Development and evaluation of a new diffusive gradients in thin-films technique for measuring organotin compounds in coastal sediment pore water

Abstract

Organotins present a toxicological risk to biota in the aquatic environment. Understanding the behaviour of these compounds in sediment is challenging, with sophisticated analytical techniques required for their measurement. We investigated the use of silica-bound sorbents for diffusive gradients in thin-films (DGT) adsorption gels to pre-concentrate five organotins (monobutlytin (MBT), dibutyltin (DBT), tributyltin (TBT), diphenyltin (DPhT), triphenyltin (TPhT)) found frequently in coastal sediment. C sorbent showed optimum performance in uptake and recovery of organotins for pH and ionic strength ranges typical of coastal waters. Recoveries from adsorption gels deployed in filtered sea water were MBT = 123 ± 20%, DBT = 75 ± 12%, TBT = 81 ± 16%, DPhT = 72 ± 30%, TPhT = 58 ± 10% respectively. Devices were used to investigate DGT fluxes and pore water concentrations of organotins in coastal sediment collected from a contaminated site. DGT fluxes measured in sediment cores for the five organotins ranged between 4.3 × 10 and 1.6 ×10ngcms. The depletion of organotin species within pore waters at the interface with DGT devices was measured over a series of deployment times (2, 7, 14, 21 and 28 days) and provided estimates of the concentration of organotins in pore waters at Langstone Harbour, UK, prior to depletion by the DGT device and information on their spatial heterogeneity. The novel in situ DGT device developed can pre-concentrate organotins from pore waters in coastal sediment core samples and allows their detection at low environmental concentrations using conventional gas chromatographic/mass spectrometric instrumentation. Use of the DGT device overcomes many problems associated with the conventional pore water sampling of organotins. Our preliminary data suggests it has potential in the future to be a useful tool in investigating the environmental fate of these pollutants. The use of the C gel will also allow for the simultaneous sequestration of other semi- and non-polar analytes present in the pore water.

Diffusive gradients in thin films: devices, materials and applications

“…Fernandez-Gomez et al (2015) measured and predicted the concentration and bioavailability of MeHg in water using thiol-functionalized resin gel DGT, confirming the DOM can enhance the MeHg photodegradation process. DGT based on silica-bound sorbents was successfully employed for the measurement of five organotin compounds in sediments (Cole et al 2018). The obtained 1D profile distributions demonstrated spatial distribution heterogeneity for five organotin compounds, with DGT fluxes ranging between 4.3 × 10 −8 and 1.6 × 10 −5 ng cm 2 s −1 in sediments.…”

“…The application of hydrophilic-lipophilic-balanced (HLB) binding agents has been reported for the measurement of household and personal care products (HPCPs) in waters, being effective in the pH range of 3.5-9.5, and ionic strengths of 0.001-0.1 M, with dissolved organic matter levels of 0-20 mg L −1 (Chen et al 2017b). Chen et al (2018c) further compared the performances of three different resins [HLB, XAD18 and Strata-XL-A (SXLA)] for measuring endocrine disrupting chemicals, showing that the measurements with HLB and XAD18 DGT were more stable than that of SXLA-DGT, with the tolerant pH range of 3.5-9.5 and ionic strength of 0.001-0.5 M. The use of DGT for measurement of organometallics have been optimized, with Cole et al (2018) using Bondesil ® C 8 silica particles as DGT sorbents for measurement of five organotin compounds in sediment, with performances effective within a range of pH 4-9 and ionic strength of 0.01-1 M NaCl.…”

Monitoring and Modelling of Butyltin Compounds in Finnish Inland Lake

“…Estimation of the sources and transport of BTC's and especially TBT is difficult due to their low aquatic concentrations. BTCs are highly attracted by solid particles or bioaccumulated and commonly determined in sediment samples or aquatic organisms (Page et al 1996, Berto et al 2007, Cole et al 2018. They also have long transformation chain from tertbutyltin (TeBT) to MBT (TeBT→TBT→DBT→MBT).…”

Investigating Potential Limitations of Current Diffusive Gradients in Thin Films (DGT) Samplers for Measuring Organic Chemicals

“…In contrast, research and development of DGT for organic chemicals only started in 2012, but it has already attracted considerable interest and is developing rapidly . To date, sampler development and testing of 136 organic compounds has been reported in the literature (a few from personal communication), with more being conducted. − Compound classes include pharmaceuticals and personal care products, illicit drugs, endocrine-disrupting chemicals and pesticides, etc. Table S1 summarizes these publications.…”