title: Analytical methodology for TEX86 paleothermometry by high-performance liquid chromatography/atmospheric pressure chemical ionization-mass spectrometry.
abstract: The TEX86 is a recently proposed paleothermometer through which ancient seawater temperatures of up to 120 My ago can be reconstructed. It is based on the relative distribution of glycerol dibiphytanyl glycerol tetraethers as measured by high-performance liquid chromatography/atmospheric pressure chemical ionization-mass spectrometry (HPLC/APCI-MS). The aim of this study was to examine and improve several analytical aspects in the determination of this important proxy in environmental matrices. Comparison of TEX86 analysis using single ion mode (SIM) and mass scanning (m/z 950 to 1450) detection, respectively, revealed that SIM is up to 2 orders of magnitude more sensitive and that the TEX86 can be determined with a reproducibility of +/-0.004 or +/-0.3 degrees C using this method. Comparison of TEX86 values obtained with two different HPLC/APCI-MS set-ups revealed no significant differences. In addition, analysis of TEX86 of extracts obtained by Soxhlet, ultrasonic, and accelerated high-pressure extraction techniques also showed no significant differences between the methods. Our results suggest that TEX86 analysis by HPLC/APCI-MS is robust and can be determined with analytical errors comparable to those of other temperature proxies.
authors.affiliation: Department of Marine Biogeochemistry and Toxicology, Royal Netherlands Institute for Sea Research, P.O. Box 59, 1790 AB, Den Burg, Texel, The Netherlands. schouten@nioz.nl
authors.forename: Stefan
authors.initials: S
authors.lastname: Schouten
authors.forename: Carme
authors.initials: C
authors.lastname: Huguet
authors.forename: Ellen C
authors.initials: EC
authors.lastname: Hopmans
authors.forename: Michiel V M
authors.initials: MV
authors.lastname: Kienhuis
authors.forename: Jaap S Sinninghe
authors.initials: JS
authors.lastname: Damsté
mesh_terms: D002851:Chromatography, High Pressure Liquid / Q000379:methods; D019015:Geologic Sediments / Q000032:analysis*; D012680:Sensitivity and Specificity; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D013821:Thermometers; D013995:Time