Automatic Mercury Analyzerfor the Laboratory

AULA 254AULA Fluorescence

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Fully automated mercury analysis systemHigh performance flow analysis techniqueTwo detection methods:The AULA 254 uses Cold Vapor Atomic Absorption Spectrometry (CVAAS)The AULA Fluorescence uses Cold Vapor Atomic Fluorescence Spectrometry (CVAFS)

Widest dynamic linear rangeRobust modular constructionAULAWIN software and PC included

Extending the Capabilities of AULA Systems:● Automated Sample

Digestion (ASD) module● GoldTrap module

for maximum sensitivity

Applications

The AULA 254 and AULA Fluorescence are fully auto-matic analysis systems for determining trace mer-cury levels in a wide range of samples. The AULAsystems are designed to be the right tool for resear-chers and scientists. The instrument automates rou-tine analysis: it tests sample after sample followinga specified procedure exactly. This increases efficien-cy and productivity in your lab.

Typical applications include:

● Environmental chemistry (water and waste water,effluents, waste, sludge, soil)

● Biological samples (food, urine, blood, saliva, hair)

● Chemical industry (process monitoring, quality control)

● Geochemistry (geological and mineralogical samples)

● Petrochemistry (oil products)

● Metallurgy and material testing

Reliable and proven method

The system's working principle is the continuousflow technique. A continuous injection of stannouschloride in the sample flow transforms the mercuryinto elemental mercury. In a special crossflow reac-tor an argon stream strips out the elemental mer-cury and carries it into an optical cell. The mercuryconcentration is quantified in the cell, according tothe AULA system being used:

I: the AULA 254 measures resonance absorption at awavelength of 253.65 nm at ambient temperature.This analytical detection method is commonlyknown as cold vapor atomic absorptionspectrometry (CVAAS).

II: the AULA Fluorescence quanti-fies resonance fluorescence at awavelength of 253.65 nm atambient temperature, a tech-nique known as cold vaporatomic fluorescence spectro-metry (CVAFS).

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Figure: AULA system featuring photometer (left) and autosampler-reaction unit with ASD (right)

Optimized mercury detection technique

AULA 254: Atomic Absorption.Unlike typical multi-elementAA systems, the AULA 254 isspecially designed to detectand quantify mercury levels.This allows top performancein analytical applications. TheAULA 254 uses an electro-opti-cal stabilized electrodelessmercury discharge lamp (EDL)in connection with solid stateUV detectors, resulting in ex-cellent baseline stability anddetection limits far lower thanthose of other AA mercuryanalyzers.

AULA Fluorescence: Atomic Fluorescence. The AULAFluorescence employs the Channel Photomultiplier,a novel type of photomultiplier that can detectsingle photons. In combination with a very lowbackground signal from our optimized low-reflec-tion fluorescence cell, the AULA Fluorescence canreach extremely low (sub-ppt) detection limits.

High productivity

The typical duration of a full measurement cycle is60 ... 180 seconds, depending on the set parameters.Measuring calibration standards, samples and QCstandards is fully automatic. No long purging or rin-sing procedure is needed, even when samples withhigh concentrations are analyzed.

The AULA system is simple to use. Samples are de-canted into glass vials and positioned on the auto-sampler carousel. Reagent solution (tin-(II)-chloride)and rinse solution are filled into the corresponding

bottles.A keystroke starts automatic measu-

rement. The operator can sus-pend the automatic cycle

at any time to selectany sample for mea-

surement or re-measurement.

New samplescan be added atany time, evenduring a sam-ple run.

Minimized memory effects

Mercury vapor tends to cling to surfaces, causing acarry-over (memory effect) that can compromiseresults. AULA systems minimize memory effect byusing selected materials (FEP, borosilicate glass,Tygon LFL) for components touched by samples andby heating the optical bench. In addition, the auto-sampler probe and the sample tubing are rinsedafter each sample run. Even samples with concentra-tions in the upper measuring range do not causecarry-over, allowing a high sample throughput.

