Speciation Measurements of Butyltins: Application to Controlled Release Rate Determination and Production of Reference Standards

This paper describes methods and results of the determination of release rates for organotin species released from organotin impregnated wood pilings. The analytical method consists of simultaneous extraction/hydridization of aqueous leachate samples, with organotin speciation by gas chromatography coupled with tin selective flame photometric detection (GC-FPD). The sensitivity of the FPD detector to the butyltin family of organotins is 0.1 to 0.2 ng, depending on the species. Chromatographic separation of the butyltins provides speciation of mono- through tetrabutyltin within a 15 min chromatogram, with the additional capability of identifying any methylbutyltin compounds that may be present in the sample. Water samples were collected from the piling leaching tanks immediately upon immersion of the pilings and continued to be collected for approximately 1 year. Speciation and release rate data were obtained on both the early, first order stage of organotin release, and the latter, zeroth order phase of controlled release. Instrument calibrations were performed using a specially prepared organotin research material.