Manufacturer & supplier of heavy metal and environmental analysis instrumentation for the global market The Technology to Test

METALYSER HM1000 Portable Heavy Metals Analyser Measurement in water of Arsenic, Cadmium, Copper, Lead, Mercury and Zinc to ppb levels quickly and accurately in the field

Introduction Context – heavy metals in water Quick summary of Anodic Stripping Voltammetry (ASV) Introduction to the Metalyser Operating procedure Features and benefits Conclusions

Overview Contamination of our water resources by toxic heavy metals is increasingly becoming a problem the world over Widespread industrial and urban pollution is responsible for introducing these heavy metals into the environment This problem is particularly acute in the developing world where unchecked industrial growth, lack of monitoring facilities and failure to enforce environmental regulations has worsened the situation

What is a Heavy Metal? »Tends to be categorised as either: »Metallic elements with high relative atomic mass, high atomic weight or high density »Many are toxic even at very low concentrations »Some heavy metals are essential to human life - for example, copper »Heavy metals bio-accumulate in the food chain – plants, fish, aquatic life, animals »Humans eat all of the above »Accumulation can cause serious health problems

Why are Heavy Metals in the Environment? »Some heavy metals, for example lead and copper, are geological and leach from rocks »Some, for example mercury and cadmium, are typically anthropogenic and come from human activities and processes »Some, for example arsenic, can come from both sources

“Between 1850 and 1990 production of the metals lead, copper and zinc have increased exponentially, to nearly 10-fold” from “Heavy Metals and Health”, World Resources Institute Heavy Metals in the Environment Source: J.O.Nriagu, “History of Global Metal Pollution,” Science, Vol. 272 (April 12, 1996), pp

WHO Guideline Values Parts per billion (ppb) concentrations for trace metals in potable (drinking) water »Arsenic (As)< 10 ppb »Cadmium (Cd)< 3 ppb »Copper (Cu)< 2000 ppb »Lead (Pb)< 10 ppb »Mercury (Hg)< 6 ppb Values for the most dangerous heavy metals are very, very low; cadmium is < 3 parts per billion (ppb)

“National and international funding bodies should fund research programmes to develop portable field- testing kits for [heavy metals] that are quick, accurate, cheap and reliable and support remediation efforts.” From: Sustainable Water: Chemical Science Priorities summary report, Royal Society of Chemistry, 2007

Metalyser HM Main Components Mounted within the handheld unit »Potentiostat »Current recorder »Data Processor The Metalyser uses the technique of Anodic Stripping Voltammetry (ASV) and has 2 main components: -the Sonde -the Handheld unit Mounted within the Sonde »Electrodes »Temperature probe »Stirrer motor & paddle

COUNTER ELECTRODE STIRRER TEMPERATURE SENSOR (behind counter electrode) WORKING ELECTRODES (x2) REFERENCE ELECTRODE SONDE Metalyser Sonde Key Components

What is Anodic Stripping Voltammetry (ASV)? »ASV is an analytical electrochemical testing method. Electrochemical techniques were first theorised in 1922 by Jaroslav Heyrovsky »Electrochemistry has many applications but in this case is used for heavy metal analysis to low ppb »Although developed around 80 years ago, modern electronics and software technology have enabled ASV to be used in truly portable systems ASV is widely recognised and has the following method approvals: »US EPA Method 7063 (As) and 7472 (Hg) »DIN , part 16, Zn, Cd, Pb, Cu, Tl, Ni, Co

Analysing a sample

CE = Counter Electrode RE = Reference Electrode WE = Working Electrode A = Current in micro amps (µA) V = Potential in millivolts (mV) A V CE REWE CdX → Cd 2+ + X +2e - Cd 2+ + X + 2e - → CdX Cd 2+ The METALYSER uses a 3 electrode system which allows for a much wider range of applications over a 2 electrode system and provides more reliable control of the system potentials (voltage) A simple diagram of the cell (located in the Metalyser Sonde) is shown below: Deposition step Cd 2+ Sweep step Cd 2+ ASV overview ReductionOxidation

