The Wasson-ECE Gas Auto-sampler (AS100B) automates the sampling of multiple sample cylinders for analysis on a gas chromatograph (GC). The auto-sampler oven accommodates up to twelve 500 mL or nine 1-liter sample cylinders with a maximum temperature of 135°C. The software allows users to enter sample information, adjust software parameters, log sample injection times, and create data reports. The Gas Auto-sampler is a stand-alone device that delivers samples to the GC through a heated bridge, eliminating cold spots along the sample path. The system performs a purge and vacuum step between each sample injection to minimize cross-contamination (typically less than 50 ppm).