Quantification of low molecular weight fatty acids in cave drip water and speleothems using HPLC-ESI-IT/MS — development and validation of a selective method

Abstract

This study presents a novel method for the analysis of low molecular weight (LMW) fatty acids in cave drip water and speleothems. The method development included optimization of sample preparation procedures, e.g., blank reduction, solid phase extraction, concentration of extracts as well as liquid chromatography coupled to electrospray ion-trap mass spectrometry (HPLC-ESI-IT/MS) measurement parameters. Retention times for five analytes (lauric acid, myristic acid, palmitic acid, stearic acid and arachidic acid) were between 5 and 13.5 min. Spiking experiments were performed to accomplish external calibrations which ranged from 12.5 to 75 ng per spiked water sample. The correlation coefficient ranged from 0.9558 to 0.9989. Inter-batch precision, expressed as the relative standard deviation of three replicates, was <7 %. Limits of detection ranged from 0.77 to 55.97 ng for the diverse analytes; obtained recoveries varied from 30 to 103 %. For a first application, cave drip water and stalagmite samples from Herbstlabyrinth-Adventhöhle cave system were analyzed. Concentrations ranged from 38.37 to 9,982.54 ng L(-1) for water samples and 2.52 to 1,344.96 ng g(-1) for the stalagmite. Thereby, the different fatty acids showed a distinctive variation. Whereas shorter-chained fatty acids exhibited similarities, arachidic acid showed opposite trends. Diverse correlations were found, which could improve the understanding of different organic sources of the lipids transported by drip water and preserved in speleothems. This new method provides a more selective extraction process, particularly adjusted to LMW fatty acids and therefore reduces the required sample size. Furthermore, it is applicable to stalagmite as well as cave drip water samples.

Geochemical mapping of organic carbon in stalagmites using liquid-phase and solid-phase fluorescence

“…Since studies first demonstrated the presence of organic matter (OM) entrapped in calcite (Baker et al, 1996;Ramseyer et al, 1997), a number of organic components of speleothems being used as proxies for investigating changes in soils, vegetation, and climate (e.g., Baker et al, 1998;Blyth & Schouten 2013;Blyth et al 2011;Blyth et al, 2014;Bosle et al, 2014;Li et al, 2014;Perrette et al, 2005, Perrette et al, 2008Webb et al, 2014).…”

Analysis of biogenic carbonyl compounds in rainwater by stir bar sorptive extraction technique with chemical derivatization and gas chromatography‐mass spectrometry

“…The comparisons between the SBSE derivatization technique and other previously reported methods for measuring aqueous carbonyls in terms of LOD are listed in Table . The LODs of this SBSE technique for carbonyl measurements are lower than those of GC–ECD , and SPME–HPLC–UV , by 10 to 100 times and close to those of SBSE–HPLC–MS and solvent extraction GC–ECD techniques .…”

“…Peaks in GC chromatograms are formaldehyde (peak 1), PFBHA (peak 2), ethanal (peaks 3 and 4), acetone (peak 5), propanal (peaks 6 and 7), propenal (peak 8), butanal (peak 9), isobutenal (peak 10), butanone (peak 11), 2-hydroxy ethanol (peaks 12 and 13), pentanal (peak 14), hexanal (peaks 15 and 16), GLY (peaks 17, 18, and 19), and MGLY (peaks 20 and 21), respectively methods for measuring aqueous carbonyls in terms of LOD are listed in Table 4. The LODs of this SBSE technique for carbonyl measurements are lower than those of GC-ECD [28], and SPME-HPLC-UV [29], by 10 to 100 times and close to those of SBSE-HPLC-MS [30] and solvent extraction GC-ECD techniques [31].…”

Characterisation of organic inclusions in stalagmites using laser-ablation-micropyrolysis gas chromatography–mass spectrometry

“…However, the focus on biomarkers extractable by wet chemistry from the carbonate means that most research to date has required relatively large sample sizes of calcite (1-100 g) ( [50,14,51,13,36]), compared to established inorganic geochemical proxies. Selected techniques published to date allow analysis of less than 1 g of calcite: thermochemolysis of lignin (0.5 g; [12,16]); one study of lipid biomarkers in an American stalagmite (0.3-0.5 g; [40]) amino acid analysis (25-120 mg, [35,15]); high performance liquid chromatography analysis of short chain fatty acids (0.5-3.5 g, [21]); and liquid chromatography-isotope ratio mass spectrometry (LC-IRMS) analysis of bulk organic isotopes (0.2 g; [18,19]). Of these, only LC-IRMS of bulk ı 13 C has so far been fully applied in a multi-proxy palaeoenvironmental reconstruction [19].…”