Calibration and use of the Chemcatcher passive sampler for monitoring organotin compounds in water

An integrative passive sampler (Chemcatcher^®) consisting of a 47 mm C₁₈ Empore™ disk as the receiving phase overlaid with a thin cellulose acetate diffusion membrane was developed and calibrated for the measurement of time-weighted average water concentrations of organotin compounds [monobutyltin (MBT), dibutyltin (DBT), tributlytin (TBT) and triphenyltin (TPhT)] in water. The effect of water temperature and turbulence on the uptake rate of these analytes was evaluated in the laboratory using a flow-through tank. Uptake was linear over a 14-day period being in the range: MBT (3-23 mL day⁻¹), DBT (40-200 mL day⁻¹), TBT (30-200 mL day⁻¹) and TPhT (30-190 mL day⁻¹) for all the different conditions tested. These sampling rates were high enough to permit the use of the Chemcatcher^® to monitor levels of organotin compounds typically found in polluted aquatic environments. Using gas chromatography (GC) with either ICP-MS or flame photometric detection, limits of detection for the device (14-day deployment) for the different organotin compounds in water were in the range of 0.2-7.5 ng L⁻¹, and once accumulated in the receiving phase the compounds were stable over prolonged periods. Due to anisotropic exchange kinetics, performance reference compounds could not be used with this passive sampling system to compensate for changes in sampling rate due to variations in water temperature, turbulence and biofouling of the surface of the diffusion membrane during field deployments. The performance of the Chemcatcher^® was evaluated alongside spot water sampling in Alicante Habour, Spain which is known to contain elevated levels of organotin compounds. The samplers provided time-weighted average concentrations of the bioavailable fractions of the tin compounds where environmental concentrations fluctuated markedly in time.     

Application of Chemcatcher passive sampler for monitoring levels of mercury in contaminated river water

A passive sampler (Chemcatcher) consisting of a 47 mm Empore™ chelating disk (CHE) with iminodiacetic groups as the receiving phase overlaid with a diffusion membrane was developed and calibrated for the monitoring of Hg in water. Three different diffusion membranes including cellulose acetate (CA), polyethersulphone (PS) and cellulose dialysis membrane (D) were tested. The best performance was obtained with the CHE-PS tandem. The effective sampling rate of the device (R_s, L day⁻¹) is defined as the equivalent volume of water extracted per unit time, and is analyte specific and can be determined experimentally in a flow-through tank. Effects of water temperature and turbulence on the uptake rate of Hg were assessed under controlled laboratory conditions. Sampling rates were in the range of 0.029-0.091 L day⁻¹. An increase in sampling rate with turbulence was demonstrated. The detection limit of the sampler obtained in flowing waters ranged between 2.2 and 2.9 ng L⁻¹ Hg. The performance of Chemcatcher was tested alongside spot water sampling in a 14-day field deployment at two locations on the Valdeazogues River, Almadén, Spain. In general, the Hg concentration estimated by the Chemcatcher was lower than that found in spot water samples collected over the same period. This may be explained by the behaviour of this sampler that measures only the labile fraction of Hg in water, and this will exclude some species. However, Chemcatcher preconcentrates Hg allowing its determination in some places where its concentration is below the detection limit of spot sampling.     

Mercury and organotin compounds monitoring in fresh and marine waters across Europe by Chemcatcher passive sampler

Several field trials have been carried out to assess the performance of the passive sampler Chemcatcher as aquatic monitoring technology for inorganic mercury and the organotin pollutants monobutyltin (MBT), dibutyltin (DBT) and tributyltin (TBT) in different types of waters across ten locations in Europe. Two version of the sampler were used. One for mercury that consists on 47?mm Empore? disks of iminodiacetic chelating groups as the receiving phase overlaid by a diffusion membrane of polyethersulphone; and other for organotin compounds comprising a C₁₈ disk and a cellulose acetate membrane. Both membranes were held in a disposable polycarbonate body. The two samplers were calibrated in the laboratory in a previous work to estimate the pollutant concentration. For field sampling, the samplers were deployed for 14 days. In parallel spot samples were periodically collected during the deployment period for comparison purposes. No significant biofouling on the samplers was observed for the locations monitored. In general, water concentrations estimated by Chemcatcher were lower than those found in spot water samples due to the device only collected the soluble bioavailable fraction of target pollutants. However, the pre-concentration capability of Chemcatcher allowed the determination of the tested pollutants at levels where spot sampling fails, even in difficult water bodies such as sewage treatment plants. These advantages lead to consider this emerging methodology as a complementary tool to traditional spot sampling.     

