Species-Specific Isotope Dilution Analysis and Isotope Pattern Deconvolution for Butyltin Compounds Metabolism Investigations

Abstract

A methodology for the study of the absorption and metabolism of butyltin compounds in laboratory animals using isotopically enriched species was developed. The method is based on the oral administration of 119Sn-labeled monobutyltin (MBT), 118Sn-labeled dibutyltin (DBT), and 117Sn-labeled tributyltin (TBT) to the animals and the measurement of both the concentration and isotopic composition of these compounds in the different tissues by GC-ICPMS. The degradation of butyltin compounds during their metabolism was computed using least-squares isotope pattern deconvolution, and their concentration was measured by reverse isotope dilution analysis using natural-abundance MBT, DBT, and TBT standards. Male Wistar rats were used as models to evaluate the proposed methodology. Preliminary toxicological results obtained with one rat indicate that TBT is highly absorbed (64.4%), and it is found in all organs with relatively high levels in stomach and intestines. The apparent absorption of DBT was 27.3% and was mainly found in liver, kidney, and intestines. However, a large proportion of the found DBT is formed from the degradation of TBT (approximately 40% of the found DBT in liver is degraded TBT). The apparent absorption of MBT was found to be 12.5%, and the originally administered MBT was mainly recovered in the feces. However, MBT was clearly detected in liver, kidney, stomach, intestines, and urine as degradation products of DBT and TBT. Although a significant variability from rat to rat is expected to be obtained, the analytical variability provided by this methodology is small enough to yield meaningful biological results. The results obtained demonstrate that the developed methodology is able to follow qualitatively, quantitatively, and simultaneously the specific metabolic pathways of different species of a given element.

Absorption, distribution, metabolism and excretion of selenium following oral administration of elemental selenium nanoparticles or selenite in rats

“…Quantification was carried out using post-column isotope dilution using an enriched (99.2%) 77 Se standard. 24 The enriched isotope (10 ng Se per mL using mobile phase A as solvent) was pumped using a peristaltic pump and its accurate flow was monitored daily by weighing. The enriched stable isotope and the eluent from the HPLC column were mixed via a T-piece before entry into the nebulizer of the ICP-DRC-MS, which was used to detect the spike isotope ( Diagnostics, Oslo, Norway) with a reference value for Se of 58.6 ng Se per mL was used.…”

Fate and tidal transport of butyltin and mercury compounds in the waters of the tropical Bach Dang Estuary (Haiphong, Vietnam)

“…The isotopically enriched species were spiked and left to equilibrate for 15 min. The extraction conditions were 75°C (mercury analysis) or 70°C (tin analysis) for 4 min with stirring (Rodríguez-González et al, 2005;Rodríguez Martín-Doimeadios et al, 2003).…”

“…Detailed information on the organomercury and organotin species determination can be found elsewhere (Monperrus et al, 2005b;Rodríguez-González et al, 2005;Rodrí-guez Martín-Doimeadios et al, 2003).…”

Paradigms in isotope dilution mass spectrometry for elemental speciation analysis

“…The relationship between the obtained slopes and unknown physical parameters, is explained in more detail elsewhere [9]. The inter-conversion coefficients˛andˇ, for example, can be obtained by solving these two equations: Needless to say that isotope pattern deconvolution method can be applied to other, more complicated, systems, such as the quantitation of mono-, di-, and tributyltin species using triple spiking IDMS [69]. It is important to stress that the attractiveness of multiple spiking isotope dilution stems from the fact that it is possible to identify and correct for species inter-conversion in a single measurement.…”