Versatility of the Chemcatcher®passive sampler device

Adil Bakir a, Gary Fones a and Graham Mills b

aSchool of Earth and Environmental Sciences, University of Portsmouth

b School of Pharmacy and Biomedical Sciences, University of Portsmouth

Why the need for passive samplers

• Monitoring the concentration of chemicals in water is statutory requirement acrossEurope e.g. Water Framework Directive (WFD) (Council Directive 2000/60/EC –2000)

• Within the WFD, Environmental Quality Standards or EQSs are used forassessing the state of the water environment through classification, and are used asthe fundamental measurement in the water quality monitoring programmes.

• EQSs tell us the quantity of a chemical pollutant that can “safely” be present in thewater body without causing harm to the ecology and ideally that presents nosignificant risk to human health.

• National environment agencies in Europe have a legal obligation to ensure that thestatutory EQSs are being met.

• EQS are defined as both the maximum and average permissible concentration of apotentially hazardous chemical in an environmental sample (usually in terms of μgL-1, ng L-1 or pg L-1).

Chemcatcher® - Visual Perspective – Tributyltin EQS

For tributyltin EQS of 0.2 ng L-1

1 drop (20 μL) in 20x Olympic sizedswimming pools

For cypermethrin EQS of 0.008 ng L-1

Analytical challenges

Why the need for passive samplers

• Most monitoring programmes involve the periodic collection of low volume spot samplesof water (bottle or grab) that are analysed subsequently in the laboratory

• Passive samplers can effectively concentrate pollutants compared to spot sampling –lower analytical detection limits

• Passive samplers can provide time-weighted-average (TWA) and equilibriumconcentrations over the deployment time, rather than a snap shot at one moment

Use of passive samplers (cont.)

Chemcatcher® - a cost effective passive sampler

Chemcatcher® – University of Portsmouth

UoP Chemcatcher’s website and on-line store

http://www.port.ac.uk/research/chemcatcher/

UoP Chemcatcher’s website and on-line store

http://www.port.ac.uk/research/chemcatcher/

Chemcatcher® – University of Portsmouth

Chemcatcher® passive sampler

Chemcatcher® – University of Portsmouth

The use of commerciallyavailable solid receivingdisks allows betterhomogeneity of thesorbent material andbetter reproducibilitybetween analysis.

National and International Impact

National and International Impact

National and International Impact

South West Water, NRW and the University ofPortsmouth for its use of the ‘Chemcatcher’passive sampler, in combination with an anionexchange receiving disc, to monitor acidherbicides in river catchments.

Chemcatcher® – Qualitative assessment

• “Screening” mode for the presence or absence of compounds

• Usually used as a “detective work” to pinpoint sources of pollution

• “Upstream thinking” initiative (South West Water) to improve water quality in rivercatchments in order to reduce water treatment costs.

Chemcatcher® – Semi-quantitative and quantitative assessment

• Also can be used as a “detective work” to pinpoint sources of pollution

• Allows quantification of target compounds

• Requires calibration of the Chemcatcher® under laboratory conditions:

Laboratory set-up of the passive samplers on the carousel

Calibration of a passive sampler in a typical flow-through system

Peristaltic pump30 ml/min

Peristaltic pump100 L/min Exposure tank

Water

wastewater

Stirrer

Chemicalsin MeOH

Waterreservoir

overhead stirrer

Samplers

AnalytesIn MeOH

Other designs of system are BATCH (very simple approach) and SEMI-BATCH

Passive sampler uptake profile

Sampling Rate (Rs) derivedfrom this gradient.

Passive sampler uptake profile

Sampling rate RS [L day-1] – equivalent volume of water cleared of the targetanalyte per unit of time

Time weighted average concentration

Time weighted average (TWA) concentrations (CW in ng L-1) can bederived from a simple equation:

where: MS = mass of pollutant on Chemcatcher disk (ng)

M0 = mass of pollutant on field blank Chemcatcher disk (ng)

RS = sampling rate of pollutant (L day-1)

t = Chemcatcher deployment period (days)

Deployment and retrieval of Chemcatcher

Sampling cage (lid removed)

Cage lid with Chemcatchers attached

Cage after two week deployment

Deployment of the Chemcatchers on site

The versatility of the Chemcatcher® passive sampler

Use of Chemcatcher®: case studies based on a problem solving approach

• We are currently building a portfolio of clients to highlight real case studies andapplications

• Most commercial work initiated from a problem solving approach e.g. screeningfor presence or absence of ecological relevant compounds.

• Expanding number of users and applications

• Creation of a central database of applications and calibration parameters.

