Delta 5 advantage ms

Specimens selected all had excellent preservation conditions, and no weathered or fragmented dental specimens were considered. Teeth were cleaned using air-abrasion. Sample of enamel powder (6 mg) was taken from buccal edge using diamond-tipped burr drill. It was washed in 1.5% NaClO for 60 min, rinsed, then centrifuged. It was then washed with acetic acid (0.1 M) for 10 min and rinsed. Residue was lyophilised for 24 h, then set to react with H₃PO₄ and gases were measured for stable carbon and oxygen ratios using GasBench II (Thermo) coupled with Delta V Advantage MS (Thermo). Values were compared against International Standards: IAEA-603 (δ¹³C = 2.5; δ¹⁸O = −2.4); IAEA-CO-8 (δ¹³C = −5.8; δ¹⁸O = −22.7); USGS44 (δ¹³C = −42.2), and in-house standard MERCK (δ¹³C = −41.3; δ¹⁸O = −14.4). Measurement error of MERCK standard c was ±0.1‰ for δ¹³C and ±0.2‰ for δ¹⁸O. Overall precision of measurements through repeat extracts from an in-house bovid tooth enamel standard c was ±0.2‰ for δ¹³C and ±0.3‰. Obligate or non-obligate drinking status was inferred from the range of δ¹⁸O as per references^{72 (link)–74 (link)}.