MERCURY INSTRUMENTS · ANALYTICAL TECHNOLOGIES

AULA 254-ASD Diagram P

Abb.: AULA-ASD Fließschema

KMnO4

T= 98°C

NH3OHCl

Rinse solution

Drain Argon

Turntable

Rinse pump

Rinse station

SnCl2

Crossflow- reactor

Thermoelectric dehumidifier

Photometer

Figure: AULA-ASD Flow diagram

Chemische Reaktion Carry over effect Comparision

Hydroxyl- Ammoniumchlorid

Zinn-II-Chlorid

KaliumpermanganatSalzsäure

Probe

beheizte Reaktionsschleife

Ausblasstrom zum Photometer

Ablauf

UV-Quelle (EDL)

t

kein Verschleppungseffekt

0,3309

0,0001 0,0001

0,35

0,30

0,25

0,20

0,15

0,10

0,05

0

Mes

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sorp

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1

14,00

Probe Blindwert Blindwert2

<0,01

3

<0,01

Messung Nr.

Hg Konzen- tration (µg/l)

hydroxylamine hydrochloride

tin-II-chloride

potassium permanganate

hydro- chloric

acid

Sample

heated reaction coil

stripping gas to photometer

drain

UV-sourc

Sample D

no carry over effect

0.3309

0.35

0.30

0.25

0.20

0.15

0.10

0.05

0

sign

al a

bsor

banc

e un

its

1

14.00

2

<0.01

3

<0.01

Measure- ment No. Hg concentra- tion (µg/l)

0.0001 0.0001

Sample Blank Blank

Automatic baseline correction

The stability of the baseline is checked prior to eachmeasurement and the zero point is adjusted auto-matically. Typical zero drift during a measurement isbelow 0.0001 absorbance units.

Thermoelectric dehumidifier

Traditional mercury analyzers use desiccant-filleddryer tubes or permeation tubes for removing watervapor from the mercury-loaded carrier gas, andthese tubes add a maintenance burden. The AULAsystem uses a maintenance-free thermoelectricdehumidifier. The gas is cooled below the dew point;excess water condenses on the wall of a small glasstube and flows back into the reactor. In contrast toother dryers this device has an extremely small sur-face, which prevents mercury adsorption.

Carrier gas flow stabilisation withelectronic mass flow controller (MFC)

The stability of the carrier gas flow directly affectsthe reproducibility of measurements. For this reasonthe AULA 254 system uses a highly precise (1% accu-racy) electronic mass flow controller (MFC) which isbuilt into the photometer. The system saves gas byautomatically shutting off flow at the end of thejob.

User safety

The AULA system collects mercury vapor in a sul-furized activated carbon filter, preventing the vaporfrom escaping into the working environment. Amessage appears on the screen if the filter needsreplacement. A fume hood is not required.

Automatic protective system cleaning

The instrument automatically interrupts measure-ment if a sample with a mercury concentrationexceeding the safe range is detected. In this case thesystem immediately performs a cleaning step. Theremaining sample can be diluted and used for asecond run.

Full-feature software

The AULAWIN software offers the complete featureset of modern analytical software. Developed withsubstantial input from our users, it is sur-prisingly easy to use. Samples, calibra-tion standards and quality controlstandards (QCs) are selected bysimple point-and-click. AULA-WIN creates a correspondingsample table automatically,and the user can furtherspecify sample dilutionfactors as well as sampleweight and fill-up volumesfor solid sample digestion.

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Peltierkühler Aufschluß Chemische R

Salzsäur

Probe

Ablauf

Trockenes Trägergas zum Photometer

Thermo- elektrischer

Trockner (Peltier Kühler)

Kondensat

Gas-Flüssigkeits- separator

Trägergas- zufuhr

Probe A Probe B Probe C Probe D

0,10

0,5

1,0

ppb Hg

MikrowellenaufschlussAufschluss mit AULA-ASD

hychloric

Sample

Liquid drain

U

Dry carrier gas to photometer

Thermo- electric

dehumidifier �(Peltier cooler)

Condensed Water

Gas-liquid separator

Carrier gas in

Sample A Sample B Sample C Sample D

0.10

0.5

1.0

ppb Hg

Microwave DigestionAULA-ASD Digestion

Figure: Schematic of gas-liquid separator with thermoelectricdehumidifier

Figure: Screen print of sample table and measurement signal window (1 ppb)

The software makes it easy to measure a samplerepeatedly. The result of each measurement is cal-culated automatically from the chosen calibrationfunction and displayed in µg/l or µg/kg. The QC function assures a high level of reliability. A toolbarallows fast access to frequently used functions.The absorbance signal graph can be viewed in realtime and may also be recalled later.

