Spike Sample of RS for 2 analyte for as such sample.

[mehtapratik2]

Hello sir,
Currently I am working on a injectable product having 1 API label claim 0.2 mg/mL and other API has label claim 9mg/mL. in RS analysis both have same wavelength..and due to low label claim sample injeted as such(as per monograph assay method)....I have prepared Spiked sample in placebo sample during method development....
I have 2 label claim for unknown of both,so both placebo injection is required to confirm unknown for specific analyte.
If I Spike i impurity in sample then my sample concentration will change due to as such sample injection in method.
I want to know that, is there any other method to prepare Spike sample for method precision?
Thanks & Regards
Pratik

[Consumer Products Guy]

Pipet 9.00 ml sample (yes, there are 9.00ml class A volumetric pipets) into a 10ml class A volumetric flask. Add spike of active(s). Mix and dilute to 10.00ml with your solvent.

And I'd do similar with placebo.

[mehtapratik2]

Thank you for your reply.
But when diluting 9ml Sample to 10 ml with diluent.my sample concentration will change for API 0.2 mg/mL to 0.18 mg/mL and for other analyte 9mg/mL to 8.1 mg/mL... wheres I am using as such sample for injection....then may I have to change label claim for this type of calculation?..
I have to Spiked 3 impurities for 2 analyte in as such samples.then may I proceed through mix impurity stock solution?

[Consumer Products Guy]

Me? I'd include the dilution and make an automatic correction in the automated calculations. Like a 10/9 factor.