Abstract: The present invention provides an apparatus and method for trapping and injecting a fluid sample (liquid or gas) at high temperature and pressure without any sample loss. Here, a sample is flowed into an aperture in the valve body and then into a sample chamber. The sample chamber is mounted in a slidable stem and once the sample is in the sample chamber, the stem is moved to a position to seal off the sample. Once the sample is trapped, the valve is moved to a chromatograph (while maintaining the sample at pressure and temperature), flushed with a carrier gas, and the stem is moved to open the sample chamber to the gas. This flushes the sample and moves it to the chromatograph.