Dataset: Brault 2014: Compound-specific Nitrogen in sperm whale dentin
Deployment: lab_UCSC_Koch

Materials and methods for analysis are described in detail in the text. Briefly, a homogenized sample of sperm whale dentin was split into sub-samples. Three received "Conventional" extractraction (decalcification with 0.5N HCl, rinsing with water to neutrality, freeze-drying) and three were not treated ("Raw"). Samples were hydrolyzed with 6 N HCl for 20 h at 110°C, then trifluoroacetic anhydride (TFAA) derivatives were prepared. Samples were analyzed for amino acid carbon and nitrogen isotope composition on a Thermo Trace gas chromatograph coupled to a Thermo Finnigan DeltaPlus XP isotope ratio mass spectrometer. Details on columns used, injection and furnace ramp parameters are presented in the paper. The amino acid δ15N values were determined from the measured values of the amino acid with corrections based on an amino acid mixture standard for which isotopic values had been independently determined by offline elemental analyzer analysis. Using this approach, isotopic values of 12 amino acids could be reproducibly quantified: alanine (Ala), glycine (Gly), threonine (Thr), serine (Ser), valine (Val), leucine (Leu), isoleucine (Ile), proline + hydroxyproline (Pro+), aspartic acid + asparagine (Asp), glutamic acid + glutamine (Glu), phenylalanine (Phe), and lysine (Lys). The amino acid molar percentages (Mol %) were determined from the peak areas using an external standard approach and based on the amino acid standard versus sample peak areas. *, isotopic value based on one injection; **, isotopic mean and stdv based on two injections.