Chromatography Forum

To whom it concerns,
I have two questions and should be considered independent of each other.

1. In the BP it states that minor adjustments can be made to a liquid chromatography method...example :column length +/- 70%, particle size: maximal reduction of 50%, no increase permitted. What happens if i go out side these limits? for example on one parameter? Does the method therefore become no longer a BP method and therefore would be considered a new method? requiring full validation?.

2.If a method states the use of potassium dihydrogen phosphate for buffer/Mobile phase make up. Can you change buffer salt to another?...and if so, is this then considered an entirely new method and no longer represents the BP method?

Regards
Seamus Moroney

1. I can't talk from direct experience with BP methods, but for USP, so long as you are within the de facto adjustment limits and you meet system suitability, the method is considered valid. Go outside those limits and and you have modified the method; the modified method must be revalidated.

2. Again, I would assume that BP follows similar rules to USP. Changing the buffer salt is clearly a modification of the method and does require revalidation.