Electrodes s 3 electrodes are used - i.e. Working, Counter and Reference; 1. Working Electrode - where the main electrochemical reaction occurs 2. Counter Electrode - carries the current, which flows through the working electrode. Its function is to prevent the working electrode from carrying any current which would change its potential, and hence make the analysis highly irreproducible 3. Reference Electrode - forms no part of the electrochemical reaction and is simply used to control the Potential (voltage) W C R W C R

Operation – 1 st Conditioning 1.Polish working electrode using polish pen 2.Rinse Sonde head with demin including electrodes and stirrer 3.Place Sonde head into M1&4 or M2&3 conditioning solution 4.Run M(no) Conditioning program to plate working electrode 5.Check tip of working electrode to determine a successful plate 6.Remove SAB and rinse with demin water 7.Run Conditioning program on metals menu to prepare electrode for analysis

Deposition »A stirrer ensures the concentration of ions is homogenous throughout the cell during the deposition process »The working electrode is given a large negative potential of up to -2,000 mV »The positive metal ions are attracted to the negative cathode (working electrode) Pb CE RE WE Potentiostat and electronic controller Stirrer on -ve potential applied to WE STIRRER

»Deposition is a concentration step. The longer the potential is held, the more metal reduces on the working electrode »Current produced is proportional to the metal deposited »The more metal present, the larger the current that will be produced during the analysis phase Deposition Pb CE RE WE Potentiostat and electronic controller +ve ions attracted to WE tip +ve ions reduced to metal STIRRER -ve

»The instrument scans from an initial plating potential to a pre-defined end potential »When the scan potential reaches the redox potential of a metal the metal oxidises, releasing electrons, which then generate a current »The current produced is proportional to concentration Stripping Pb CE RE WE Potentiostat and electronic controller WE sweeps more +ve ions removed from WE current produced STIRRER +ve e-e- e-e- e-e- e-e- Measured current

»If the potential is set below the Redox potential of a metal it will not be reduced onto the electrode »This means that only the metals with the correct Redox potential will be analysed ignoring the others, in this example the cadmium Selectivity Pb CE RE WE Potentiostat and electronic controller +ve ions selectively attracted to WE tip STIRRER Cd -ve

Summary of Events Needed for an Analysis Stirrer on Clean Deposition Sweep or strip step Final strip Clean An example of a typical run for ASV Clean – potential is applied above potential the heavy metal is removed Deposition – working electrode is held at negative potential for an accumulation time (60 secs default) Sweep – polarity is reversed and heavy metals are removed Final strip – potential taken beyond the potential which the metal of interest is removed at to ensure all the metal is stripped off Note: the stirrer does not operate during the course of the entire run Operation of the stirrer is indicated on the handheld by the symbol:

Typical ASV scan of current (µA) against potential (mV) Cd Pb Peak height (current) is proportional to concentration Voltammogram shows spiked samples of increasing concentration

Summary »ASV measures low ppb quickly and accurately »The Metalyser is a technical instrument »Metalyser HM1000 has been designed with end user in mind »Buffers are solid and hence have long shelf life »No complicated lab procedures undertaken in the field

METALYSER HM 1000 F&Bs Benefits: »Rapid detection of heavy metals down to ppb levels »Low cost per test »Storage of up to 1,000 results on internal data logger »More cost-effective than other instruments on the market »Measurements taken directly at source Features:  Currently measures 6 parameters in water; As, Cd, Cu, Pb, Hg, Zn »Parameter range can be extended in future using the same instrument »Rapid results - typical analysis time ~2 mins »No hazardous reagents - pre-weighed powder used as a buffer in the sample »User-removable electrodes »Robust & waterproof design to IP67  Immersible Sonde head »USB/ Bluetooth (optional) outputs allow data to be sent to a PC »Minimum training required – step-by-step analysis guides provided

Conclusions »Metalyser uses ASV to measure heavy metals to low concentrations, quickly and accurately »Simple and quick test procedure with pictorial guides »Need to consider where the Metalyser will be used and remember it does have limitations »Unique Sample Analysis Beaker (SAB) system allows for convenient sampling and analysis in one go

Please come and visit us at Hall A2, stand 138