Equipment

Batch experiments

Batch experiments can be used to evaluate the maximum potential of metal release from soils and sediments, e.g. applying DIN 38 414 - S4 bestimmen. By ICP-MS and ICP-OES, respectively the element concentrations in the solutions can be determined.

Equipment

For batch experiments overhead shakers Rotoshake RS12, (Gerhardt, Königswinter, Germany) and ELU (Edmund Bühler, Hechingen, Germany), a centrifuge Multifuge 3L, (Heraeus, Langenselbold, Germany) and a vacuum filtration device (Lippmann Labortechnik, Dresden, Deutschland) are available.

Sample preparation

For batch experiments samples have to be air dried and sieved to < 2mm. (Minimum sample amount: 5.0 g). Replicates are highly recommended.

Implementation

Bestimmung der Eluierbarkeit mit Wasser nach DIN 38 414 – S4pdf, 20 kb · de (April 2017)

Working material

• air-dried substrate samples (fine soil <2mm)
• balance (accuracy min. 0.01 g)
• HDPE bottles 1 l
• ultrapure water (ThermoScientific "GenPure UV-TOC")
• Centrifuge ("Multifuge 3L, Fa. Heraeus) including 50ml centrifuge tubes (Fa. Greiner, material PP)
• overhead shaker (Rotoshake RS12, Gerhardt)
• conc. HNO3 (65%) (subboiled or suprapur)
• disposable syringes (e.g. 20 ml)
• Membrane filter (syringe filter) 0.45 µm (Sartorius, Minisart, cellulose acetate, No. 16555Q)
• pH/el. Conductivity meters (pH gel electrode instead of electrode with KCl filling to avoid KCl contamination) including calibration solutions (Fa. WTW)
• 15 ml tubes (Greiner, PP material)

Procedure

(As an alternative to the specified amount of 90 g water and 900 g substrate, it is also possible to work with a correspondingly lower sample weight at the same solids-to-liquid ratio in order to keep the time required by several passes low due to the load limit of the shaker when processing several samples simultaneously). 

1. Of each of the air-dried substrate samples, 90 g is weighed twice to the nearest 0.01 g and placed in a 1-liter HDPE bottle.
2. 900 ml of ultrapure water is filled into the HDPE bottle. For a comparison sample (blank sample), one bottle is filled with 900 ml ultrapure water only (without substrate).
3. The pH value and electrical conductivity are measured in all bottles.
4. The bottles are shaken for 24 h in an overhead shaker at 10 to 20 rpm. The sample should remain in motion, further crushing and abrasion should be avoided.
5. The next day, the bottles are removed from the shaker and allowed to sediment the suspension for 15 min.
6. All bottles are again characterized physicochemically: Measurement of pH, electrical conductivity.
7. Now 50 ml of the supernatant of each bottle is carefully transferred into a 50 ml centrifuge tube.
8. The tubes are centrifuged in the centrifuge for 10 min at 4000 rpm.
9. The supernatant is transferred to a beaker in each case and divided between two 15 ml tubes as follo
   
   • Cation analysis: Draw up sample in syringe and filter through 0.45 µm filter unit (discard the first drops!) and add 3 drops of conc. HNO3.
   • Anion analysis: Draw up sample in syringe and filter through 0.45 µm filter unit (discard the first drops!) (WITHOUT addition of acid

Sequential extraction

Sequential extraction according to Zeien & Brümmer can be applied to differentiate heavy metals according to mobility and and chemical bonding for soils with minor carbonate contents.

Equipment

For sequential extractions according to Zeien & Brümmer overhead shakers Rotoshake RS12, (Gerhardt, Königswinter, Germany) and ELU (Edmund Bühler, Hechingen, Germany), a centrifuge Multifuge 3L, (Heraeus, Langenselbold, Germany) and a vacuum filtration device (Lippmann Labortechnik, Dresden, Germany) are available.

Sample preparation

For sequential extractions according to Zeien & Brümmer samples have to be air dried and sieved to < 2mm (Minimum sample amount: 2.0 g, 5 g are recommended).

Used devices and materials

Devices

• Centrifuge: "Multifuge 3L, Heraeus company
• Centrifuge tubes: 15 ml und 50 ml, material PP, Fa. Greiner
• Overhead shaker: Rotoshake RS12, Gerhardt Company
• Vacuum filtration apparatus: Lippmann-Labortechnik Dresden, Germany
• Dispensettes: BRAND
• Analytical balance: Sartorius BP210S
• Ultrapure water system: ThermoScientific 2GenPure "UV-TOC
• Sample bottles: acid rinsed with diluted HNO3, 100 ml, material PP, Fa. Kautex resp. VWR
• Membrane filter: cellulose acetate (Sartorius 11106-47, 0.45 µm)

Chemicals

(if not specified otherwise, then purity "for analysis" p.a.)

