Lumex RA-915+ | Mercury Vapor Meters | Mercury Monitoring Equipment

Design features

The RA-915+ mercury analyzer employs differential atomic absorption spectrometry technique, which is implemented using the direct Zeeman effect (Zeeman Atomic Absorption Spectrometry using High Frequency Modulation of Light Polarization ZAAS-HFM). A glow discharge mercury lamp is placed in a permanent magnetic field, whereby the 254-nm mercury resonance line is split into three polarized components, only two of those, s+ and s-, which are circularly polarized in the opposite directions, being detected for analysis. After passing through a polarization modulator, which modulates the polarization at a frequency of 50 kHz and thus triggers the line components in turn, the radiation then passes through a multi-path cell, whose equivalent optical length is about 10 m. Being equipped with narrow-band high reflectivity mirrors, the cell isolates solely the 254-nm resonance line and suppresses all the nonresonance and stray radiation. A logarithm of the intensity ratio of s+ and s-, which is proportional to the mercury atom concentration in the cell, is determined upon detecting the radiation by a photodetector and subsequent analog-digital conversion of its electric signal by a built-in microprocessor. The measurement results are read out from a built-in LC display, or are transmitted to a computer for further processing or data storage. In this measurement technique, the analytical signal depends only on mercury concentration and is independent of the presence of dust, aerosols , and other foreign contaminants in the analytical cell.

Water analysis

An RP-91 attachment is used for the mercury determination in water by the «cold vapor» technique. A reducing agent, SnCl2, is added to a sample, and the atomic mercury thereby released is conveyed to the analytical cell by a carrier gas. The ultimate mercury detection limit in water solutions is 0.6 ppt (ng/l), the sample volume being 10 ml and the analysis time being no more than 90 sec.

Analysis of complex matrix samples

An analysis is carried out using an RP-91C attachment, wherein mercury is converted from a bound state to the atomic state by thermal decomposition in a two-section atomizer. The sample is vaporized in the first section, and the mercury compounds are partly decomposed. In the second section, which is heated to 800° C, the mercury compounds become fully decomposed, organic compounds and carbon particles are catalytically after burnt, to carbon dioxide and water. This technique is used to determine mercury in soils, food products, biological samples, and crude hydrocarbon products, no preliminary sample mineralization being needed and the analysis itself taking 1-2 minutes.

Specifications

• Size and weight (with a storage battery and recharger): 460x210x110mm, 7.58 kg
• Power requirements: 110/220V, 50/60Hz 15W AC or 10-14V DC

Analytical characteristics

Samples	Detection limit	Sample volume or weight	Atomization technique	Number of analyses per hour
Ambient air	2 ng/m3	20 l/min	without atomization	*)
Natural and other gases	2-500 ng/m3	5 - 20 l/min	without atomization	*)
Water	0.5 ng/l	20 ml	cold vapor	15
Oil and condensate	50 µg/kg	10 mg	pyrolysis	15
Solid and sediments	0.5 µg/kg	200 mg	pyrolysis	15
Urine	5 ng/l	1 ml	cold vapor	15
Tissues	5 µg/kg	10 mg	pyrolysis	15
Hair	20 µg/kg	10 mg	pyrolysis	15
Blood	0,5 µg/l	0.2 ml	cold vapor	15
Plants	2 µg/kg	50 mg	pyrolysis	15
Foodstuff	2 - 10 µg/kg	5 - 50 mg	pyrolysis	15

*) Real-time assaying with a response time of 1 sec.