Re: PPG peaks

[RCody]

Please tell the group what kind of mass spectrometer you are using.
The mass analyzer can have a big influence on what is observed. This
subject was discussed for MALDI analysis of polystyrenes in an
interlaboratory study. The reference is:

Guttman, C.M., et al., NIST-Sponsored Interlaboratory Comparison of
Polystyrene Molecular Mass Distribution Obtained by Matrix-Assisted
Laser Desorption/Ionization Time-of-Flight Mass Spectrometry:
Statistical Analysis. Analytical Chemistry, 2001. 73(6): p. 1252-1262.

A question to the polymer mass spectrometrists in the group: Could a
skewing toward higher mass in ESI reflect greater hydrophobicity (and
therefore greater ESI response) for the larger oligomers?

On Jul 25, 11:12�am, Andy <slj20080...@gmail.com> wrote:
} Hi�^�
}
} My friend and I have some questions about PPG peaks at ESI mode:
}
} �- PPG1000 the center of the +1 ions envelope is around mass 1000 (I
} don�^�^�t care which peak, but is not far from mass 1000)
}
} - PPG2000 the center of the +1 ions envelope is around mass 2000.
}
} - PPG2700 center of the +1 ions envelope is around mass 3200. Why is
} not around mass 2700? The spread of the envelope is from mass2400 to
} 4000
}
} - PPG3500 center of the +1 ions envelope is around mass 4700. Why is
} not around mass 3500? The spread of the envelope is from mass3500 to
} 6000
}
} �Without running the PPG1000, I can predict the +1 ions is around
} 1000, but for PPG3500 and PPG with higher value, I cannot predict the
} +1 ions envelope. Is there any method or calculation to do this
} prediction.
}
} Thank you for your time.
}
} SLJ