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RA Series

RA-4300A Mercury Analyzer


Reducing-Vaporization Mercury Analyzer

Sensitive, accurate and multifunctional

RA-4300A is a benchtop Reducing Vaporization-CVAAS mercury analyzer which is designed and engineered with the necessary functions to fulfill all the needs in mercury analysis. 


Suitable for a wide variety of post-digested sample solutions, aqueous samples, including drinking water, industrial wastewater, river water, lake water, seawater and rain-runoff


USEPA 245.1  |  USEPA 245.2  USEPA 245.5  USEPA 7470A  |  USEPA 7471B  ASTM D 3223-17  EN-1483  APHA 3112  |  JIS K0102  ISO 12846 and more


High Productivity
- Autosampler with 80 Positions

RA-4300A is equipped with an autosampler of 80 positions which maximizes the throughput of any fast-paced laboratory, providing results with the shortest turnaround time possible.

Superior Detection Limit and Sensitivity
– Detection Limit Down to 0.5 ppt

RA-4300A is equipped with a Non-Dispersive CVAAS which has a detection limit of down to 0.5 ppt (5 ppt including sample digestion process) with excellent accuracy and precision.
With this superior detection limit and excellent precision, it provides a wide range of applications to be analyzed in RA-4300A such as river water, lake water, etc.

Built-In Reagent Dispenser

RA-4300A has a built-in reagent dispersing system for

  • Hydroxylamine hydrochloride
  • Tin (II) chloride
  • Sulfuric acid

The entire excess-oxidant quenching and reducing vaporization process is automated.

Discrete-Direct-Purge Technique of Reducing Vaporization

There are two methods of Reducing Vaporization, i.e.,

  • Flow Injection Technique
  • Discrete-Direct-Purge Technique.

All mercury analyzers in NIC employ Discrete-Direct-Purge Technique to minimize memory effect from mercury which causes cross-contamination issue.

Lower Operation Cost – No Carrier Gas Required & Reduced Consumption of Chemicals and Consumables

No Carrier Gas Required

Almost all CVAAS requires purified carrier gas such as nitrogen or argon. In RA-4300A, there is no carrier gas required which lowers down laboratory operation cost and facility preparation.

Reduced Consumption of High Purity Chemicals

When comes to trace mercury analysis, purity of the reagents plays a vital role in having minimum background that interferes with the target analyte measurement. Consumption of reagents directly relates to the daily operating cost.

Reduced Consumable Cost

RA-4300A built-in reagent pumps are incredibly long-lasting, durable, and consistent in the delivery of reagents such as hydroxylamine hydrochloride, tin (II) chloride, and sulfuric acid with excellent consistency. 

RA-4300A reagent pumps are operated as dosing mode, do not run continuously like those peristaltic pumps used in flow-technique, therefore extending its lifetime and maintenance frequency for both its tubing and motor.

RA-4500 Mercury Analyzer


CVAAS Mercury analyzer that automates from sample digestion to mercury measurement without operator intervention.

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WA Series

Mercury analyzer for ultra-trace level analysis in gaseous matrices. Featuring Dual Gold Amalgamation technique and various capacity options.

Differences between NIC Discrete-Direct-Purge Reducing Vaporization and other reducing vaporization techniques

NIC’s Discrete Direct-Purge Reducing Vaporization

In this technique, the mercury analyzer handles each sample in a Discrete, independent sample tube. Each sample is therefore isolated from surface contact with any other samples in the analytical batch to be measured.

The Direct-Purge technique is then used to extract and transfer the converted Hg0 from each sample tube and into the detector for measurement. Since only mercury vapor contacts the flow path, sample-to-sample memory effects and carryover from over-range samples are virtually eliminated.

How It Works

  • First, reductant (SnCl2) is automatically added into the sample tube containing the acid-digested sample solution. The sample tube is sealed, leaving a closed-loop flow path to the detector.
  • The carrier gas is introduced to sparge (or purge) the solution, releasing the elemental mercury vapor from the solution and into the flow path, which then flows directly into the detector for measurement.


  • Almost no sample-to-sample carryover or memory effect
  • Carryover from over-range samples is greatly reduced
  • Discrete technique only needs 200-300uL of reagent per sample
  • Reduces hazardous mercury wastes to less than one liter per full day of operation
  • Filtration of samples not required, as Direct-Purge technique can handle particulates in samples with no issues

Other Reducing Vaporization Techniques

  • Commonly based on Flow-Injection or Continuous-Flow Techniques to introduce the full sample solution into the system to complete the chemical reaction for the analysis.
  • The acidic sample solutions and reductant (SnCl2) enter the system via pump tubing with peristaltic pumping, which must be replaced often.
  • Chemical reduction begins when both the sample solution and reductant are mixed, reducing Hg2+into Hg0, within a continuous flow of reagents.
  • Prior to the detector, the liquid-gas phase separator or membrane separation device is needed to remove the liquid, allowing the Hg0gas to enter the detector.

Mercury is well-known for its strong affinity to absorb onto different materials and its high solubility in acidic reagents.

After the digestion and oxidization procedure, samples are usually very acidic. The acidic sample solutions and reductant, SnCl2, enter the system via pump tubing with peristaltic pumping. The acidic sample leaves a residue on the inner surface of pump tubing, creating possible active sites for mercury absorption from current mercury, which is easily passed on to the following samples.

Such phenomenon is inevitable with this technique and commonly exhibits as what is called the mercury memory-effect, experienced by many lab analysts. This effect is especially significant and severe when analyzing samples of varying mercury concentration levels.

Large multi-liter carboys of hazardous waste are produced daily from such flow-based techniques, creating the need for expensive waste disposal. Reduction of hazardous mercury wastes should be a priority for all mankind, and it is a priority of the Minamata Treaty

How Does it Reduce Reagent Consumption?

Less Reagent Consumption, Less Waste Generation Compared to Flow-Injection Technique

Generally, the flow-technique system continuously pumps and flows the reagents through the system to stabilize the dynamic flow to get a consistent flow (sample) volume which is crucial for precise quantification purposes. Secondarily, the reagents used for the analysis are pumped continuously through the system to clean the flow paths and obtain a constant background. Overall, multiple milliliters per minute of liquids are used and generated as waste.

In discrete-direct-purge technique, much lesser reagents are consumed. This technique uses a fixed volume of reagents per sample analysis. Typically, only just 0.3 milliliter of reductant (SnCl2) is consumed per run.

Less usage of reagents which are generally acidic, generates less hazardous waste for disposal, saving the operating cost in both ways.

Similarly, for sample solution, NIC reducing vaporization normally uses fixed 5mL sample volume for analysis. As for flow technique, sample solution is continuously pumped through the system to complete the reaction with the reductant. Depending on the flow rate setting, typically each analysis generates between 7 to 10mL of liquid waste.