Residual solvents external standard injections

[RhysB]

Morning all,

I'm currently developing a method for determining residual solvents in water soluble products. Its not HS as we don't have the money for one (QC have been asking for quite a while to get a unit). I've pretty much sorted out the method but I'm just wondering about the external standard injectiuons. Now normally I would do 3 at different concentrations to get the calibration curve and then do a triplicate of the sample. The QA chap who is assisting with the validation protocol has told me that I need to do duplicate shots of the standards. we are currently working to <0.5% solvents in the products, and theres only 1-2 samples in a day (so run very irregularly). We are working to EP 2.4.24 and 5.4.

This probably isn't enough information so If I've missed anything important I'm sure you will ask

[Johnny Rod]

It depends really on how tough your method is, I would have thought duplictae is a bit minimal to get reasopnable preciison. Are you using an internal standard? Also do you have a range of levels you're looking for? It would be easier to calibrate at the spec limit as a single point calibration through zero if you're mainly loking for a pass/fail vs spec rather than assigning an accurate quantity in each sample.