Selection of test conc in RS

[sharma]

Dear All,

I would like to know how the test and standard concentration is selected in case of related substances test?

Regards

[aceto_81]

We use the minimal concentration where we still get the required LOQ.

Ace

[sharma]

My query is sometime we use 500 ppm solution or sometime less or more than this. So how we arrive at this concentration?

[prepcolumn]

My query is sometime we use 500 ppm solution or sometime less or more than this. So how we arrive at this concentration?

500 ppm means %0.05 and it is generally the reporting threshold, disregard limit for drug substances..