This invention demonstrates a micro-machined sample injection unit which consists of a T-shaped channel operated with a simple setup involving a single 3-way fluidic valve, a micro-pump for sample loading and a carrier gas supply for subsequent analysis of the volatile organic compounds (VOCs). The innovative sample injection technique described herein requires the loading time of a few seconds duration and produces very sharp and repeatable sample pulses (full-width-at-half-maximum - 200 ms) at the carrier gas flow rate compatible with efficient chromatographic separations. Moreover, the invention describes the monolithic integration of sample injection unit with the micro separation column (µSC) and the detector (micro helium discharge photoionization detector) using a two step planar fabrication process. The comprehensive characterization of the integrated chip shows that a wide variety of VOCs ranging from 110 ·c - 216 ·c in boiling points can be analyzed quickly (<l min) through optimization of flow and temperature programming conditions. Moreover, the analysis of four VOCs at the concentration level of 1 parts-per-million in aqueous sample (which corresponds to headspace concentration in lower parts-per-billion regime) was performed in a rapid manner requiring only 6 s of sampling time. The invention can be further extended to integrate the sample injector with a detection unit to realize a total VOC analyzer.