R****n
发帖数: 708 | 1 There is a ghost peak which always comes out at the same time.
Even I ran a blank in IPA / Water gradient or ACN / water gradient.
I also changed two different columns.
I changed solvent too.
The baseline around 900m/z elevated too. some time spectrum will show some
multiple changed peaks.
Can't figure out what is that.
Need your suggestion! Thank you! |
H********f
发帖数: 289 | 2 when you change solvents, did you change both aq and organic solvents at the
same time? If yes, also check the needle wash solvents--stuff from them
could also show up on LC/MS. |
f*********e
发帖数: 1144 | 3 ESI-TOF? or ESI-ion trap?
【在 R****n 的大作中提到】
: There is a ghost peak which always comes out at the same time.
: Even I ran a blank in IPA / Water gradient or ACN / water gradient.
: I also changed two different columns.
: I changed solvent too.
: The baseline around 900m/z elevated too. some time spectrum will show some
: multiple changed peaks.
: Can't figure out what is that.
: Need your suggestion! Thank you!
|
m****e
发帖数: 255 | 4 Looks like your are using Agilent's TOF. The 922.0099 mass may come from
your tuning mix. The hump on your TIC is normal for gradient. |
R****n
发帖数: 708 | 5 Yes, I did. The peak will show a little bit small. Should I keep washing a
couple times to remove it?
the
【在 H********f 的大作中提到】
: when you change solvents, did you change both aq and organic solvents at the
: same time? If yes, also check the needle wash solvents--stuff from them
: could also show up on LC/MS.
|
R****n
发帖数: 708 | 6 ESI QTOF
【在 f*********e 的大作中提到】
: ESI-TOF? or ESI-ion trap?
|
R****n
发帖数: 708 | 7 maybe hump is just because of the drastic gradient change?
【在 m****e 的大作中提到】
: Looks like your are using Agilent's TOF. The 922.0099 mass may come from
: your tuning mix. The hump on your TIC is normal for gradient.
|
H********f
发帖数: 289 | 8 Use high quality solvents for all the needle wash then. You also can try
changing to different wash cycles and use more intense wash. Which LC system
are you using?
【在 R****n 的大作中提到】
: Yes, I did. The peak will show a little bit small. Should I keep washing a
: couple times to remove it?
:
: the
|
R****n
发帖数: 708 | 9 LC system is Agilent 1200. How to wash needle? high organic wash by pass and
main pass?
Do you know anything about baseline noise around 900 m/z?
system
【在 H********f 的大作中提到】
: Use high quality solvents for all the needle wash then. You also can try
: changing to different wash cycles and use more intense wash. Which LC system
: are you using?
|
H********f
发帖数: 289 | 10 I never observed noise around m/z 900
which water you used? Recommend MilliQ water--it is better than HPLC grade
water for LC/MS |
