unexpected area increase in hplc

[ramvaka]

What is the reason for unexpected area increase in hplc? Earlier was like 400000 and now increased to 700000 without any chanse in composition of mobile phase and column

[DSP007]

What is the reason for unexpected area increase in hplc? Earlier was like 400000 and now increased to 700000 without any chanse in composition of mobile phase and column

Not reason:
400000 units - its peak without liner scale of chromatograph . Light T% more 99 (D>2) in DAD , electonic signal is a biggest unit on analog-digital convenctor and other.

Who says the size of mountains, without seeing her top?
Also - in chromatography we see not absolute number of phisical parametrs , but the relationship these parameters portions between separated substances. Recalbrate system from standart solution and work...

[tom jupille]

What DSP007 is trying to say (I think) is that area counts are arbitrary (actually, the units would be something like mV-sec). That said, the first question I would ask is "are your retention times still the same? Next question: when you said "without any change in composition of mobile phase . . .", were you using the exact same batch of mobile phase and if so, how old was it? Sometimes seemingly insignificant changes (or aging) can change absorbance spectra significantly. That's why calibration should be done daily.

[ramvaka]

I tried with same batch mobile phase and different lot mobile phase , everything gives same double area. second thing RT is same like previous , no change. Other thing, unit for area millivolts.

[tom jupille]

Autosampler settings? "Pilot error" preparing standards?

Other thing, unit for area millivolts.

Can't be. Peak *height* would be in millivolts. Area units would have to be the product of Y-axis units (millivolts) and X-axis units (usually time).