Elsevier

Talanta

Volume 219, 1 November 2020, 121316
Talanta

Study of passive sampler calibration (Chemcatcher®) for environmental monitoring of organotin compounds: Matrix effect, concentration levels and laboratory vs in situ calibration

https://doi.org/10.1016/j.talanta.2020.121316Get rights and content

Highlights

  • Calibration method of passive sampler accumulation have an impact on the sampling rate.

  • Aqueous matrix used during calibration has an impact on sampling rate determination.

  • Concentration level set during calibration affect the sampling rate determination.

  • In-situ calibration provides the most relevant sampling rates.

Abstract

Application of Chemcatcher® to monitor organotin compounds [monobutyltin (MBT), dibutyltin (DBT) and tributlytin (TBT)] in sea water has been little developed. Prior to the measurement of the time-weighted average water concentrations (TWAC), a calibration step is required to determine sampling rates (Rs) which is usually assessed in a flow-through laboratory pilot where experimental conditions are well controlled. This paper investigates the effect of the water matrix (tap water vs real sea water from the harbor of Port Camargue in France) and organotin concentrations on the uptake rates of organotin compounds. Laboratory calibrations provided sampling rates in the range of 66–225 mL.day−1 in high concentration (usually used for laboratory calibrations) and in the range of 30–56 mL.day−1 at low concentrations (environmental range). When the tank is filled with real sea water, sampling rates were found to be in the range of 38–177 mL.day−1. In order to demonstrate the efficiency of Chemcatcher® in real conditions, in situ calibration was done in the harbor of Port Camargue. This calibration has been done in order to replicate environmental conditions: compounds concentrations, hydrodynamic and water matrix effects. To compare the impact of calibration procedures on TWAC determination, Chemcatcher® was deployed in the harbor of Port Camargue and spot sampling was performed to monitor the concentrations of organotins in water throughout the exposure period. Results obtained using the field Rs determined by in situ calibration were more reliable. In this case, TWAC is in agreement with spot sampling concentration.

Introduction

The organotin compounds monobutyltin (MBT), dibutyltin (DBT) and tributyltin (TBT) have been known for several years to be amongst the most hazardous compounds for both humans and aquatic ecosystems. This is due to their high toxicity, particularly that of tri-substituted organotins (R3SnX), and above all, tributyltin (TBT). The effects of these compounds in the aquatic environment can be observed at concentrations of less than 1 ng.L−1 [1,2]. Among these effects, the most well documented are the thickening of oyster shells and imposex in gastropods [[3], [4], [5]]. Organotin compounds have teratogenic properties and can cause disruptions to reproductive function in mammals, as well as acting as endocrine disruptors, hepatoxins, immunotoxins, neurotoxins and obeseogens [[6], [7], [8], [9]]. Organotins have been used for years in several activity sectors, but particularly as antifouling paints for boats, namely a biocide to protect the hull. Organotins have been used as stabilizers in PVC, as well as in pesticides and bactericides [[9], [10], [11]]. In 2001, regulations surrounding the use of organotins were put in place, and the use of organotin-based antifouling paints was prohibited by the International Convention on the Control of Harmful Anti-fouling Systems on Ships (AFS Convention Annex 1, 2001) [12]. Organotin compounds are included in the list of priority pollutants of the US Environmental Protection Agency (US-EPA) and the European Commission. In 1999, the US-EPA [13] recommended a maximum of 10 ng.L−1 of TBT (as a cation) in seawater and 63 ng.L−1 in freshwater. Meanwhile the European Environmental Quality Standard (EQS) of TBT for all types of waters covered by WFD (Water Framework Directive) is 0.2 ng.L−1 for annual average concentration, and a maximum allowed concentration of 1.5 ng.L−1 in unfiltered water samples [14]. However, despite these regulations, organotins are still found in the environment due to their stability in sediments. In fact, studies have shown that the half-life of TBT within an aquatic compartment can reach up to more than 10 years, depending on the sediment and water conditions [15]. Measurement of the concentration of these pollutants in the water column is therefore important for assessing their potential long-term biological impact.

