Chromatography Forum

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

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.