AOAC Guidance on FA Immunoassay Validation (August 2023)

= ( 0 )

�� % 100 � � − �

1663

1664 1665 1666 1667 1668 1669 1670 1671 1672 1673 1674 1675 1676 1677 1678 1679 1680 1681 1682 1683 1684

2.2.6. Prepare an operator characteristic (OC) curve for LOQ

2.2.6.1.

Use a normal distribution calculation function to calculate the probability of obtaining a result higher than the LOQ for the given concentration using the

calculated S i and assuming a normal distribution.

2.2.6.2.

Normal distribution curves can be estimated in Excel with the following function, where LOQ is set at the estimate calculated above, S i is calculated

according to the linear regression

= 1 – NORMDIST(LOQ, mean concentration, S i , 1)

2.2.6.3.

Plot the probabilities versus concentration to prepare the OC curve.

2.2.7. Calculations/procedures for multiple matrices

Model %RSD i across a range of concentrations (as described above) for all matrices together. It is generally expected that the relationship between %RSD i and concentration will be sufficiently similar across matrices to conduct a single analysis

2.2.7.1.

for the combined data from all matrices.

2.2.7.2.

If the relationship between standard deviation and concentration appears to be substantially different between matrices, consult with the AOAC Statistics

Committee and Expert Review Panel.

2.2.8. Example Data and Calculations

Table 2: Example Data

Slope

0.0755 0.1368

Si(0)

1685

Example Data

0 20 40 60 80 100

RSD(%)

0

1

2

3

4

RSD

RSD(Q)

1686 1687