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

The Chemcatcher passive sampler was primarily developed for the detection and quantification of priority organic pollutants (e.g., polycyclic aromatic hydrocarbons) in water. In the present study, this prototype was evaluated for highly hydrophobic compounds such as the tetrabrominated diphenyl ether BDE-47, the hexabrominated diphenyl ether BDE-153, and the historic pesticide DDT with its main metabolites (DDE and DDD). The sampling device consists basically of a receiving phase with high affinity for organic chemicals which is separated from the environment by a diffusion limiting membrane, both placed in a rigid PTFE body. C18 Empore disks were evaluated as receiving phase, obtaining a better accumulation when impregnated until saturation with n-octanol. As diffusion membrane, low density polyethylene was chosen over polyethersulphone. Once optimized its accumulation capacity for the target compounds, the linear behaviour of this accumulation was investigated and shown to be satisfactory in a period of 15 days. Preliminary uptake rates calculated from that accumulation anticipate the utility of this device for the detection of DDXs and the PBDEs, as calculated limits of detection are lower than usually reported environmental concentrations.     

A new application of imprinted polymers: Speciation of organotin compounds

Molecular imprinting technology has been employed for the first time to prepare a specifically affinity chromatographic stationary phase for speciation purposes. Tributyltin has been chosen as the template molecule and the non-covalent approach has been applied. Three different polymerization methods have been evaluated: (i) a composite material, (ii) a polymer prepared via-Iniferter grafting; (iii) an emulsion polymer. Columns packed with different polymers have been evaluated by liquid chromatography (LC) coupled to inductively coupled plasma mass spectrometry (ICP-MS). The chromatographic conditions as well as the analytical characteristics of the developed method are discussed in this paper. Our findings have shown formation of specific cavities in the grafted Iniferter as well as in the emulsion polymers with the latter achieving resolution of four organotin compounds. Detection limits are similar to those obtained with commercial, but not specific, stationary phases (6 pg for monobutyltin, MBT; 10 pg for both tributyltin, TBT, and triphenyltin, TPhT; and 20 pg for dibutyltin, DBT). The main advantage of this proposed stationary phase is that good recovery is obtained for all species, including MBT. Baseline resolution for TBT and TPhT has also been obtained. The high selectivity of this column prevents matrix interferences. The method has been validated by analyzing two biota reference materials (ERM-CE477 mussel tissue and T-38 oyster tissue).     

Strategies for monitoring the emerging polar organic contaminants in water with emphasis on integrative passive sampling

Although polar organic contaminants (POCs) such as pharmaceuticals are considered as some of today's most emerging contaminants few of them are regulated or included in on-going monitoring programs. However, the growing concern among the public and researchers together with the new legislature within the European Union, the registration, evaluation and authorisation of chemicals (REACH) system will increase the future need of simple, low cost strategies for monitoring and risk assessment of POCs in aquatic environments. In this article, we overview the advantages and shortcomings of traditional and novel sampling techniques available for monitoring the emerging POCs in water. The benefits and drawbacks of using active and biological sampling were discussed and the principles of organic passive samplers (PS) presented. A detailed overview of type of polar organic PS available, and their classes of target compounds and field of applications were given, and the considerations involved in using them such as environmental effects and quality control were discussed. The usefulness of biological sampling of POCs in water was found to be limited. Polar organic PS was considered to be the only available, but nevertheless, an efficient alternative to active water sampling due to its simplicity, low cost, no need of power supply or maintenance, and the ability of collecting time-integrative samples with one sample collection. However, the polar organic PS need to be further developed before they can be used as standard in water quality monitoring programs.     

