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LOQ FOR IMPURITY
Posted: Tue Feb 14, 2006 4:59 am
by 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.
Posted: Tue Feb 14, 2006 4:58 pm
by 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.
Re: LOQ FOR IMPURITY
Posted: Tue Feb 14, 2006 6:38 pm
by pve
Hi Pliva
according to ICH, LOD : 3 x noise and LOQ : 10 x noise
regards
LOQ
Posted: Thu Feb 16, 2006 9:00 pm
by 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
Re: LOQ
Posted: Tue Feb 21, 2006 8:33 am
by 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.