Evaluation of various solid adsorbents for sampling trace levels of methanethiol

The efficiency of fourteen solid adsorbent sampling tubes in trapping trace levels of methanethiol was evaluated. A thermal desorption-gas chromatographic method for the accurate separation of methanethiol from other simultaneously collected reduced volatile sulfur gases was developed. Trapping experiments demonstrated that silica gel (96.4% recovery) and molecular sieves (86.2% recovery) were the best solid adsorbent materials for collecting methanethiol when the sweep gas is dry. Using a calcium chloride drying tube, silica gel provided similar results (i.e., better than 95% recovery values) when the sweep gas contained moisture (i.e., normal field sampling conditions). Molecular sieves also were shown to be acceptable adsorbent materials for trapping methanethiol under moist conditions (73.9% recovery). Recovery values showed no significant changes during 36 h storage or using different flow rates (between 10–80 ml/min).