As the total concentration of organotin compounds in contaminated water is typically near the ng.L−1 level, it is necessary to use large volumes of water and/or a pre-concentration step during analysis to reach the detection limit. In order to monitor levels of organotin in the aquatic environment, both bio-monitoring (measurement of the accumulation of pollutants in the tissues of living organisms) [16,17] and water sample collection [18] are usually used. However, the latter sampling method measures the concentration of compounds only at the time and point of sampling. This method is unreliable if there are fluctuations within a water compartment over short periods (such as effluent input, tidal cycle). In these cases, it would be necessary to monitor over a longer time period to obtain a time-weighted average water concentration (TWAC) measurement. This information can be obtained using passive sampling devices.

The use of passive sampling techniques as an alternative strategy for monitoring water quality has been gaining interest in recent years [[19], [20], [21], [22]]. Passive sampling devices allow the measurement of compounds in water (and are generally bio-available), and can provide more efficiency in storage, deployment and sensibility. A lot of passive sampling devices are available depending on the pollutant of interest and the matrix sampled. The Polar Organic Chemical Integrative Sampler (POCIS) [[23], [24], [25]] is used to monitor polar (log Kow < 3) hydrophilic organic compounds (pharmaceutical residues, herbicides). The Semi-Permeable Membrane Devices (SPMD) can be used for non-polar (logKow > 3) organic compound sampling such as PAHs, PCBs and pesticides [16,26]. Inorganic compounds such as Cu, Cd, Ni, Pb or Zn can be sampled using Diffusion Gradient Thin films (DGT) [[27], [28], [29]]. This sampler has also been reworked to monitor organic compounds like antibiotics or pesticides for which it has been renamed o-DGT [30,31]. They also have been used for organotin monitoring in coastal sediments [32]. The Chemcatcher® passive sampler device, by contrast, can be deployed to evaluate the time-weighted average concentration (TWAC) of both organic [33,34] and inorganic (heavy metal) compounds [35] in the aquatic environment (1.5 < log(know) < 6). These different types of passive sampling devices allow the monitoring of numerous compounds, however, calibration data such as the sampling rate are not always available. Therefore, field application data are often reported as the amount of pollutant sequestered in the receiving phase, rather than the estimated time-weighted average water concentration (TWAC) obtained with the calibration sampling rate. All passive sampling devices have a receiving phase with a high affinity for the analytes of interest and this phase is separated from the contaminated environment by a diffusion membrane. Contaminants are caught by the receiving phase and accumulated until extraction and analysis. After laboratory calibration of the sampler (using usually a flow-through calibration tank), the TWAC of a pollutant in the water can be calculated thanks to the sampling rate obtained. Passive samplers can be used for short-term (few days) and long-term exposures (several weeks).

However, calibration using the passive sampling method remains controversial. This calibration step is required to calculate a sampling rate value in order to use this sampler as a semi-quantitative tool (Morin et al. 2013; Morin et al. 2012) [36,37]. Various methods of calibration can be used, ranging from laboratory calibration to field calibration. Laboratory calibrations are conducted under controlled conditions (temperature, flow or velocity, pH and salinity of the water matrix, lack of biofouling) including static with negligible depletion [38,39], static with renewal [40], static with partition controlled delivery [41], flow through [33,42] and in artificial streams or channels [43,44]. Only a few studies were done with in situ calibration of passive samplers compared to laboratory calibrations [[45], [46], [47], [48], [49], [50], [51]].

