Mercury Lab Analyser AULA 254

Automatic Mercury Analyser AULA-254: autosampler - reaction unit
Fully automated flow analysis system
Modular Construction
Proven and reliable detection method:
cold vapor atomic absorption (CVAAS)
Automated Sample Digester Module (ASD)
as an optional accessory
GoldTrap Enhancement Option
for maximum sensitivity of <1 ng/l
Fields of application

The AULA 254 is used for fully automatic determination of mercury traces in a wide variety of samples. The instrument carries out routine analysis: sample after sample following exactly the preselected procedure thus increasing efficiency and productivity of your lab. Applications include:

  • Water, Waste, Soils and Effluents
  • Applicable to EPA Methods: 245.1, 245.7, 1631, 7470 and 7471A
  • Medicine (urine, blood, saliva, hair)
  • Chemical industry (process monitoring, quality control)
  • Geochemistry (geological and mineralogical samples)
  • Petrochemistry
  • Metallurgy and material testing

Reliable and proven method
The working principle of the system is based on the continuous flow method. First the mercury contained in the sample is transformed into the elemental state by addition of a reducing agent to the sample flow. In a crossflow reactor the mercury is stripped with a gas stream and carried into the optical cell which is made entirely of fused silica. There the quantitative determination of mercury is obtained by measuring UV absorption at a wavelength of 253,7 nm at room temperature. This analytical technique is commonly known as cold vapor atomic absorption spectrometry (CVAAS), a method that has proved itself as extremely sensitive and selective over many years.

Optimized mercury detection technique

In contrast to a typical multi-element AAS the AULA is specially designed for mercury determination. This allows top performance in analytical applications. The use of a highly stable low-pressure electrodeless mercury discharge lamp (EDL) in connection with the latest UV detector techniques result in excellent baseline stability and low detection limits.


AULAWIN software
Surprisingly easy to use the AULA-WIN offers all features of a modern analytical software. It has been developed with extensive input from our users. Samples, calibration standards and quality control standards (QCS) are entered into the carrousel screen. With an optional barcode stick sample data can be entered comfortably. A sample table is created automatically and can be viewed in the table screen. Sample dilution factors as well as sample weight and final fill up volume for digestion of solid samples can be entered in the table. The result of the measurement is calculated automatically from the chosen calibration function and displayed in µg/l or µg/kg. The QCS function assures a high level of reliability of the analytical results.

Data storage
The results of the analyses together with the data necessary for quality assurance (date, time, user ID, sample number, calibration data, instrument parameters) are stored in a file. They are available at any time for display and printout. Worksheet templates can be created and stored to minimize setup time for routine work.

High productivity
No long purging or rinsing procedures even when samples with high concentrations are analyzed. The typical duration of a full measurement cycle is 80 ... 280 seconds. The quick screening mode allows performing analyses in even a shorter time.

How measurement is performed

Measurements of up to 20 calibration standards and up to 53 samples and check standards are carried out fully automatically. Standards and samples are filled into 10 ml glass vials and positioned on the autosampler turntable. Reagent solution (for example tin-(II)-chloride) and rinse solution (reagent water) are filled in the corresponding glass tanks. Then the stripping gas flow is adjusted and measurement is started by a keystroke. The measurement cycle can be interrupted at any time by the operator for selecting any sample to be measured next. Readings and instrument status are displayed in real-time on the screen.

Automatic baseline correction
The stability of the baseline is checked prior to each measurement and the zero point is adjusted automatically. The typical zero drift during a measurement is below 0.0001 absorbance units.

Minimized memory effects
Mercury vapor has a general tendency to absorb on surfaces causing a memory effect. This undesirable property has been minimized by using selected materials (fluoropolymer, borosilicate glass, Tygon LFL) for sample and reagent conducting components and by heating the optical bench. In addition, the autosampler probe and the sample tubing are rinsed after each sample. This also allows a high sample throughput. Even samples with concentrations in the upper measuring range do not produce a carry over to the following sample.

