Establishment of long-term preservation for dimethyl sulfide by the solid-phase microextraction method.

Area of Science:

• Marine chemistry
• Climate science
• Analytical chemistry

Background:

• Dimethyl sulfide (DMS) from marine life impacts climate radiative forcing.
• Traditional onboard ship analysis (purge and trap, P&T) for seawater DMS is complex, limiting spatiotemporal variability data.
• Solid-phase microextraction (SPME) offers a simpler alternative for DMS analysis.

Purpose of the Study:

• To assess the long-term preservation capability of DMS in seawater using SPME.
• To evaluate the influence of salinity on SPME measurements of DMS.
• To validate the SPME method for open ocean DMS surveys.

Main Methods:

• Long-term preservation of seawater samples containing DMS in liquid nitrogen (-196°C) for 20 days.
• Determination of DMS preservation rates.
• Estimation of the distribution coefficient to assess salinity effects on SPME.
• Comparison of DMS concentrations between preserved and unpreserved samples using SPME.

Main Results:

• A high preservation rate of 94.7 ± 4.4% for DMS was achieved over 20 days in liquid nitrogen.
• Salinity was found to have a minor influence on oceanic DMS measurements (0.1 nM/% sal).
• No significant differences were observed between preserved and unpreserved DMS samples (r = 0.99), validating the method.

Conclusions:

• SPME coupled with liquid nitrogen preservation is a viable method for long-term storage of DMS in seawater.
• The SPME method is suitable for open ocean surveys due to its simplicity and minimal salinity influence.
• This technique can improve the understanding of DMS spatiotemporal variability and its role in climate regulation.