“…API (American Petroleum Institute) gravity as a recognized oil specific gravity index, can roughly measure the quality of oil, whereby if the API gravity is higher, it means the product can refine more refined petroleum products, and also suggests a higher quality of the product. 56 It is possible that in the actual petroleum refining process, gasoline may be mixed with some kerosene, which may affect the product quality, and there may be some adulterated gasoline, resulting in many defective products. Therefore, it is necessary to develop some sensors to detect the quality of petroleum.…”