Cold Vapor Atomic Absorption Mercury Analyzer

What is the Cold Vapor Atomic Absorption Mercury Analyzer?

A cold vapor atomic absorption mercury analyzer reduces mercury in solution and measures its vapor by absorption. It is a robust, economical choice for water, digested solids and industrial samples at microgram per litre levels.

Overview

The sample is acidified, and tin chloride or sodium borohydride reduces mercury to its elemental form. A carrier gas, usually argon or nitrogen, sparges the mercury vapor from the liquid into a gas-liquid separator and sweeps it through an absorption cell positioned in the light path of a low-pressure mercury lamp. Absorbance at 253.7 nanometres is proportional to mercury concentration, and integration of the transient peak or measurement of the steady signal gives the result. Amalgamation on gold may be added to concentrate mercury and remove interferences, especially for seawater and low-level samples. Calibration uses aqueous mercury standards, and reducing reagent and acid concentrations are fixed in the method. Typical detection limits are 0.05 to 0.5 micrograms per litre, and throughput suits routine environmental and industrial testing.

How does it work?

Mercury is unique among metals because it is volatile at room temperature and forms a stable amalgam with gold. Most analyzers exploit one or both properties. In cold vapor atomic absorption, mercury in solution is reduced to elemental form with tin chloride or sodium borohydride and swept into an absorption cell where it absorbs the 253.7 nanometre line of a mercury lamp. Cold vapor atomic fluorescence uses the same generation step but detects emitted light at right angles for higher sensitivity. Direct analyzers heat the solid or liquid sample to release mercury, which is collected on a gold amalgamator, then desorbed into a detector. Ambient air and emission monitors use gold amalgamation or optical techniques such as Zeeman atomic absorption or ultraviolet absorption for continuous measurement. Calibration uses certified mercury standards and gas-phase generators, and all systems require careful control of contamination because mercury is ubiquitous in laboratories.

What are the key features?

• Reduction with tin chloride or sodium borohydride
• Gas-liquid separator and absorption cell
• Low-pressure mercury lamp at 253.7 nm
• Optional gold amalgamation for concentration
• Transient peak or steady signal measurement
• Simple, robust reagent chemistry

What are the technical specifications?

A typical cold vapor atomic absorption mercury analyzer configuration offers detection limit of 0.05–0.5 µg/L, measurement range of 0.1–100 µg/L, wavelength of 253.7 nm, reductant of tin chloride or sodium borohydride, carrier gas of argon or nitrogen, 200–600 mL/min and absorption cell path of 100–300 mm. Values are indicative of the product class; the exact figures for each configuration are confirmed on the quotation and the calibration documents supplied with the instrument.

Which applications is it used for?

The Cold Vapor Atomic Absorption Mercury Analyzer is used in mercury in drinking water and wastewater, digested soil and sediment samples, industrial effluent and process solutions and food digests and chemical raw materials. Across the wider Mercury Analyzers class, laboratories also deploy it for mercury in fish, rice, seafood and food products, drinking water, wastewater and seawater monitoring and soil, sediment and contaminated site assessment.

Which standards and certifications apply?

Relevant standards and methods include US EPA Method 7473 Mercury in solids and solutions by thermal decomposition, US EPA Method 7470A Mercury in liquid waste by cold vapor AAS, US EPA Method 1631 Mercury in water by oxidation, purge and trap, and CVAFS, ISO 12846 Water quality — Determination of mercury by AAS after enrichment, ISO 20552 Workplace air — Determination of mercury vapour by gold amalgamation, EN 15852 Stationary source emissions — Determination of total gaseous mercury and IEC 61010-1. Certification candidates for this model are CE, ISO 9001 manufacturing and IEC 61010-1 safety compliance; each is to be confirmed for the specific configuration before shipment, and certificates are supplied only where they have been issued.

Mercury is toxic by inhalation and accumulates, so laboratories must control vapor exposure, use ventilated enclosures and monitor ambient air. Contamination is a constant risk because mercury appears in reagents, dust and previous samples, so ultrapure reagents, dedicated glassware and rigorous blanks are essential. Gold amalgamators require periodic cleaning or replacement when recovery falls. Calibration standards and gas generators must be traceable, and reducing agents must be fresh. Luminaires and detectors for the 253.7 nanometre line need stable temperature. For emission and ambient monitors, sample lines must be heated and inert to prevent mercury loss. Maintain service records and follow local occupational exposure limits and waste disposal rules.

How do I select the right Cold Vapor Atomic Absorption Mercury Analyzer?

Select cold vapor atomic absorption for routine water and digested samples where detection limits around 0.1 microgram per litre are adequate and cost and robustness matter. Specify the sample types, expected range and whether gold amalgamation or an autosampler is needed. Confirm that the method you follow specifies this detection principle.

How does it compare with other Mercury Analyzers variants?

Select a mercury analyzer by sample type and required detection limit. Direct thermal decomposition analyzers handle solid and liquid samples in minutes with minimal preparation and reach low nanogram levels, which suits food, soil and waste testing. Cold vapor atomic absorption is a robust, economical choice for water and digested samples at microgram per litre levels. Cold vapor atomic fluorescence reaches much lower limits and suits ultratrace water and seawater work. Portable ambient air analyzers with gold film or Zeeman detection serve workplace and indoor air surveys. Continuous emission monitors and total mercury analyzers with gold amalgamation are installed on industrial stacks and process streams. Confirm the measurement range, sample throughput, calibration approach and whether a specific regulatory method is mandated.