LOQ FOR IMPURITY

[pliva]

FIRST OF LLWISH YOU ALL A VERY HAPPY VALENTINEDAY ,
The limit for my inpurity for a formulated product is 0.5%. so how to find out the theoretical LOQ and actual LOQ by means of linearity curve methodaccording tot ich guideline.

[tom jupille]

I'm not quite sure about the distinction between "actual" and "theoretical" LOQ. In any case, I believe ICH suggest 10X noise for LLOQ.

[pve]

Hi Pliva
according to ICH, LOD : 3 x noise and LOQ : 10 x noise
regards

[gbalock]

Pliva,
I would suggest you do a standard curve from about 0.05% to about 2%. I would do five levels and three replicates. Perform a linear regression and determine the slope and standard deviation of the residuals. Use the formula 10 times the SDR divided by the slope to determine the estimated LOQ. Prepare a solution of analyte at the estimated LOQ and inject it 10 times. Determine the RSD of the response and if the RSD is less than 10%, that level can be used as your LOQ.
George

[pliva]

Pliva,
I would suggest you do a standard curve from about 0.05% to about 2%. I would do five levels and three replicates. Perform a linear regression and determine the slope and standard deviation of the residuals. Use the formula 10 times the SDR divided by the slope to determine the estimated LOQ. Prepare a solution of analyte at the estimated LOQ and inject it 10 times. Determine the RSD of the response and if the RSD is less than 10%, that level can be used as your LOQ.
George

thank you all for your valuable sugestion.