present it with three significant digits.

4. Result is:

Satisfactory

Questionable

Unsatisfactory

5. Possible reasons for unsatisfactory results (click all that apply):

CRM sample matrix has less matrix components than a matrix matched calibration solution.

CRM sample has more matrix components than you matrix matched calibration solution.

Your calibration solution has degraded.

You are running your analysis on a dirty instrument.

6. Method bias is:

Statistically significant

Not statistically significant

7. Could this CRM be used for evaluating L-PFOS method bias in the case of sea water?

Yes

No

8. Please indicate which of the main problems from the given list can be expected to occur when carrying out spiking in the following analytical situations. Please make a choice in the following table.

Analytical situation	Analyte is unstable	Difficult to disperse the analyte in the matrix	Analyte encompasses a number of different individual compounds
Determining meropenem antibiotic in blood plasma
Determination of amino acids in tea
Determination of residues of explosives in soil
Determining anthocyanins in bilberries
Determining ascorbic acid in apples