N methyl n t butyldimethylsilyl trifluoroacetamide

The isotopic enrichment of lactate with [¹³C]-L-lactate was measured by gas chromatography-mass spectrometry in plasma samples deproteinized with perchloric acid and derivatized using N-methyl-N-(t-butyldimethylsilyl)-trifluoroacetamide (Sigma, St. Louis, MO, USA). Plasma [9,10³H]-oleate concentration was measured by extracting fatty acids from 0.5 mL of plasma in 3 mL of HCl-heptane-isopropanol (1 : 10 : 40) and counting the radioactivity of the organic phase with a liquid scintillation counter (model LS 6500; Beckman) while ³H₂O concentration, derived from [9,10-³H] oleate oxidation, was measured by counting the water phase. Myocardial substrate uptake, release, and oxidation were calculated as the arteriovenous concentration difference times CBF as previously described [19 (link)].

Sheep milk and cow milk used in this work were provided by commercial dairy farms and were frozen before use. Baby feces were donated and stored at −80 °C shortly after collection.
Chemicals used were as follows: KCl (99.5%), KH₂PO₄ (99.5%), MgCl₂(H₂O)₆, orthophosphoric acid (85%), and diethyl ether (98%) were sourced from BDH Laboratory Supplies, Dorset, England. NaCl (99.6%) and CaCl₂ (99%) were sourced from ThermoFisher Scientific, (Waltham, MA, USA). NaHCO₃ (99%) was sourced from JT Baker, (Phillipsburg, NJ, USA). Pancreatin (37452 FIP-U/mg) was sourced from AppliChem GmbH, (Darmstadt, Germany). D₂O (99.8%) was sourced from Cambridge Isotope Labs Inc, (Tewksbury, MA, USA). (NH₄)₂CO₃ (99%), pepsin, gastric lipase (20,000 U/mg), cysteine (97%), bile salts, ethylbutyric acid (98%), N-methyl-N-t-butyldimethylsilyltrifluoroacetamide (95%), and imidazole (99%) were sourced from Sigma-Aldrich, (St. Louis, MO, USA).