By psv on Saturday, June 12, 2004 - 01:59 am:
While method development for unknown
impurities by HPLC - UV detector, how
wavelength is finalised.
Should the wavelength be the one at which
area count for main peak is largest, (this is
especialy important when impurities at other
wavelngths show signinficant rise in area and
go beyond 0.1% while main peak area is
small)
By Anonymous on Monday, June 14, 2004 - 12:49 pm:
Since impurities standards or their potencies are often unavailable, we do impurities by area normalization and measure them at the same wavelength as the API (which is its UV max).
By Basil on Tuesday, June 15, 2004 - 01:57 am:
I disagree with anonymous. You always should know at least one potential impuritie (previous chemical compound) and then I chose UV wavelength to obtain the same response for both compounds at the same concentration level.
Try always to work with the same (or between 0,8 to 1,2) relative response factor to main peak.