Journal of Paleolimnology

, Volume 18, Issue 4, pp 335–350

Mass Spectrometry and reverse phase HPLC techniques for the identification of degraded fossil pigments in lake sediments and their application in palaeolimnology

Authors

  • Dominic A. Hodgson
    • Department of Plant ScienceUniversity of Tasmania
  • Simon W. Wright
    • Australian Antarctic Division
  • Noel Davies
    • Central Science LaboratoryUniversity of Tasmania
Article

DOI: 10.1023/A:1007943119392

Cite this article as:
Hodgson, D.A., Wright, S.W. & Davies, N. Journal of Paleolimnology (1997) 18: 335. doi:10.1023/A:1007943119392

Abstract

Accurate identification of fossil pigments is essential if they are to be used as biomarker compounds in palaeolimnological studies. In recent years High Performance Liquid Chromatography (HPLC) has greatly enhanced the efficiency with which fossil pigments can be characterised and quantified. Using HPLC, undegraded pigments are typically identified through retention times, absorbance spectra and co-chromatography with authentic reference standards. However, lake sediments may also contain degraded pigments for which there are often no standards, and which may be difficult to identify using HPLC alone. In this study, we submitted HPLC fractions of fossil pigments and pigment derivatives collected from a meromictic lake in south west Tasmania, to a combination of Mass Spectrometry (MS) techniques including Electron Impact (EI) and static Liquid Secondary Ion MS (LSIMS) to identify their molecular ion characteristics and organic chemical composition. Mass Spectrometry permitted the detection of specific mass ions which were used to verify the identity of pigments and their derivatives. These included five carotenoids, chlorophyll a and derivatives, three previously described bacteriochlorophyll c derivatives with molecular weights of 770, 784, and 802, and two undescribed derivatives of bacteriochlorophyll c with molecular weights of 766 and 788. With these improved identifications we speculate on the pathways and modes of pigment degradation in the lake and asses the value of the degraded pigments as biomarkers. The use of MS permitted the identification of a greater number of signature pigments of algal and bacterial communities thus increasing the palaeolimnological value of the sediments. These methods are best applied in fossil pigment studies where there are a large number of unknown pigments and pigment degradation products, and where there are no authentic standards for co-chromatography. Practical suggestions for pigment MS are included in the discussion.

palaeolimnology pigments massspectrometry HPLC carotenoids chlorophylls bacteriochlorophylls biomarkers

Copyright information

© Kluwer Academic Publishers 1997