• Central database will give better incentives to develop standardised calibrationmethods

• Expanding use at an European level

• Reinforces inter-comparison

• Provide alternatives to spot sampling and bio-monitoring

Radionuclides Chemcatcher®

• The Fukushima nuclear reactor incident in 2011 led to the large release of radioisotopesinto the environment

• Of particular concern was impact of radio-caesium in different environment compartments

• A commercially available caesium RAD-disk was available from 3M as part of theirEmpore™ range.

• The University of Portsmouth teamed up with the Chiba Institute of Technology , Tokyoand 3M Japan to investigate the use of this product as a receiving phase for Chemcatcher®.

• High affinity for Caesium enabling time integrative accumulation and lower detectionlimits.

• No need to collect large spot samples of potential radioactive water (~ 200 L)

• Various agencies in Japan have been undertaken to investigate the environmental fate ofradio-caesium and assess the effectiveness of different remediation measures.

Metals Chemcatcher®

• Metals in water can be sequestered using a Chemcatcher® fitted with an Empore™chelating disk.

• The performance of the device was investigated in relation to its application in regulatorymonitoring (e.g. European Union’s Water Framework Directive) of trace metals (e.g. Cd,Cu, Ni, Pb and Zn) in surface waters [5].

• The responsiveness of the sampler was evaluated for rapidly changing aqueousconcentrations of metals and clearly demonstrated its ability to react to transient pollutionevents

[5] Allan et al. (2007) Journal of Environmental Monitoring, 9, 672-681.

Table 1. Uptake rate of metals for the Chemcatcher® passive sampler [5]

Exposure conditionsVelocity = 70 cm s-1

Temperature = 18°C

Uptake rates (RS) of metals for the Chemcatcher® sampler(L day-1)

Cd Cu Ni Pb ZnMean 0.12 0.12 0.14 0.02 0.13

Standard deviation of Rs (%) 12 10 7 13 10

Polar organics Chemcatcher®

• Monitoring polar pesticides, pharmaceutical residues and associatedmetabolites and personal care products together with theirdegradation products.

• Several designs of Chemcatcher® are currently being used tosequester these types of chemicals.

• Moschet et al. (2014) used a Empore™ SDB-RPS receiving phase inconjunction with a polyethersulphone membrane for an in-situcalibration of the Chemcatcher® for 322 polar pollutants [1]

• For the majority of the substances there was a good correlationbetween those detected in water samples with those found on thereceiving disks.

[1] Moschet et al. (2014) Water Research 7 1 306-317

Polar organics Chemcatcher®

Non-polar organics Chemcatcher®

• This sampler uses a C18 Empore™ disk overlaid with a thin low-density polyethylenemembrane.

• In order to increase the uptake rate of analytes a small quantity of n-octanol is addedbetween these layers during manufacture.

• Recent applications of the device include the measurement PCBs, PAHs and DDT [2, 3]

• Using the same receiving phase with a cellulose acetate membrane the Chemcatcher® canmeasure organotin compounds including monobutyltin, dibutyltin, tributyltin (TBT) andtriphenyltin [4]

[2] Petersen et al. (2015) Environmental Science: Water Research & Technology, 218-226. [3] LOBPREIS, T. et al. (.2010) Acta Chimica Slovaca, 3, 81-94.[4] Aguilar- Martínez et al. (2008)

Table 2 Uptake rates Rs (L day-1) estimated by Petersen et al. (2015), Cw measured during the experiments and value of slopes and p-values of the linear regression curves of the test substances (The standard deviations are given in the respective ± columns)

Tap water

Seawater

Metaldehyde Chemcatcher®

• Molluscicide widely used on cereals and Oilseed Rape

• Very stable, high solubility and mobile in the environment

• Hard to remove from water even using advanced treatmentprocesses

• Has frequently exceeded 0.1 µg L-1 PCV (prescribedconcentration or value) in treated water since monitoringbegan in mid-2000s.

• NERC iCASE Studentship started at UoP (October 2014)

R.I.P.

Nutrients Chemcatcher®

• A recent addition to the family of devices is the development of a version for monitoringnutrients such as nitrate and phosphate [6]

• Here the sampler is fitted with an Empore™ anion-SR disk overlaid with a celluloseacetate membrane.

• The device was shown to selectively sample labile nitrate and phosphate species beingconfirmed by comparison of the analysis of spot samples using ion chromatography.

[6] Knutsson et al., 2013.

Fig. 2 Calibration curves for nitrate and phosphate at pH 7.0, 14°C, 200 rpm and concentration of 2 mg L-1

nitrate and 1mg L-1 phosphate [5]

Limitations and on-going work

Biofouling – we are currently working on new materials toovercome this limitation

Thank you for your attention!

http://www.port.ac.uk/research/chemcatcher/

chemcatcher@port.ac.uk

chemcatcher@chemcatcher

ISO standard

Development of a global (ISO standard)by Prof Richard Greenwood

On-going projects related to Chemcatcher®

Deployment and retrieval of Chemcatcher