Determination of phosphine in biogas and sludge at ppt-levels with gas chromatography-thermionic specific detection

A gas chromatographic (GC) system to measure free phosphine in biogas and matrix bound phosphine in manure and sludge is presented. The system consists of a sample preconcentration trap filled with glass beads, connected with a capillary GC equipped with a thermionic specific detector. With a trap temperature as low as -155 degrees C, a sampling flow of 20 ml/min and a typical total sample volume of 100 ml, free phosphine concentrations in the low ng/m3 range and matrix bound phosphine in the low ng/kg dry matter range, can be accurately and reproducibly determined.