5 imp

Durashell AA analysis kit contained internal standard and 17 kinds of amino acid standard, which was purchased from Agela Technologies (Tianjin, China). Oxalic acid, tartaric acid, lactic acid, citric acid, succinic acid, hydrochloric acid (HCl), disodium hydrogen phosphate dodecahydrate (Na₂HPO₄•12H₂O), potassium dihydrogen phosphate (KH₂PO₄), phosphoric acid (H₃PO₄) (all AR grade), and malic acid (BR grade) were obtained from Sinopharm Chemical Reagent Co. (Shanghai, China). Guanosine 5′‐monophosphate (5′‐GMP) disodium salt hydrate, 5′‐IMP, 5′‐AMP, and cytidine 5′‐monophosphate (5′‐CMP) were purchased from Sigma‐Aldrich (St. Louis, Mo., U.S.A.). Methanol, sulfosalicylic acid, and acetonitrile (ACN) (all HPLC‐grade) were purchased from Fisher Scientific (Shanghai, China). The ultrapure water was purchased from Hangzhou Wahaha Group Co., Ltd. (Hangzhou, China). Buffer salt I (0.05 mol/L KH₂PO₄) was prepared by dissolving 6.80 g KH₂PO₄ in 1 L water. Buffer salt II (0.01 mol/L KH₂PO₄) was prepared by dissolving 1.36 g KH₂PO₄ in 1 L water and then adjusted to pH 2.8 by 1 mol/L H₃PO₄.

Sheep tail fat (Sunit sheep) was purchased from Xilingol league, Inner Mongolia. Dried ginger (Shandong Province), cassia (Guangxi Province), nutmeg (Guangdong Province), white pepper (Guangxi Province) and prickly ash (Guangxi Province) were purchased from Yonghui supermarket, Beijing. Oxalic acid, ascorbic acid, citric acid, succinic acid, lactic acid, hydrochloric acid (HCl) and phosphoric acid (H₃PO₄) were purchased from Sinopharm Chemical Reagent Co. (Shanghai, China). Cytidine 5′-monophosphate (5′-CMP), 5′-GMP, 5′-AMP and 5′-IMP were purchased from Sigma-Aldrich (St. Louis, MO, USA). Monopotassium phosphate (KH₂PO₄), sodium dihydrogen phosphate dodecahydrate (Na₂HPO₄·12H₂O) and sodium borate decahydrate (Na₂B₄O₇·10H₂O) were purchased from Alfa Aesar (Ward Hill, MA, USA). All these chemicals are analytical grade with purity ≥ 98%. HPLC grade methanol, acetonitrile and isopropanol were purchased from Fisher Scientific (Shanghai, China). Ultra-pure water was supplied by Hangzhou Wahaha Group Co., Ltd. (Hangzhou, China).