Sample digestion and mercury measurement according to EN 1483

The RA-4500 is a fully automatic discrete CVAAS mercury analyser with integrated acid digestion.

The mercury analyser with fully automatic sample digestion

The RA-4 instrument series from Nippon Instruments Corporation enables fast and easy determination of mercury in the ultra trace range from samples from which mercury can be released under reducing conditions. Possible samples are: Drinking water, groundwater, seawater, wastewater, surface water, rainwater, all types of digestions (e.g. aqua regia or microwave) from solid or liquid samples.

The special feature of the RA-4500 is that it can perform the permanganate digestion (compliant with EN 1483) fully automatically. Without external intervention, the digestions are then analysed fully automatically. From sample digestion to final measurement, all steps are fully automated:

– Reagent dosing (all 6 reagents required)

– Staining test

– Thermal digestion for 2 hours in an aluminium block

– Cooling of the digestions

– Reduction of excess potassium permanganate (KMnO4) with hydroxylammonium chloride (NH2(OH)HCl)

– Release and mobilisation of the mercury by reduction with tin(II) chloride (SnCl2)

– Final detection by cold vapour AAS (CVAAS)

The system can automatically process up to 80 samples in one analysis run under computer control. The high degree of automation minimises the influence of manual handling and leads to time and money savings.

It is also possible to process samples that have already been digested directly. In the compact design, mercury can be determined in the measuring range between 0.5 ppt and 100 ppb using the proven atomic absorption technique (CVAAS).

The devices of the RA-4 series have a unique design. They work as discrete analysers where, in contrast to flow injection systems, the preparation of the samples and the expulsion of the mercury are carried out completely in the sample vessel. The devices are completely enclosed. The AAS systems also work completely without an external gas supply. The RA-4500 has an active extraction system that can be connected to an existing exhaust air system if necessary.

The RA-4500 is also characterised by its uniquely low reagent consumption: On average, less than 3 g potassium permanganate and hydroxylammonium chloride, as well as 4 g tin(II) chloride are required per 100 samples.

Figure 1: RA-4500

Key features

– CV-AAS with fully automatic sample digestion according to EN 1483

– Autosampler with 80 positions

– Excellent analytical performance over a wide measuring range

– Minimal carry-over due to discrete measurement according to the batch method

– Operation independent of laboratory gases

– High level of safety (control functions, enclosure with extraction function)

– Easy access to all relevant components

– Low operating and consumable costs

– Easy handling and intuitive software

– Low space requirement

Parameters / Elements

– Mercury

Measuring method

– Presentation of samples in vessels

– Automatic dosing of reagents into the sample vessel

– Digestion according to EN 1483

– Reduction of excess oxidant

– Addition of tin(II) chloride

– Mixing of the sample and mobilisation of the mercury

– Gas drying with subsequent detection by AAS

– Automatic rinsing step

Industries and branches

– Environment

– Foodstuffs

Use and applications

Determination of mercury content in drinking water, groundwater, seawater, wastewater, surface water, rainwater, etc. including sample digestion. In addition, all types of digestion solutions (e.g. aqua regia or microwave).

Standard methods

The RA-4500 conforms to the following standard methods, among others: DIN EN ISO 12846, DIN EN 1483, ASTM D3223, APHA 3112, JIS K0102, USEPA 245.1, USEPA 245.2, USEPA 245.5, USEPA 7470A, USEPA 7471B, DIN ISO 16772, ISO 5666

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Product details


– Method: Discrete mercury reduction

– Digestion according to EN 1483

– Addition of reagents in batch process

– Detection: Cold vapour atomic absorption spectroscopy

– Measuring range: 0.5 ppt to 100 ppb

– Gas supply: no external gas supply necessary

Software and use

The RA-4500 is controlled by a special control software which allows intuitive use. Quick start-up, easy set-up of sequences for digestion and measurement including calibration, easy visualised results, stand-by functions, extensive reporting, numerous diagnostic and service tools. The software offers everything necessary for simple and robust operation and runs under Windows.

Figure 2: RA-4500 Software


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