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:

The hidden quality gap in discovery. Progress made through technological advances in drug discovery can be undermined by problems with measurement equipment, but it is often difficult to detect the issues without a specific investigation. This article describes the fundamentals of measurement systems analysis and focuses on the issue of precision. Three case studies are given where measurement systems were found to be flawed when subjected to a systematic analysis, and examples of the approaches needed for correction are described.
{"Chemical": []}