Hplc grade

The urine samples were analyzed at the collaborative laboratory of East China University of Science and Technology (Shanghai, China). We measured urinary concentrations of total BPA (free plus conjugated species) using modified high-performance liquid chromatography (HPLC) as described by He et al[21 (link)]. Briefly, urine samples were treated with phosphorous acid buffer/ β-glucuronidase for hydrolyzation, and were subsequently extracted twice using ether (HPLC grade, Dikma). The supernatants were collected and evaporated with nitrogen gas. The residue was dissolved in 60% acetonitrile and analyzed using HPLC equipment. The limit of detection (LOD) of BPA in the present study was 0.12μg/L.BPA levels below the LOD were assigned a value of LOD divided by the square root of 2, based on a conventionally accepted practice.[22 ] Adjustment for creatinine was performed to account for urine volume.

HPLC-grade, LC-MS-grade acetonitrile (ACN) and methanol (MeOH) were purchased from Dikma Co., Ltd. (Massier Lane, Foothill Ranch, CA, USA). Normal saline was obtained from Qidu Pharmaceutical Co., Ltd. (Shandong, China). Hydrogen trifluoride triethylamine, tetrahydrofuran (THF), tertiary butyl dimethyl chlorosilane (TBSCl), dimethylaminopyridine (DMAP), imidazole, triethylamine, and ammonium acetate were obtained from Macklin Biochemical Technology Co., Ltd. (Shanghai, China). Formic acid, phosphoric acid, N,N′-carbonyldiimidazole (CDI), dicyclohexylcarbodiimide (DCC), dimethyl formamide (DMF), and isobutyric acid were purchased from Aladdin Biochemical Technology Co., Ltd. (Shanghai, China). GS441524 (GS441, MW291.3) and 6,7-dimethyl-2,3-bis(2-pyridyl) quinoxaline (QX, MW312.4) were obtained from APExBIO Co., Ltd. (Houston, TX, USA) and JiSiEnBei International Business Co., Ltd. (Hong Kong, China), respectively.