The analytical results are filed together with all datanecessary for quality assurance (date, time, user ID,sample number, calibration data, method parame-ters, signal graph, and so on). Worksheet templatescan be created and stored to minimize set-up timefor routine work. The user can format report sheetsso that only the required data are printed.

A C C E S S O R I E S

Automated sample digestion (ASD) module

The AULA system can be equipped with a samplepreparation system for aqueous samples. The ASDmodule carries out a digestion procedure derivedfrom standard laboratory methods.

The module automatically draws sample from itsvial and continuously mixes it with an oxidizing

reagent (e.g. potassium permanganate, potas-sium dichromate). The sample/oxidant mixture

is then heated to ca. 98°C in a reaction coil.After the oxidation step hydroxylamine hy-drochloride and tin-(II)-chloride are added toreduce the mercury to an elemental state.

Water samples measured directly with theAULA-ASD module (8 ml of sample + 2 ml

HNO3 + 2 ml H2O2) yield results that closely

match the same water samples digested withmicrowave. Automatic sample digestion is fast:cycle time for a complete analysis is less than 4 minutes.

The AULA-ASD module is economical. Averagereagent consumption for 100 analyses is: 3 g hydro-xylamine hydrochloride, 1-5 g potassium permanga-nate, 6 g tin-(II-chloride, 5 l water (deionized).

The AULA-ASD module is suited to any applicationwhere aqueous solutions require a sample treat-ment prior to analysis: surface water, ground water,seepage water, effluents, process water, and so on.

MERCURY INSTRUMENTS · ANALYTICAL TECHNOLOGIES

Peltierkühler Aufschluß Chemische R

Salzsäure

Probe

Ablauf

Trockenes Trägergas zum Photometer

Thermo- elektrischer

Trockner (Peltier Kühler)

Kondensat

Gas-Flüssigkeits- separator

Trägergas- zufuhr

Probe A Probe B Probe C Probe D

0,10

0,5

1,0

ppb Hg

MikrowellenaufschlussAufschluss mit AULA-ASD

hydro- chloric

acid

Sample

Liquid drain

U

Dry carrier gas to photometer

Thermo- electric

dehumidifier �(Peltier cooler)

Condensed Water

Gas-liquid separator

Carrier gas in

Sample A Sample B Sample C Sample D

0.10

0.5

1.0

ppb Hg

Microwave DigestionAULA-ASD Digestion

Figure: Comparison of microwave digested samples (light blue)and directly with AULA-ASD measured samples (dark blue)

Sample A: seepage water from chlor-alkali plantSample B: tank rinsing water from chlor-alkali plantSample C: effluents from PTFE production plantSample D: sewer plant effluent

Figure: Calibration graph and turntable screen

GoldTrap module

The GoldTrap mercury preconcentration module dra-stically enhances detection sensitivity, to valueslower than 1 ng/l. Using ultra pure reagents and fol-lowing the guidelines for mercury analysis at ultratrace levels, the AULA 254 (using AAS) can achieve a

measuring range from 1ppt to 5000 ppt, and theAULA Fluorescence(using AFS) can achievea measuring range from0.05 ppt to 5000 ppt.

Small thermal inertia is an outstanding property ofour latest GoldTrap design, achieved through theuse of a wafer-thin ceramic substrate. Heating andcooling rates are now very fast. Analysis duration iscomparable to the direct method.

The GoldTrap module is installed inside the photo-meter, thus not increasing footprint space. The usercan select by software if analyses will include aGoldTrap preconcentration step or bypass it. Thismakes the instrument versatile for any application.

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Atomic Absorption versus Atomic Fluorescence: A Comparison

The cold vapor atomic absorption technique is commonly used for mercury trace analysis because of its simplicity, robustness, and relative freedom from interferences. Excellent detection limits can be achieved with modern instruments.

For even lowerdetection limits,users turn to theatomic fluores-cence technique.However, theultra-low limitscan only be rea-ched if extremecare is taken tokeep blanks atlowest levels andcontamination toa minimum. Pre-cautions describedin the appropriatestandard methodsmust be strictlyfollowed.

er effect Comparision

Probe

Atom- fluoreszenz

Atom- absorbtion

Abgas

UV-Quelle (EDL)

t

I

t

I

Si Photodiode

Channel Photomultiplier

kein Verschleppungseffekt

0,0001 0,0001

0,35

0,30

0,25

0,20

0,15

0,10

0,05

0

Blindwert Blindwert2

<0,01

3

<0,01

Messung Nr.

