Organotin compounds: Development of an HPLC-ICP-MS method for the determination of eleven organotin species in workplace air

Organotin compounds (OTC) rank among the most used organometallic compounds and have been utilized in various industrial sectors for several decades. Due to their high human and ecotoxicity, their use is already largely regulated. At workplaces, OTC can be released as vapors or dust particles and can be absorbed by inhalation or skin contact. Occupational exposure thus represents a great risk for the absorption of OTC for employees. Methods for OTC speciation in workplace air monitoring currently do not exist. This study describes the development of a separation method for eleven regulated OTC via High-performance liquid chromatography coupled to inductively coupled plasma (HPLC-ICP-MS). The developed method allows a near baseline separation of the target compounds MMT, MBT, MOT, MPhT, DMT, DBT, DPhT, TMT, TBT, TPhT and TTMT within 22 minutes via Reverse Phase (RP)-HPLC. The separation is achieved by means of a C18 and a ternary solvent and flow rate gradient using methanol, acetonitrile and ultapure water + 6 % (v/v) acetic acid + 0.17 % (m/v) alpha-tropolone. Over the course of this study, it became apparent that some OTC are thermally unstable and cross reactive. To that effect it was possible to prove the formation of two reaction products in mixed OTC solutions. These effects are to be further examined in the development of suitable sampling and sample preparation methods for workplace air samples. The suitability of the method was successfully tested in initial comparative measurements on workplace samples.