Characterisation of dissolved organic compounds in hydrothermal fluids by stir bar sorptive extraction - gas chomatography - mass spectrometry. Case study: the Rainbow field (36°N, Mid-Atlantic Ridge)

Table 3 Retention times (Rt _stds ) of C _8:0 -C _20:0 carboxylic acids obtained by SBSE-TD-GC-MS analyses of a standard mixture (50 μg/L)

Compounds	Molecular formula	Rt _stds (min)	Rt _fluids (min)
octanoic acid	C8H16O2	8.30	8.24†
nonanoic acid	C9H18O2	9.47	9.43*
decanoic acid	C10H20O2	10.61	10.52*
undecanoic acid	C11H22O2	11.68	-
dodecanoic acid	C12H24O2	12.67	12.58*
tridecanoic acid	C13H26O2	13.59	-
tetradecanoic acid	C14H28O2	14.44	14.41*
pentadecanoic acid	C15H30O2	15.24	15.23†
hexadecanoic acid	C16H32O2	16.02	16.12*
heptadecanoic acid	C17H34O2	16.78	-
octadecanoic acid	C18H36O2	17.65	17.61*
nonadecanoic acid	C19H38O2	18.27	-
eicosanoic acid	C20H40O2	-	-

Detection of the compounds was achieved using ions m/z 60 and 73. The NIST08 library was used for identification. Retention times (Rt _fluids) obtained in hydrothermal fluids are given for direct comparison: * This study, † [13].

ISSN: 1467-4866