A novel approach for monitoring of cyanobacterial toxins: development and evaluation of the passive sampler for microcystins

We have investigated the ability of an integrative sampler for polar organic chemicals to sequestrate a group of common and highly hazardous cyanobacterial toxins—microcystins. In a pilot experiment, commercially available passive samplers were shown to effectively accumulate microcystins after 7 days’ exposure in the field. To find the most efficient configuration for sequestration of microcystins, four different porous membranes (polycarbonate, polyester, polyethersulfone and nylon) and two sorbents (Oasis HLB and Bondesil-LMS) were evaluated in the laboratory experiments, where samplers of different configuration were exposed to microcystins (microcystin-RR and microcystin-LR) for 14 days under steady conditions. We observed differences in sampling rates and amounts of accumulated microcystins depending on the sampler configurations. The samplers constructed with the polycarbonate membrane and Oasis HLB sorbent (2.75 mg/cm²) provided the highest sampling rates (0.022 L/day for microcystin-RR and 0.017 L/day for microcystin-LR). To the best of our knowledge, the present study is the first reporting application of passive samplers for microcystins, and our results demonstrate the suitability of this tool for monitoring cyanotoxins in water.     

Development of a new passive sampler based on diffusive milligel beads for copper analysis in water

A new passive sampler was designed and characterized for the determination of free copper ion (Cu²⁺) concentration in aqueous solution. Each sampling device was composed of a set of about 30 diffusive milligel (DMG) beads. Milligel beads with incorporated cation exchange resin (Chelex) particles were synthetized using an adapted droplet-based millifluidic process. Beads were assumed to be prolate spheroids, with a diameter of 1.6 mm and an anisotropic factor of 1.4. The milligel was controlled in chemical composition of hydrogel (monomer, cross-linker, initiator and Chelex concentration) and characterized in pore size. Two types of sampling devices were developed containing 7.5% and 15% of Chelex, respectively, and 6 nm pore size. The kinetic curves obtained demonstrated the accumulation of copper in the DMG according to the process described in the literature as absorption (and/or adsorption) and release following the Fick's first law of diffusion. For their use in water monitoring, the typical physico-chemical characteristics of the samplers, i.e. the mass-transfer coefficient (k₀) and the sampler-water partition coefficient (K_sw), were determined based on a static exposure design. In order to determine the copper concentration in the samplers after their exposure, a method using DMG bead digestion combined to Inductively Coupled Plasma – Atomic Emission Spectrometry (ICP-AES) analysis was developed and optimized. The DMG devices proved to be capable to absorb free copper ions from an aqueous solution, which could be accurately quantified with a mean recovery of 99% and a repeatability of 7% (mean relative uncertainty).     

Trends in the use of passive sampling for monitoring polar pesticides in water

The presence of polar pesticides in environmental waters is a growing problem. After application their migration into the aqueous phase is promoted by their high water solubility. Transport processes are usually complex and inputs are generally stochastic; this makes monitoring of this class of pesticides challenging using low volume spot samples of water. Recently there has been a trend to use passive samplers to monitor pesticides in river catchments as it is an in-situ time integrative sampling technique. The three main types of device used for this purpose are, Chemcatcher®, POCIS and o-DGT. This article reviews the fate and current state-of-the-art for monitoring polar pesticides in aqueous matrices. Principles and the theory of passive sampling and strategies for passive sampler design and operation are presented. Advances in the application of passive sampling devices for measuring polar pesticides are extensively critiqued; future trends in their use are also discussed.     

Encapsulation of organotin compounds in metal acetate glasses

Triorganotin halides, oxides and sulphides can be dissolved in molten, mixed-metal acetates at ca 140–160°C without decomposition; quenching provides glasses into which are encapsulated the organotin species. Halide/acetate and oxide/acetate, but not sulphide/acetate, exchanges occur in the melt. Only partial exchange was found for hindered trineophyl tin chloride [(PhCMe₂CH₂)₃SnCl], in contrast to the complete exchanges observed for the butyl (Bu), phenyl (Ph) and cyclohexyl (Cy) analogues. Complete oxide/acetate exchange was found for (Bu₃Sn)₂O, partial exchange occurred for (Cy₃Sn)₂O, whilst no exchange resulted with bis(trineophyltin) oxide or (Ph₃Sn)₂O. Tin–tin bonds (e.g. as in Ph₃SnSnPh₃) and carbon–tin bonds (even the allyl–Sn bond in Bu₃SnCH₂CH?CH₂) are not affected. The acetate glasses dissolve in aqueous media with release of the organotin species and they have potential as slow-release systems which is currently being investigated.     

