Direct thermal extraction (DTE) is a thermal desorption technique in which a small amount of sample, typically 10-50 mg, is placed in an empty fritted thermal desorption tube or into a small vial (μ-vial) within an empty thermal desorption tube. The sample is then heated in a thermal desorption unit under a fl ow of inert gas, in order to release volatile and semi-volatile compounds. The analytes are trapped and fi nally determined by GC/MS. DTE requires little sample preparation and can be used for trace analysis of volatile and semivolatile organic compounds in solid or liquid samples. Exhaustive extraction conditions can be developed for an analyte by optimizing temperature, fl ow rate and extraction time. Calibration and quantifi cation can be performed by externally spiking standards onto Tenax-TA® fi lled sorbent tubes. This study describes the use of the GERSTEL MPS with CIS, and TDU for the analysis of volatile and semivolatile compounds in solid and liquid samples.