Stearoyl-L-carnitine (Standard), an acylcarnitine involved in fatty acid metabolism, is an endogenous metabolite of the body and serves as a metabolic biomarker for both early-onset and late-onset preeclampsia. Stearoyl-L-carnitine (Standard) can be used as a metabolic biomarker for early and late-onset preeclampsia and can be used for quantitative analysis, study of metabolic pathways and diagnosis of related diseases.