Thermoelectric dehumidifier
Unlike traditional mercury analyzers, which use drying tubes for removing water vapor from the sample gas, the AULA 254 uses a maintenance-free thermoelectric dehumidifier. The dew point of the gas is decreased below ambient temperature thus the water condenses on the wall of a small glass tube and flows back into the reactor.

Carrier gas flow stabilization with MFC
The stability of the carrier gas flow has a direct effect to the reproducibility of measurements. For this reason the AULA 254 system uses a highly precise (1.5 % accuracy) electronic mass flow controller (MFC).

Safety for the user
The mercury cannot escape into the working environment, as any free mercury is collected in a sulfurized activated carbon filter. A message appears on the screen if the cartridge needs replacement. Thus an installation of a fume hood is not required.

Automatic protective system cleaning
The instrument automatically interrupts the measurement if samples with mercury concentrations exceeding the measuring range are detected. In this case the system is immediately cleaned.

Automated sample digestion module (ASD)

The AULA 254 can be equipped with an optional sample preparation system for aqueous samples. The digestion procedure derives from standard methods commonly used in the laboratory.

The sample is automatically drawn from the autosampler vial and is continuously mixed with a strong oxidizing reagent (e.g. potassium permanganate, bromide-bromate). Subsequently the sample/oxidant mixture is heated to ca. 98¡C in a heated coil. After the oxidation step hydroxylamine hydrochloride and tin-(II)-chloride are added for reduction of mercury into the elemental state.

The AULA-ASD is economical. Average reagent consumption for 100 analyses is:

10 g hydroxylamine hydrochloride
1-5 g potassium permanganate
20 g tin-(II)-chloride
5 l water (deionized)


Make your system even more sensitive: GoldTrap

The optional GoldTrap preconcentration module drastically enhances the detection limit to values lower than 1 ng/l. Using ultrapure reagents and following the guidelines for mercury analysis at ultratrace levels (e.g. given in EPA method 245.7 or method 1631) a measuring range from 1 ppt to 5000 ppt can be achieved. This complies with the performance data given in EPA method 245.7 or 1631.

An outstanding property of the newly developed GoldTrap is itÕs minimum thermal inertia. This has become possible by use of a wafer thin ceramic substrate. As a consequence heating and cooling rates become very fast. Analysis durations are comparable to the direct method.

Having the GoldTrap installed, the user can select if analyses shall be carried out with or without a preconcentration step. This makes the instrument versatile for any application.

AULA 254 Technical Specifications
Measuring principle: UV-Absorption, cold vapor technique (CVAAS)
Analytical wavelength: 253,7 nm
UV source: Electrodeless low-pressure mercury discharge lamp
Stabilization method: Reference beam technique
Optical cell: Entirely made of fused silica, ca. 230 mm length
Optical cell heating: Approx. 50° C
Stripping gas: argon (optional nitrogen), 4-6 l/h,stabilized with electronic mass flow controller
Autosampler: 53 place random access, turntable-type
Sample vials: 10 ml, glass; aluminium foil disc covers as accessory
Heating coil temperature: ca. 98° C
Detection limit: < 80 pg Hg
Measuring range: 10 ng/l ... 10 µg/l
Zero drift: Auto zero before each measurement
Measuring duration: Typical 60 Ð 280 seconds
Software: AULA-WIN, WindowsTM based
Electrical power supply: 115 V / 230 V~; 50 - 60 Hz, consumption ca. 100 W
(AULA 254-ASD: 120 W)
Dimensions: Autosampler-reaction unit: 345 x 295 x 330 mm (WxHxD)
Photometer: 450 x 150 x 350 mm (WxHxD)
Bench space requirements: ca. 90 x 70 cm (W x D), excl. PC
Weight: Approx. 14 kg total (excl. PC)
Technical Specifications AULA 254-GoldTrap
Preconcentration principle: Amalgamation on gold surface and subsequent release by quick heating
Measuring range: 1 ng/l Ð 5 µg/l
Detection limit: < 8 pg Hg

As a leading supplier of high precision analytical equipment, we strive at all times to offer top quality solutions. Our products are manufactured according to the ISO 9001 quality regulations.

Ankersmid M&C bvba,  (32) - 3/820 80 01