Chromatography Forum

Good afternoon:

Anyone of you know how to analyse p-nitrophenol sodium in pesticide by HPLC method?

Previously i was using Column C18, together with mobile phase (water 60%:methanol 40%,adjusted to pH 3.0 by phosphoric acid). But, the method seem like unstable and i cant even get a "sharp" peak. Somemore, i also cant find a suitable internal standard because most of the IS cant dissolve in water.

Thanks.

Mobile Phase: acetonitrile / water = 40 / 60
Flow rate: 1ml/min
Temperature: 40C
Detection: 1) UV/VIS : 280nm
Injection vol: 5ul
Sample load: p-nitrophenol : 0.1 g/L
m-nitrophenol : 0.1 g/L
o-nitrophenol : 0.1 g/L
Equipment: 1) Agilent 1120 Compact LC
Note: 1: p-nitrophenol
2: m-nitrophenol
3: o-nitrophenol
That gives sharp peaks with a standard C18 column 4,6mmID x 150mmL 5µm. Buffer capacity of your Phosphoric acid is not good and difficult to get an equilibrium. Good luck.

Thanks Mr Gerhard Kratz.