The choice of calibration depends on the passive sampler used and the compounds studied and can impact the sampling rate calculation, and therefore the ambient concentration estimation. Since calibrations are generally performed in the laboratory with tap or synthetic waters spiked with high concentration levels and without significant fouling, laboratory sampling rates could be different than the effective ones in real environmental conditions. Numerous studies using the Chemcatcher® device were performed in a laboratory. Typically, a calibration tank is used to obtain compounds’ sampling rates [52]. Due to the lack of standardization and numerous methods of calibration, different experiments can result in different sampling rates, depending on turbulence, sampler exposure, homogeneity, duration, concentration, etc. [20,33,53]. Another impacting factor is the water matrix used during the calibration process. The compositions, including pH and ionic strength, of tap, sea, river and distilled water are in fact slightly different, and could have an impact on compound sampling. In order to minimize the impact of these differences, two other forms of calibration can be done: in situ calibration, and uptake of PRC (performance and reference compounds). PRC are compounds with the same behavior as analytes that are loaded into the sampler. Monitoring of PRC dissipation from the sampler to the aquatic matrix is then performed to estimate the sampling rate of the targeted contaminant. However, this method is not compatible with all passive samplers and compounds. In fact, the chosen PRC must be able to dissipate from the sampler, which is sometimes difficult to find, particularly for a Chemcatcher® device using C18 disks and POCIS, due to the anisotropic transfer of analytes from the water to the sampler. Furthermore, the dissipation must be fast enough to measure the difference from the beginning of the calibration period to the end. For organotin sampling with Chemcatcher®, for example, the most similar compound is tripropyltin, which is not found in the environment, and is currently used as an internal standard for analytical purposes. But its use as a PRC would contaminate the sampling site and complicate the analysis procedure. As a consequence, for organotin compounds, Chemcatcher® calibrations have only been done in a laboratory with synthetic sea water [20] and no in-situ calibration has been performed with Chemcatcher® devices for organotin monitoring.

The aim of this study was to investigate the effect of the type of Chemcatcher® calibration on the sampling rate of tributyltin (TBT), dibutyltin (DBT) and monobutyltin (MBT) in order to monitor these compounds in harbor areas. Laboratory calibrations were performed to study the influence of the water matrices used in the laboratory pilot, including tap water and real sea water matrices. Then, the influence of concentration levels in the flow-through calibration tank using concentrations closer to environmental levels was also considered. Finally, for the first-time, field calibration was performed in real conditions in an harbor area and compared with laboratory calibration done with water sampled from this harbor.

This study could help to determine the calibration method that is most relevant to the assessment of TWAC in different environmental conditions and the researchers’ aim and monitoring objectives.

Section snippets

Chemicals and reagents

All solvents and reagents were of analytical grade, or higher, purity. Tributyltin chloride (96%), dibutyltin dichloride (97%), and monobutyltin trichloride (95%) were obtained from Sigma-Aldrich Chimie SARL (Saint-Quentin Fallavier, France) and LGC Promochem (Molsheim, France), and the tripropyltin chloride (98%) from Strem Chemicals (Bischeim, France). Tripropyltin was used as a chromatographic internal standard because it is easily derivatized, and normally absent in polluted water. All

Receiving phase disks

C18 Empore™ disks (47 mm diameter) were obtained from Affinisep (Affinisep, France). The disks were pre-conditioned by overnight soaking in methanol, and rinsed several times with ultrapure water. The disks were not allowed to dry out between pre-conditioning and use. They were found to be free of contamination by the organotin compounds tested in this investigation.

Diffusion membranes

Cellulose Acetate (0.45 μm pore size) Whatman™ membranes were from GE Healthcare Life Sciences (Germany). The membranes were

Results and discussion

Uptake rates of organotin compounds in flow-through calibration tank calibration studies.

Conclusion

This study highlights the impact of calibration on the sampling rate of organotin compounds and consequently on TWAC measurements. Environmental concentrations of analytes in the pilot impacted the sampling rate compared to the high concentrations typically used in a laboratory. Further experimentation will be required to elucidate this phenomenon. For example, accumulation factors and kinetics could be quantified to monitor concentration levels during the accumulation period. This work also

Author Contribution

Antoine Garnier. Conceptualization, Methodology, Validation, Investigation, Writing - original draft, Writing - review & editing, Visualization, Catherine Gonzalez. Conceptualization, Methodology, Validation, Writing - review & editing, Visualization, Supervision, Project administration, Funding acquisition. Chrystelle Bancon-Montigny, Conceptualization, Methodology, Validation, Writing - review & editing, Visualization, Supervision, Project administration, Funding acquisition. Sophie Delpoux,

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgements

We acknowledge the financial support of the Occitanie region (80%) and of the École des Mines d’Alès (20%) (ALDOCT-000140) for this work realized in collaboration with the Laboratoire de Génie de l’Environnement Industriel of Alès (LGEI) and HydroSciences Montpellier (HSM).

