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:

Sorting out Semiconducting Single-Walled Carbon Nanotube Arrays by Washing off Metallic Tubes Using SDS Aqueous Solution. Semiconducting single-walled carbon nanotube (s-SWNT) arrays are produced via a procedure analogous to a surfactant-assisted decontamination process. Aligned individual SWNT arrays grow on a quartz surface as a mixture of metallic SWNTs (m-SWNTs) and s-SWNTs. They are immersed in a sodium dodecyl sulfate (SDS) solution, and the SDS molecules selectively adsorb onto m-SWNTs. This SDS coating minimizes the interaction between m-SWNTs and the substrate, thus the m-SWNTs are easily washed off during ultrasonication while the s-SWNT arrays remain on the substrate. The percentage of s-SWNTs in the arrays can be higher than 90%.
{"Chemical": ["sodium dodecyl sulfate", "Carbon", "carbon", "quartz", "SDS"]}