Trace speciation by HPLCGF AA for tin‐ and leadbearing organometallic compounds, with signal increases induced by transition‐metal ions

High‐performance liquid chromatography coupled with graphite furnace atomic absorption spectroscopy (HPLCGF AA) gives element‐specific detection of environmental samples containing trace amounts of organotin or organolead species. The direct GF AA of organotin and organolead species is subject to errors arising primarily from loss of analyte prior to atomization, probably through the formation of refractory carbides and of compounds or complexes that are volatile at low temperatures. Examples abound in the literature of signal suppression in the GF AA of organometallic species in environmental samples, and several furnace tube modifications have been developed to overcome this suppression. Here, the analyte and a modifier are co‐pipetted into a conventional furnace tube, from either a solution of analyte or an HPLC effluent. Oxides of transition metals (e.g. chromium, manganese, or tungsten) are shown to enhance both tin and lead signals, whereas chlorides do not, suggesting the low‐temperature formation of relatively involatile metal oxides or volatile metal chlorides, respectively. In the absence of modifier, GF AA signal intensities decrease consecutively for equal quantities of mono‐, di‐, tri‐ and tetra‐butyltin species, but are nearly equal for the first three in the presence of complexing dichromate (Cr 2 O 7 2− ). The lesser signal increase for tetrabutyltin indicates a dissimilar low‐temperature complexation chemistry for the fully ligated neutral organometal to that for the ligated ions. similar results are demonstrated in post‐column addition of a matrix modifier to effluent containing either organotin or organolead species.