Hg Konzen- tration (µg/l)

sample in

atomic fluorescence

atomic absorbtion

sample out

UV-source (EDL)

t

I

t

I

Si photodiode

channel photomultiplier

no carry over effect

0.35

0.30

0.25

0.20

0.15

0.10

0.05

0

2

<0.01

3

<0.01

Measure- ment No. Hg concentra- tion (µg/l)

0.0001 0.0001

Blank Blank

The AULA system meets current regulations, withcapacity in reserve to meet more stringent stan-dards. Compliant with EPA Method 7470A (liquidwaste), 7471A (solid or semisolid waste), 245.1 (drink-ing, surface, and saline waters, domestic and indus-trial wastes), 245.5 (soils, sediments, bottom depo-sits, and sludge type materials), 245.6, ASTM E538

(caustic soda and potash), ISO 6637 (fruit, vegetablesand derived products), ISO 11212-2 (starch and de-rived products), The Ontario Hydro Method (stackgas), European Method EN 1483 (water quality), EN12497 [AULA 254 only] , EPA Method 245.7 (water),1631 (water). EN 13806 and European Method EN13506 (water) [AULA Fluorescence only]

Technical Specifications AULA 254 and AULA-Fluorescence

Measuring principle: Atomic Absorption, cold vapor technique (CVAAS)Atomic Fluorescence, cold vapor technique (CVAFS)

Analytical wavelength: 253.65 nmUV source: Electrodeless low-pressure mercury discharge lamp (EDL)Stabilization method: Reference beam techniqueDetector: UV enhanced silicon photo diode

Channel photomultiplier, photon count mode Optical cell: Entirely made of fused silica, ca. 230 mm length

Low reflection fluorescence cell Stripping gas: Argon, 4~6 l/h, stabilized with electronic mass flow controller (MFC)Gas-liquid separator: Bubble-free, non-foaming crossflow principle designSample gas dehumidifier: Thermoelectric principle (desiccant-free, low surface area)Reagent / sample pump: 3-channel peristaltic pump, stabilized fixed speed (AULA -ASD: two pumps)Autosampler: 53-place random access, carousel-typeSample vials: 10 ml, glass; aluminium foil disc covers as accessorySample consumption: ca. 1 mlHeating coil temperature (AULA-ASD): ca. 98 °CDetection limit: < 30 pg Hg

< 3 pg HgMeasuring range: 10 ng/L - 50 µg/L (10 ppt – 50 ppb)

0.5 ng/L – 10 µg/L (0.5 ppt – 10 ppb)Zero drift: Autozero before each measurementMeasuring duration: 60 – 180 seconds typicalSoftware: AULA-WIN, WindowsTM basedElectrical power supply: 115 V / 230 V~; 50 - 60 Hz, consumption ca. 100 W

AULA with ASD module: 150 WDimensions: Autosampler-reaction unit: 345 x 295 x 330 mm (WxHxD)

Photometer: 160 x 450 x 360 mmBench space requirements: ca. 90 x 70 cm (W x D), without PCWeight: approx. 14 kg total, without PC

Technical Specifications AULA 254 GoldTrap and AULA Fluorescence GoldTrap

Pre concentration principle: Amalgamation on gold surface and subsequent release by quick heatingDetection limit: < 5 pg Hg

< 0.5 pg HgMeasuring range: 1 ng/L – 5 µg/L (1 ppt – 5 ppb)

0.05 ng/L – 5 µg/L (0.05 ppt – 5 ppb)Other specifications see AULA standard systems above.

Manufactured according to ISO 9001 quality standard!

MERCURY INSTRUMENTS · ANALYTICAL TECHNOLOGIES

Mercury Instruments GmbHAnalytical TechnologiesLiebigstraße 11bD-85757 KarlsfeldTel.: +49 (0)8131 - 50 57 20Fax: +49 (0)8131 - 50 57 22mail@mercury-instruments.de

The Response to an Analytical Challenge:Mercury Instruments.Quantitative trace analysis of mercury has been a challenging task for the analyst until now. We fromMercury Instruments have made it our job to developinstruments for mercury analysis of the highest techni-cal level. The range of applications for our mercury analyzers is unique world-wide.

www.mercury-instruments.de

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