References (59)

  • C.E. Chen et al.

    In situ measurement of solution concentrations and fluxes of sulfonamides and trimethoprim antibiotics in soils using o-DGT

    Talanta

    (2015)
  • R.F. Cole et al.

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

    Talanta

    (2018)
  • B. Vrana et al.

    Calibration of the Chemcatcher passive sampler for the monitoring of priority organic pollutants in water

    Environ. Pollut.

    (2006)
  • N. Morin et al.

    Chemical calibration, performance, validation and applications of the polar organic chemical integrative sampler (POCIS) in aquatic environments

    Trac. Trends Anal. Chem.

    (2012)
  • N. Morin et al.

    Determination of uptake kinetics and sampling rates for 56 organic micropollutants using "pharmaceutical" POCIS

    Talanta

    (2013)
  • M. Shaw et al.

    Uptake and release of polar compounds in SDB-RPS Empore disks; implications for their use as passive samplers

    Chemosphere

    (2009)
  • D. O'Brien et al.

    Determination of deployment specific chemical uptake rates for SDB-RPD Empore disk using a passive flow monitor (PFM)

    Chemosphere

    (2011)
  • R. Jacquet et al.

    Comparison of five integrative samplers in laboratory for the monitoring of indicator and dioxin-like polychlorinated biphenyls in water

    Chemosphere

    (2014)
  • J. Camilleri et al.

    Determination of the uptake and release rates of multifamilies of endocrine disruptor compounds on the polar C18 Chemcatcher. Three potential performance reference compounds to monitor polar pollutants in surface water by integrative sampling

    J. Chromatogr. A

    (2012)
  • R.B. Schafer et al.

    Performance of the Chemcatcher passive sampler when used to monitor 10 polar and semi-polar pesticides in 16 Central European streams, and comparison with two other sampling methods

    Water Res.

    (2008)
  • S. Aguerre et al.

    Physico-chemical approach to study organotin sorption–desorption during solid-phase microextraction

    J. Chromatogr. A

    (2003)
  • C. Moschet et al.

    Evaluation of in-situ calibration of Chemcatcher passive samplers for 322 micropollutants in agricultural and urban affected rivers

    Water Res.

    (2015)
  • Z. Zhang et al.

    Analysis of emerging contaminants in sewage effluent and river water: comparison between spot and passive sampling

    Anal. Chim. Acta

    (2008)
  • I. Ibrahim et al.

    In-situ calibration of POCIS for the sampling of polar pesticides and metabolites in surface water

    Talanta

    (2013)
  • S. Lissalde et al.

    Overview of the Chemcatcher® for the passive sampling of various pollutants in aquatic environments Part B: field handling and environmental applications for the monitoring of pollutants and their biological effects

    Talanta

    (2016)
  • A. de la Cal et al.

    Evaluation of the aquatic passive sampler Chemcatcher for the monitoring of highly hydrophobic compounds in water

    Talanta

    (2008)
  • N. Briant et al.

    Behaviour of butyltin compounds in the sediment pore waters of a contaminated marina (Port Camargue, South of France)

    Chemosphere

    (2016)
  • C. Bancon-Montigny et al.

    Optimisation of the storage of natural freshwaters before organotin speciation

    Water Res.

    (2001)
  • G. Poulier et al.

    Can POCIS be used in Water Framework Directive (2000/60/EC) monitoring networks? A study focusing on pesticides in a French agricultural watershed

    Sci. Total Environ.

    (2014)
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