Hplc grade ethanol etoh

HPLC-grade ethanol (EtOH) and dichloromethane were purchased from Merck (Merck Co., Darmstadt, Germany). The LC-MS-grade solvents acetonitrile (ACN), methanol (MeOH) and formic acid (FA) were purchased from Fisher Chemical (New Jersey, USA). Chemical standards of lutein, β-carotene, zeaxanthin, and lycopene were purchased from Sigma (St Louis, MO, USA); those of β-cryptoxanthin, all-trans-canthaxanthin, all-trans-fucoxanthin, all-trans-astaxanthin, violaxanthin and neoxanthin were obtained from ChromaDex (Santa Ana, CA). All other reagents and solvents were of high analytical grade unless otherwise stated. Water was obtained from arium® pro Ultrapure Water Systems (Sartorius, Goettingen, Germany). All solvents were degassed before use.

HPLC-grade ethanol (EtOH) and acetonitrile were obtained from Merck (Darmstadt, Germany). Formic acid was purchased from Aladdin Chemicals (Shanghai, China). Reference standard of salidroside was obtained from National Institutes for Food and Drug Control (Beijing, China). And 1,2,3,4,6-pentagalloyglucose was purchased from Chengdu Chroma-Biotechnology (Chengdu, China). The water was purified by a Milli-Q water purification system (Billerica, MA, USA). The roots and rhizomes of 159 batches of samples were collected from China and included 131 batches of Rhodiola crenulata, 18 batches of Rhodiola serrata, 4 batches of Rhodiola yunnanensis, and 2 batches of Rhodiola rosea, Rhodiola kirilowii, Rhodiola fastigiata, respectively. All samples were authenticated by the traditional Chinese medicine testing department (Shenzhen Institute for Drug Control, Shenzhen, Guangdong, China). The detailed sample information is listed in Table 2.