1H-NMR Spectra of Pelagic Sargassum Specimens under Different Flash-Freeze Timing and Cryogenic Storage Conditions

About the data set origin

The dataset comprises 60 1H-NMR spectral FID files of pelagic Sargassum specimens, including S. fluitans III (labeled "flu3" in the sample ID), S. natans I (labeled "nat1"), and S. natans VII (labeled "nat8"). The specimens were collected from three sites on the south Mexican Caribbean coast: Mahahual (labeled "Ma"), Xcalak (labeled "Xk"), and Xahuayxol (labeled "Xa"). The experimental design includes a treatment condition based on flash-freezing timing: the fresh group (labeled d00) and the lab group (labeled d01). The fresh group was flash-frozen on the shore and stored under cryogenic conditions, while the lab samples were flash-frozen upon arrival at the laboratory facilities. The fid file sample IDs are in the text file Sample_List_Sar23.txt. The sample IDs are listed below in Table 1. 

About the Equipment and Data Acquisition

The NMR experiments were performed on a 600 MHz Varian-Agilent AR Premium Compact (14.1T). The metabolite extraction process involved weighing approximately 100 mg of freeze-dried and ground tissue in a two ml microtube, adding 300 μl of CD3OD μl first and then 900 μl of D2O (0.05% TSP), producing a (3:1) mixture. The microtubes were then vortexed, sonicated for fifteen minutes, centrifuged for twenty minutes at 15 000 g, and transferred (600 μl) to a five mm NMR tube. The 1H-NMR spectra were recorded employing the PRESAT sequence with the following parameters: pulse width: 5.9 µs; relaxation time: 1 s; acquisition time: 3 s; number of transients: 64 with data collected in 65k data points (Hernández-Bolio et al. 2021). 

Table 1. Sample ID and size for the 1H-NMR data of the flash-freeze comparison.