identifying secondary peaks

[jackie1016]

hi carls,

yes the peak areas of carbimazole for both runs are reproducible..

the peak area of the carbimazole in gradient run is different from the peak area in isocratic run using the 20% acn (MPB)..

carbimazole peak area in gradient is : 139039.360
the unknown has an area of : 89739.365

when i run the carbimazole in isocratic using the 20% acn which is my MPB

my carbimazole peak has an area of :264495.584

if i combine the area of the carbimazole and the unknown i got : 228778.725

it a little bit close to the peak area of carbimazole in isocratic..

ill be testing a new batch of API soon for confirmation,.

thanks!

[carls]

[quote="jackie1016"]hi carls,

yes the peak areas of carbimazole for both runs are reproducible..

the peak area of the carbimazole in gradient run is different from the peak area in isocratic run using the 20% acn (MPB)..

carbimazole peak area in gradient is : 139039.360
the unknown has an area of : 89739.365

when i run the carbimazole in isocratic using the 20% acn which is my MPB

my carbimazole peak has an area of :264495.584

if i combine the area of the carbimazole and the unknown i got : 228778.725

it a little bit close to the peak area of carbimazole in isocratic..

quote]
So it looks like the peaks co-elute in gradient while they are separated in isocratic. I'd test your new API in the same way to ensure you haven't found a new impurity