sorbentrør

A sorbentrör, or sorbent tube, is a small, refillable glass or inert tube used to collect volatile and semi-volatile organic compounds from air. As air is drawn through the tube, target analytes are trapped by the sorbent material, enabling subsequent laboratory analysis. Sorbent tubes are widely used in occupational hygiene, environmental monitoring, and research to characterize air quality and exposure.

Construction and materials vary, but most tubes are 6 to 9 cm long and contain a sorbent bed held between two frits. They can be single-bed or multi-bed (layered) configurations. Common sorbents include activated carbon, graphitized carbon black, and polymer adsorbents such as Tenax variants, Carbotrap, Carbopack, and Carboxen. Multi-bed tubes may combine different materials to extend the range from low to high volatility and improve breakthrough resistance.

Operation and handling involve pulling a known volume of air through the tube at a calibrated flow rate for a defined sampling period. The analytes are retained on the sorbent as air passes through. After sampling, tubes are analyzed by thermal desorption followed by gas chromatography or GC–MS, or by solvent desorption with subsequent chromatography. Thermal desorption offers solvent-free, direct transfer of analytes to the instrument.

Storage and QA considerations include keeping tubes cool and protected from light, using them within recommended hold times, and preventing contamination during handling. Proper calibration, breakthrough assessment, and desorption efficiency testing are essential for reliable results. Sorbent tubes are standard tools for monitoring workplace and environmental air for a broad range of VOCs and SVOCs.