Improving detection limits for organotin compounds in several matrix water samples by derivatization-headspace-solid-phase microextraction and GC-MS

Triethyltin, tributyltin, diphenyltin and triphenyltin were selected as model compounds. The method is based on in situ ethylation and simultaneous headspace-solid-phase microextraction (HS-SPME) and gas chromatographic-mass spectrometry analysis (GC-MS). The extraction procedure was optimized studying some variables such as reaction time, salinity, sample volume and headspace volume. SPME-GC-MS and SPME-GC-FID techniques were compared; quality assurance parameters such as sensitivity, selectivity and precision were established. The proposed procedure showed limits of detection between 0.025 and 1 ng/L. The linearity was in the 0.025-5000 ng/L range. The precision expressed as relative standard deviations (RSD), were below 20%. Real wastewaters and seawaters were analyzed. The method permits controlling legislated annual average values.     

Evaluation of two aquatic passive sampling configurations for their suitability in the analysis of estrogens in water

The presence of estrogens in the aquatic environment has been the target of several studies in the last decade. Newly developed passive sampling techniques for polar organic chemicals show great promise for the assessment of long-time exposure of aquatic organisms to emerging contaminants. In the present work, two configurations of the Chemcatcher^® passive sampler have been tested for their applicability to the analysis of seven estrogens in water. Accumulation experiments in the laboratory, to calculate the uptake rates, and a field trial show that the polar configuration of this device may be used for the efficient sampling and determination of estrogens in water. Time weighted average concentrations were determined in the field trial and compared with spot sampling concentrations. The detection of estriol using passive sampling, although not found with spot sampling, clearly demonstrates the value of this technique in assessing relevant concentrations of estrogens in the aquatic media.     

A passive sampling-based analytical strategy for the determination of volatile organic compounds in the air of working areas

An analytical methodology based on the use of a polyethylene layflat tube filled with activated carbon and Florisil (ACFL-VERAM) was employed for the passive sampling of volatile organic compounds (VOCs) in the air of working areas of packing industries. VOCs amount in the ACFL-VERAM sampler was directly determined through head-space-gas chromatography-mass spectrometry (HS-GC-MS) allowing a direct determination in only 20 min without the need of any previous treatment. Uptake parameters, like sampling rate (R_S) and sampler-air partition coefficient (K_SA), were determined for every studied VOC from adsorption isotherm data. Additionally, experimental equations have been proposed to predict R_S and K_SA from the octanol-air partition coefficients reported in the literature. The proposed methodology reaches method detection levels from 0.007 to 0.2 mg m⁻³ for the studied VOCs.     

A novel mode of access to polyfunctional organotin compounds and their reactivity in Stille cross-coupling reaction

Mono-, di-, tri- and tetra-functional organotin compounds were easily prepared in a sonicated Barbier reaction using ultrasound technology via coupling reaction of organo halides with tin halides (Bu₃SnCl, Bu₂SnCl₂, BuSnCl₃, SnCl₄) mediated by magnesium metal. The di- and tri-functional organotin compounds were tested in a Stille cross-coupling reaction in order to ascertain how many groups were transferred.     

Synthesis and evaluation of molecularly imprinted polymers for organotin compounds: a screening method for tributyltin detection in seawater

The environmental impact of some organotin compounds (OTC) has given particulate importance to analytical studies. This paper reports the first attempt to apply the emerging molecular imprinting technology to this field. Several imprinted polymers have been synthesised by the non-covalent free radical approach using sodium methacrylate (NaMA) or 4-vinylpyridine (4-VP) as monomers in the presence of TBT as template molecule in three different polymerisation media (toluene, acetonitrile and methanol/water). The ability of the polymers synthesised to retain and distinguish TBT from its degradation products has been evaluated and optimized. The results clearly showed the presence of cavities within the polymeric matrix allowing specific recognition of TBT. Cross-reactivity from other Sn species (monobutyltin (MBT), dibutyltin (DBT) and inorganic Sn) has also been evaluated. Rapid and direct differentiation of TBT from its main degradation products in seawater was achieved. The analytical characteristics included linearity (0.05-50 μg l⁻¹), a pre-concentration factor of 150, and a quantification limit of 0.04 μg l⁻¹ for 1 l.     

