Determination of dimethylsulfoniopropionate and dimethylsulfoxide in Posidonia oceanica leaf tissue

In order to investigate the possible use of the dimethylsulfoniopropionate (DMSP) and dimethylsulfoxide (DMSO) ratio as a stress indicator of Posidonia oceanica a method for the determination of these quantities was developed for this type of material. The method relies on gas chromatography with headspace technique, instead of the purge-and-trap technique commonly used. The method allows the determination of both DMSP and DMSO on the same sample.
This method allows to quantify DMSP, DMSO and DMSP:DMSO ratio for calibration curves with a coefficient of variation around 2% and a relative error around 2% and within the ranges natural variability of DMSP and DMSO in P. oceanica leaf tissue. Preliminary tests showed that DMSP in P. oceanica leaf tissue ranged from 20 to 200 mmol g 1 of fresh weight (FW) and 2 to 5 mmol gfw
1 for DMSO. The DMSP:DMSO ratio ranged from 2 to 40. The quantifications were conducted with different mixtures of DMSP and DMSO by measurements of DMSP and DMSO in the same sample
of P. oceanica leaf tissue.