A gasoline blend spot sampling system and method including an adjustable volume mechanism for retaining an adjustable volume of gasoline for sampling, a coolant system integrated with the adjustable volume mechanism, and a sample collection assembly using a blunt-end tube for use with an open-mouthed bottle. Various three-way valves are actuated to route gasoline through various stages of a sampling process, from a gasoline fast loop to a purge loop to a gasoline capture stage to a sample bottling stage.