Delta 5 advantage isotope ratio mass spectrometer

Stable isotope analyses were performed at the School of Geosciences, University of South Florida, using the equilibration method on a Thermo Delta V Advantage Isotope Ratio Mass Spectrometer. The results were normalized to the VSMOW-SLAP scale and reported in the conventional δ notation, in ‰ (per mil) against VSMOW (Vienna Standard Mean Ocean Water), with precision better than ±0.2‰ and ±1‰ for δ¹⁸O and δ²H, respectively (Supplementary Dataset 3).

Prior to analyses of P and N concentrations in plant tissues, the dried samples of shoots and roots were ground to powder using a ball mill (MM200, Retsch, Haan, Germany). To determine the P concentration in plant tissues, milled samples of shoots and roots (100 mg each) were incinerated in a muffle furnace at 550°C for 12 h. The resulting ash was combined with 1 mL of concentrated (69%) HNO₃ and briefly heated to 250°C on a hot plate. The materials was then transferred to volumetric flasks through a filter paper and brought up to 50 mL with ultrapure (18 MΩ) water. Phosphorus concentration in the extracts was then measured by colorimetry at 610 nm using a Pharmacia LKB Ultrospec III spectrophotometer by the malachite green method (Ohno and Zibilske, 1991 (link)).
The N concentrations and N isotopic composition in shoots and roots were measured using a Flash EA 2000 elemental analyzer coupled with a Delta V Advantage isotope ratio mass spectrometer (Thermo Fisher Scientific, Waltham, MA, USA).
Total N and P contents were calculated from SDW and RDW data and the concentrations of the corresponding elements in shoot and root biomass, respectively. Additionally, mycorrhizal P-uptake response (MPR) and mycorrhizal N-uptake response (MNR) were calculated from the P contents of the plants (shoots and roots combined) similarly as described above for the MGR.

For measurement of the isotopic ratio of carbon-13 (δ¹³C) in snake rattles, mice and their ration, three samples weighing from 50 to 70 μg were inserted into capsules maintained in a refrigerator at +4°C, in the laboratory of the Stable Isotopes Center of UNESP, Botucatu, SP. The employed methodology was proposed by Tieszen et al. [11 (link)], with adaptations by Ducatti et al.[6 (link)]. The isotopic ratios of ¹³C/¹²C were measured in a Delta V Advantage Isotope Ratio Mass Spectrometer (Thermo Fisher Scientific, USA). Isotopic ratio values were expressed as delta per thousand (δ) relative to the PDB international standards for ¹³C.