Direct Mercury Analyzer with Thermal Decomposition and Amalgamation

What is the Direct Mercury Analyzer with Thermal Decomposition and Amalgamation?

A direct mercury analyzer thermally decomposes solid or liquid samples and traps mercury on gold for atomic detection. It is chosen for fast, reliable food, soil and waste testing that avoids acid digestion.

Overview

In this instrument the weighed sample, either solid or liquid, is placed in a boat and heated in a stream of oxygen. Combustion and decomposition release mercury as vapor along with combustion products. Water and acid gases are removed by a catalytic section and moisture trap, and mercury is captured on a gold amalgamator. The amalgamator is then heated to release mercury into an atomic absorption cell or atomic fluorescence detector at 253.7 nanometres. Because there is no acid digestion, contamination and analyte loss are reduced, and a sample can be measured in about five minutes. Sequences use an autosampler for boats, and calibration is performed with certified solid or aqueous standards. The technique is widely used for food, soil, sediment, waste and geological samples.

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?

• Thermal decomposition in an oxygen stream
• Gold amalgamation for mercury trapping
• Catalytic and moisture removal stages
• Atomic absorption or fluorescence detection at 253.7 nm
• Autosampler for sample boats
• Measurement in about five minutes per sample

What are the technical specifications?

A typical direct mercury analyzer with thermal decomposition and amalgamation configuration offers measurement range of 0.05–1000 ng, detection limit of 0.001 ng absolute, sample types of solid, liquid, slurry, sample mass of 10–500 mg, measurement time of approximately 5 min and combustion temperature of up to 750 °C. 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 Direct Mercury Analyzer with Thermal Decomposition and Amalgamation is used in mercury in fish, rice and food products, soil, sediment and waste mercury screening, geological and mining samples and solid pharmaceutical and chemical 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 21 CFR Part 11 software 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 Direct Mercury Analyzer with Thermal Decomposition and Amalgamation?

Select the direct analyzer when solid or complex samples must be measured without digestion, when trace mercury is required, or when contamination from reagents is a concern. Specify the sample types, expected concentrations and throughput. Confirm that certified solid reference materials are available and that combustion conditions suit your matrix, especially for high organic content.

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.