An inlet splitter is described in which injection, vaporization, mixing, expansion and splitting occur in a glass insert. The insert is removable for cleaning and silylation; the latter can be accomplished in situ. Data are presented indicating a high degree of reproducibility over split ratios ranging from 1:100 to 1:750. At split ratios lower than ca. 1:200, discrimination factors are evident. At split ratios above this value, the integrator response for individual components of the C6-C19 hydrocarbon test mixture compared favorably with values obtained with a packed column operating with no splitting, and with calculated theoretical values.