Mercury Analysis 31
your decision; with the knowledge that CVAAS will provide a detection limit of about 2 ppt and CVAFS will provide a detection limit of about 0.2 ppt (or as low as 0.02 ppt with gold amalgamation). With that said, unless you have a preference for CVAAS, our recommendation is that you consider CVAFS. Its superior detection limits will allow you to report to lower levels and its wider dynamic range will be a real time saver from the perspective of not having to do as many sample dilutions.
If your sample is a solid you have the choice of digesting the sample and then analysing it by CVAAS or CVAFS. Alternatively you may be able to skip the digestion step and go with direct analysis by thermal decomposition.
Hydra-C Mercury Analyzer with Thermal Decomposition
Answering a few simple questions will guide you in the direction of the technique which is right for you.
The fundamental question is, is your sample a solid or a liquid?
If your sample is a liquid (e.g. wastewater, drinking water, etc.) then you will most likely be best served by one of the chemical reduction techniques of CVAAS or CVAFS.
At this point you can let your detection limit requirements drive
For many labs, the simplicity of direct analysis is very appealing. For labs that already have digestion procedures in place the higher capital cost of direct analysis relative to CVAAS (or CVAFS), could be up to $10k, may drive the decision. Other factors, such as the sample heterogeneity or volatility may be important considerations as well. Because direct analysis is limited to a relatively small quantity of sample (about 1 gram), inhomogeneous samples may be best dealt with by digesting a larger quantity of sample followed by analysis using CVAAS or CVAFS.
Additional assistance with your decision about which mercury analysis technique is right for you can be found at
www.teledyneleemanlabs.com/hg_selector.
(1) Persistent bioaccumulative and toxic chemical program,
EPA.gov/pbt.
(2) W.R. Hatch and W.L. Ott, Anal. Chim. Acta, 40, 2085–7 (1968).
(3) Analytical Methods Approved for Drinking Water Compliance Monitoring of Inorganic Contaminants and Other Inorganic Constituents,
http://water.epa.gov/scitech/drinkingwater/labcert/upload/methods _inorganic.pdf.
(4) Method 245.7, Mercury in Water by Cold Vapor Atomic Fluorescence Spectrometry, Revision 2.0, February 2005, U.S. Environmental Protection Agency.
(5) Method 1631, Revision E:Mercury in Water by Oxidation, Purge and Trap, and Cold Vapor Atomic Fluorescence Spectrometry, August 2002, U.S. Environmental Protection Agency.
(6) National Recommended Water Quality Criteria (4304T), 2009, U.S. Environmental Protection Agency, (Federal Register: August 5, 1997 62[150]).
First published in International Environmental Technology 21.5 September/October
Mercury Instrument Hire Helps Protect Oil Rig Safety
Portable mercury monitors hired from instrumentation specialist Ashtead Technology (UK) have enabled the rapid assessment of working conditions for safety specialists undertaking vital maintenance checks on oil rigs in the North Sea.
RBG, the leading provider of inspect, assess and repair (IAR) services to the global energy industry, has been using advanced Jerome J405 Mercury Analysers to monitor conditions on a number of rigs prior to maintenance and safety inspections.
RBG’s Technical Support Engineer Colin Bones explained that the portable J405s are regularly hired from Ashtead Technology for rentals of varying lengths; from a few days to six months.
He said: “Alongside other gas detection work on the rig, the J405s help us determine potential exposure levels for when further work, such as tank and vessel entry. By deploying the J405s at this preliminary stage we are able to identify the correct personal and respiratory protective equipment, such as full face respirators or SR100 half face masks which minimise the potential for exposure.
“Once the monitoring has been undertaken and we have established a safe working environment, we are then able to carry out any maintenance work required. This can vary from splitting pipework and flanges, removing sludge and contaminants from tanks, to inspecting and cleaning pipes.
“Because the frequency of this work can be irregular we decided that a standard rental from Ashtead Technology best suits our needs and provides us with instant access to advanced instrumentation to ensure we can react to client demands.”
The J405 utilises the industry-proven and reliable gold film sensor technology and simple, one-button operation. Key features include improved ergonomics from previous versions, a larger display as well as improved data storage, retrieval and communications. It can be used across a wide range of mercury-related applications, including mercury spill response, landfill monitoring and hazardous waste analysis.
Alan Hasson, Ashtead Technology’s General Manager, added: “This application highlights the many benefits of instrument rental. The instruments were delivered tested and ready for immediate deployment, which meant that RBG was able to save time in preparing for the work. At the end of the hire period, instruments are simply returned to us, so there are no ongoing maintenance or storage costs.
“Our overall aim at Ashtead Technology is to put the right instruments into the hands of those that need them; which means that we need a large fleet of the latest technologies, a high level of technical support and a range of financial packages that meet customers’ differing needs."
Reader Reply Card No. 82
New Mercury Analyzer Hydra IIAA Where PERFORMANCE and PRODUCTIVITY Meet
PERFORMANCE • 1 ppt Detection Limit
• Dynamic range from ppt to ppm
• Handles difficult samples
• Stability < 2 ppt per hour
• Direct Analysis Option eliminates sample prep
Mercury Analyser for Rigorous Methods
The M-8000 from CETAC Technologies (USA) is designed to make some of the most rigorous methodologies simple. The QuickTrace software ensures the validity of every aspect of the unique calibration techniques by EPA 1631 and 245.7 methods. In software, it can be easily switched from high concentration analysis to ultra-trace analysis with the use of gold traps.
The QuickTrace software is easy to learn, yet provides valuable features and flexibility. Automated calibrations, sample analysis, quality control and report generation, are built in, satisfying the most demanding sample throughput and quality control requirements.
CETAC offers a filtered enclosure specifically for the autosampler, minimising particulate contamination and expensive clean-room space. Components of the M-8000 are easily accessible for user maintenance. Timely Customer Service support is partnered with a loaner instrument program that guarantees maximum operability.
Reader Reply Card No. 83 Reader Reply Card No. 84 Hg Analysis.
Visit
www.LeemanLabs.com/Hg or call 1-603-886-8400 today!
PRODUCTIVITY
• High Capacity Autosampler – Up to 270 samples – Large CCV & CCB reservoirs
• Powerful Over-Range Protection
• Unparalleled Support – Built-in maintenance schedules
– On-line audio/visual help
– Extensive field service network
Don’t settle for just any Mercury Analyzer. Go with the experts in
AET October/November 2011
www.envirotech-online.com
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