Cayman's Oxysterol Derivatization MaxSpec? Kit is designed for the sensitive detection and relative quantitation of oxysterols in biological samples. This is achieved through enzyme-assisted derivatization utilizing d0/d5 labeled Girard's P reagent to give GP hydrazones. The instrumental response of the derivatized oxysterols is significantly improved due to the presence of a positively charged quaternary nitrogen group in the labeled and unlabeled GP hydrazones. Included in this kit are the essential reagents to derivatize oxysterols in mixtures for sensitive and comparative LC-MS analysis.