You will be shown an abstract from a biomedical research paper. Given this abstract, your task is to extract all unique entities of the following types: ["Chemical"].

Please return the output as a JSON object of the format: {"Chemical": ["Arsenic", ...]}. The keys should be entity types and values should be lists of extracted entities belonging to the corresponding type. If you cannot find entities belonging to a specific type, the value should be [].

Only output the JSON object and do not include any additional text.

Abstract:

Determination of 10 ginsenosides in Panax ginseng of different harvest times based on HPLC fingerprints and principal component analysis. A combinative method of HPLC fingerprinting and quantitative determination was successfully applied to monitor dynamic accumulation of ginsenosides in five-year-old Panax ginseng roots from different harvest times. The optimal chromatographic conditions were achieved on a C18 column with gradient elution using acetonitrile and 1 mmol · L(-1) KH2PO4 buffer solution at 203 nm. The result indicated that the contents of total ginsenosides showed significant variations, and a decrease tendency appeared in the growth period of the fifth year.
{"Chemical": ["ginsenosides", "KH2PO4"]}