Fast Liquid Chromatography Coupled with Tandem MassSpectrometry for the Analysis of Vanillic and Syringic Acids in IceCores

The development of new analytical systems and theimprovement of the existing ones to obtain high-resolutionmeasurements of chemical markers in samples from ice cores, isone of the main challenges the paleoclimatic scientific community isfacing. Different chemical species can be used as markers fortracking emission sources or specific environmental processes.Although some markers, such as methane sulfonic acid (a proxy ofmarine productivity), are commonly used, there is a lack of data onother organic tracers in ice cores, making their continuous analysisanalytically challenging. Here, we present an innovative combina-tion of fast liquid chromatography coupled with tandem massspectrometry (FLC-MS/MS) to continuously determine organicmarkers in ice cores. After specific optimization, this approach wasapplied to the quantification of vanillic and syringic acids, two specific markers for biomass burning. Using the validated method,detection limits of 3.6 and 4.6 pg mL-1for vanillic and syringic acids, respectively, were achieved. Thanks to the coupling of FLC-MS/MS with the continuousflow analytical system, we obtained one measurement every 30 s, which corresponds to a samplingresolution of a sample every 1.5 cm with a melting rate of 3.0 cm min-1. To check the robustness of the method, we analyzed twoparallel sticks of an alpine ice core over more than 5 h. Vanillic acid was found with concentrations in the range of picograms permilliliter, suggesting the combustion of coniferous trees, which are found throughout the Italian Alps.

Automated summary

The development of new analytical systems and improvement of existing ones to obtain high-resolution measurements of chemical markers in ice cores is a major challenge in the paleoclimatic scientific community. This study presents an innovative combination of fast liquid chromatography coupled with tandem mass spectrometry (FLC-MS/MS) for continuous determination of organic markers in ice cores. The method achieved low detection limits and high sampling resolution, allowing for the detection of specific organic markers and suggesting the presence of forest fires.