I hope this reach you well. Actually I’m developing a oil and as method in ELSD and DAD.
Is a normal phase method, DNAP column and heptane mobile phase, in order to separate mono, di, tri, tetra and penta ring of aromatics; and saturates.
Di, tri, tetra and penta aromatics look very good in DAD; but I couldn’t see saturates and mono aromatics in ELSD.
I’ve used different parameters:
- Temperatures: 30, 35, 40, 50 °C.
- Gain: 1, 3, 5, 7, 10, 12.
- Noise filter: 0.5, 5, 10 s.
- Injected a 100% gasoline and toluene and just see a little peak 100 mV.
I tried this:
- Background Noise (Stray Light) Test. Get a mv signal of 250 mV for heptane, looks line good according the service manual. For gain 12, 150 mV for water and 200mv for normal phase.
- We cleaned the nebulizer as manual said.
What do you recommend to do in order to increase the sensitivity? Or test what’s going on…
Thanks in advanced.