This method is for determining individual C4 components andtotal C6 components in liquefied hydrocarbon mixtures typicallyfound in C4 Olex process streams. All C4 olefins including 1-buteneand isobutylene are separated while C6, along with any C5 and/orC7+ hydrocarbons that may be present, are determined as acomposite. The lower limit of detection for a single component is0.05 mass-%.