What are Organotins and why are they of environmental concern?

Organotins are compounds with at least one tin atom covalently bound to a hydrocarbon. They are widely used in industry and agriculture as they possess antifungal and antibacterial properties. They are essential in antifouling paints, wood preservatives, and as stabilisers and catalysts in plastics, notably PVC production.

Among these, Tributyltinoxide (TBTO) gained attention, as it was used in antifouling paints to deter marine organism growth on ships and marine structures but breaks down into persistent and ecotoxic Tributyltin (TBT), harming aquatic life and posing health risks. Many nations, led by the International Maritime Organization, banned, or restricted TBTO use since 2008, reducing TBT contamination significantly. Ongoing monitoring is vital to safeguard wildlife from any residual TBT impacts especially in ports and harbours.

Image 1: Organotins are used in the production of antifouling paints, wood preservatives and plastics production including PVC.

How do we analyse Organotins at Eurofins Environment Testing?

As there are multiple organotin compounds that can be found in the environment with each exhibiting varying levels of toxicity. It is very important to speciate these to assess their individual impact within the analysed sample accurately.

A rapid method for the speciation of Organotins has been developed, deploying Liquid Chromatography with Inductively Coupled Plasma Mass Spectrometry (LC-ICP-MS). This technique offers exceptional sensitivity, specificity, and selectivity, eliminating the need for an additional derivatisation step.

Our approach allows for the quantitative determination of Monobutyltin (MBT), Dibutyltin (DBT), and Tributyltin (TBT) in aqueous (drinking water, surface water, saline water, wastewater, leachates) and solid (soil, sediment, biosolids) samples. Our method is ISO17025 accredited, and the Limits of Reporting (LORs) are according to the relevant guidelines. The advantage of this instrument setup is that it can also be adapted for the speciation of arsenic and chromium.

Image 2: A rapid method for the speciation of Organotins has been developed utilising LC-ICP-MS.

How do we report our results?

For comparison of the obtained results with the regulatory limits of the relevant Guidelines in Australia and Aotearoa New Zealand (see Table below), the TBT results are stoichiometrically converted into the correct format TBTO and Tributyltin (as Sn) using the factors outlined in Figure 3.

Figure 3: Conversion factors of measured results to TBTO and TBT as Sn