title: Transient signal isotope analysis: validation of the method for isotope signal synchronization with the determination of amplifier first-order time constants.
abstract: BACKGROUND
  During transient signal acquisition by Multi-Collection Inductively Coupled Plasma Mass Spectrometry (MC-ICPMS), an isotope ratio increase or decrease (isotopic drift hereafter) is often observed which is related to the different time responses of the amplifiers involved in multi-collection. This isotopic drift affects the quality of the isotopic data and, in a recent study, a method of internal amplifier signal synchronization for isotope drift correction was proposed. In this work the determination of the amplifier time constants was investigated in order to validate the method of internal amplifier signal synchronization for isotope ratio drift correction.
  
  
  METHODS
  Two different MC-ICPMS instruments, the Neptune and the Neptune Plus, were used, and both the lead transient signals and the signal decay curves of the amplifiers were investigated.
  
  
  RESULTS
  Our results show that the first part of the amplifier signal decay curve is characterized by a pure exponential decay. This part of the signal decay was used for the effective calculation of the amplifier first-order time constants. The small differences between these time constants were compared with time lag values obtained from the method of isotope signal synchronization and were found to be in good agreement.
  
  
  CONCLUSIONS
  This work proposes a way of determining amplifier first-order time constants. We show that isotopic drift is directly related to the amplifier first-order time constants and the method of internal amplifier signal synchronization for isotope ratio drift correction is validated.
authors.affiliation: Institut de Physique du Globe de Paris, Sorbonne Paris Cité, Université Paris-Diderot, UMR CNRS 7154, 1 rue Jussieu, 75238, Paris, Cedex, France.
authors.forename: Alkiviadis
authors.initials: A
authors.lastname: Gourgiotis
authors.affiliation: Institut de Physique du Globe de Paris, Sorbonne Paris Cité, Université Paris-Diderot, UMR CNRS 7154, 1 rue Jussieu, 75238, Paris, Cedex, France.
authors.forename: Gérard
authors.initials: G
authors.lastname: Manhès
authors.affiliation: Institut de Physique du Globe de Paris, Sorbonne Paris Cité, Université Paris-Diderot, UMR CNRS 7154, 1 rue Jussieu, 75238, Paris, Cedex, France.
authors.forename: Pascale
authors.initials: P
authors.lastname: Louvat
authors.affiliation: Institut de Physique du Globe de Paris, Sorbonne Paris Cité, Université Paris-Diderot, UMR CNRS 7154, 1 rue Jussieu, 75238, Paris, Cedex, France.
authors.forename: Julien
authors.initials: J
authors.lastname: Moureau
authors.affiliation: Institut de Physique du Globe de Paris, Sorbonne Paris Cité, Université Paris-Diderot, UMR CNRS 7154, 1 rue Jussieu, 75238, Paris, Cedex, France.
authors.forename: Jérôme
authors.initials: J
authors.lastname: Gaillardet