Relationship of cytotoxic groups in organotin molecules and the effectiveness of the compounds against leukemia

Cytotoxicity of organotin compounds is assessed and their effectiveness against leukemia is discussed. The functional groups attached to the tin atom in organotin compounds control the cytotoxicity of the compound towards the thymus gland. The four organotin moieties which have the greatest toxic effect upon the thymus gland are the tri-n-butyltin, di-n-butyltin, tri-n-propyltin and di-n-octyltin groups. Compounds containing these groups also exhibit the poorest test-control ratio (T/C) values when tested as anti-cancer agents against leukemic mice using NCI protocol.     

Evaluation of desulfurization procedures for the elimination of sulfur interferences in the organotin analysis of sediments

Different clean-up and desulfurization procedures were compared in order to check their efficiency in eliminating elemental sulfur and organosulfur compounds from sediment extracts. Adsorption column chromatography cannot remove elemental sulfur or organosulfur compounds. Treatment with activated copper powder only removes elemental sulfur, but organosulfur compounds remain in the extract, and phenyltins are partially lost (up to 50%). Ligand exchange chromatography with AgNO₃-coated silica gel as adsorbent effectively removes elemental sulfur and interfering organosulfur compounds from the sediment extract allowing the quantitation of butyltins with recoveries >80%. Since the phenyltin compounds do not survive the desulfurization step, they should be measured in the untreated extract.     

Application of passive sampling devices for screening of micro-pollutants in marine aquaculture using LC-MS/MS

Knowledge on the presence of micro-pollutants, in particular emerging contaminants, such as pharmaceuticals, biocides or some pesticides, in semi-enclosed coastal areas, where fish farms are installed, is very limited. This article shows data on the presence of micro-pollutants over 1 year monitoring campaign carried out in a fish farm placed on the Mediterranean Sea. With this work, the results of the development of an analytical procedure which, makes use of passive sampling techniques (with polar organic chemical integrative samplers, POCIS, pharmaceutical configuration) and of the LC-QLIT-MS system, are presented. The development of the analytical procedure entail laboratory-based calibration with the samplers POCIS, for calculating uptake rates and sampling rates of compounds representative of a wide range of polarity (4.56 ≥ log K_ow ≥ −0.12). The uptake of the target compounds in the sampler POCIS, follows a linear pattern for most compounds, and sampling rates varied from 0.001 to 0.319 l/d. The calibration experiments have shown that POCIS pharmaceutical configuration could be used for sampling other non-target compounds, such as pesticides and biocides with a log K_ow ≤ 4. The sampling rates for each selected compound were obtained using spiked seawater for further estimation of time-weighted average (TWA) concentration of micro-pollutants in the water column, during the field study. An analytical method was developed with the LC-QLIT-MS system and validated to ensure a satisfactory performance for the detection of the target micro-pollutants in water. The limits of detection (LODs) achieved were between 0.01 and 1.50 μg/l. During the monitoring campaign, among the selected compounds, metronidazole, erythromycin, simazine, atrazine, diuron, terbutryn, irgarol, trimethoprim, carbaryl, flumequine, TCMTB and diphenyl sulphone (DPS) were detected. Most of target compounds found were at average concentrations which ranged from 0.01 to 75 ng/l. Irgarol, simazine, diuron, atrazine and DPS were the micro-pollutants most frequently detected over the period of the monitoring programme carried out.     

Speciation and GC retention indices of some organotin compounds in water

Analytical methods have been developed for the quantitative determination of Bu₄Sn, Bu₃Sn⁺, Bu₂Sn²⁺, BuSn³⁺, Me₃BuSn, Me₂Bu₂Sn, MeBu₃Sn, MeBuSn²⁺, Me₂BuSn⁺ and MeBu₂Sn⁺ in water. Organotin compounds are extracted from water with tropolone at 0.1 % in n-pentane, derivatized with n-pentylmagnesium bromide and determined by gas chromatography with flame photometric detection or flame ionization detection. Absolute detection limits are 0.05-0.12 ng and 1.2-13 ng as tin, respectively. The method was applied to the analysis of spiked tap-water containing 0.3-1000 ng cm^?3 of each of the organotin compounds.