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 5 Retention times (Rt_stds) of monoaromatic hydrocarbons obtained by SBSE-TD-GC-MS analyses of a standard mixture (BTEX at 10 μg/L)

*Compounds*	*Molecular formula*	Rt _stds *(min)*	Rt _fluids *(min)*
toluene (T)	C7H8	3.28	3.26
ethylbenzene	C8H10	4.33	4.34
p-xylene / m-xylene	C8H10	4.45	4.43
o-xylene	C8H10	4.74	4.71
styrene	C8H8	4.74	4.71
isopropylbenzene	C9H12	5.10	-
n-propylbenzene	C9H12	5.49	-
1,3,4-trimethylbenzene	C9H12	5.61	-
tert-butylbenzene	C10H14	5.96	-
1,3,5-trimethylbenzene	C9H12	6.00	-
sec-butylbenzene	C10H14	6.21	-
paraisopropyltoluene	C10H14	6.39	-
n-butylbenzene	C10H14	6.81	-

Detection of the compounds was achieved using ions m/z 91, 103.9, 104.9, 120 and 133.9. The NIST08 library was used for identification. Retention times (Rt _fluids) obtained in hydrothermal fluids samples of this study are given for direct comparison.

ISSN: 1467-4866