Ciguatera Fish Poisoning is the world‘s largest food poisoning. The US FDA recommends an acceptable dose of 0.01 µg CTX1B equivalent/kg. The FDA level of sensitivity detection is possible by using LC/MS/MS equipment of one manufacturer, and a method has been reported to detect [M+Na]⁺ > [M+Na]⁺. In this study, we found a highly sensitive method for the detection of ciguatoxins, [M+Na]⁺ >[M+Na]⁺ or [M+Li]⁺ > [M+Li]⁺, by adding very small amounts of alkali metals such as Na⁺ or Li⁺ to the mobile phase. This method suggests that CTXs FDA level detection and high separation chromatography may be able to achieve for LC-MS from any manufacturer.