• Ammonium nitrate NH4NO3 (Fa. Roth, No. K299.1)
• Ammonium acetate CH3COONH4 (NH4OAc) (Merck, No. 101116)
• Hydroxylammonium chloride NH2OH * HCl (Merck, No. 104619)
• Titriplex II C10H16N2O8 (edetic acid, EDTA, Merck, No. 108417)
• di-ammonium oxalate monohydrate C2H8N2O4 * H2O (Merck, No. 101192)
• oxalic acid dihydrate C2H2O4 * 2 H2O (Merck, No. 100495)
• L(+)-ascorbic acid (vitamin C) (Merck, No. 100127)
• Acetic acid C2H4O2 50% (diluted from glacial acetic acid, Merck No. 100063)
• Ammonia solution NH3 25% (Merck 105432)
• Nitric acid HNO3 65% subboiled (Fa. Merck: 100456, purified by subboiling distillation)
• Hydrochloric acid HCl fuming 37% (Fa. Roth)
• Ultrapure water "ThermoScientific 2GenPure" UV-TOC)

Working instruction

Fraction I: Mobile heavy metals

• Weighing: 2 g to the nearest 0.01 g of air-dried fine soil (<2 mm) in centrifuge tubes (50 ml)
• Extracting agent: 50 ml 1 M NH4NO3 (NH4NO3: 80.04 g/l, Fa. Roth, No. K299.1)
• Shaking time: 24 h at 20°C and approx. 20 rpm (overhead shaker)
• extraction solution recovery: centrifuge at 2500 rpm for 15 min
• Transfer supernatant solution through cellulose acetate filter by vacuum filtration apparatus into acid-rinsed bottles
• Stabilize the filtrates by adding 0.5 ml HNO3 (65%)

Fraction II: Easily deliverable heavy metals

• Add 50 ml of 1 M NH4OAc (pH 6.0) to the sample remaining in the centrifuge beaker (CH3COONH4 (NH4OAc) : 77.08 g/l, Merck, No. 101116, adjusted to pH 6.0 with 50% acetic acid).
• For soil samples containing carbonates (> 5% CaCO3), add the appropriate amount of diluted HCl p.a. to neutralize the carbonates (to ensure pH constancy of pH 6.0).
• Shake for 24 h
• centrifuge for 15 min at 2500 rpm
  • Transfer supernatant solution via cellulose acetate filter by vacuum filtration apparatus into acid-rinsed bottles
  • Recovery of the residual solution remaining in the soil sample: shake sample with 25 ml 1 M NH4NO3 (solution fraction I) for 10 min, centrifuge and filter (the filtrates are combined)
  • Stabilize the filtrates by adding 0.5 ml HNO3 (65%).

 

Fraction III: Heavy metals bound to Mn oxides

• Add 50 ml 0.1 M NH2OH-HCl + 1 M NH4OAc (pH 6.0) to the sample remaining in the centrifuge beaker (NH2OH-HCl: 6.95 g/l, Merck, No. 104619 and NH4OAc: 77.08 g/l, Merck No. 1116; adjusted to pH 6.0 with diluted HCl)
• shake for 30 min
• centrifuge at 2500 rpm for 15 min
  • Transfer supernatant solution via cellulose-acetate filter by vacuum filtration into acid-rinsed bottles
  • Recovery of the residual solution remaining in the soil sample: Add 25 ml of 1 M CH3COONH4 (NH4OAc) (pH 6.0) (solution fraction II) to the sample twice and shake, centrifuge and filter for 10 min each time (the filtrates are combined)
  • Stabilize the filtrates by adding 0.5 ml HCl (37%).

 

Fraction IV: Heavy metals bound to organic substances

• Add 50 ml 0.025 M NH4-EDTA (pH 4.6) to the sample remaining in the centrifuge beaker (Editin acid: 7.31 g/l, Titriplex II, Merck, No. 108417, adjusted to pH 4.6 with diluted ammonia solution)
• 90 min shaking
• centrifuge for 15 min at 2500 rpm
  • Transfer supernatant solution via cellulose-acetate filter by vacuum filtration into acid-rinsed bottles
  • Obtain the residual solution remaining in the soil sample: add 25 ml of 1 M NH4OAc (pH 4.6) to the sample (NH4OAc : 77.08 g/l, Merck, No. 101116, adjusted to pH 4.6 with 50% acetic acid (Merck, No. 63)), shake for 10 min, centrifuge and filter (the filtrates are combined)

Fraction V: Heavy metals bound to poorly crystalline Fe oxides.

• Add 50 ml of 0.2 M NH4 oxalate (pH 3.25) to the sample remaining in the centrifuge beaker (di-ammonium oxalate monohydrate: 28.422 g/l, Merck, No. 101192 and oxalic acid dihydrate: 25.214 g/l, Merck, No. 100495), adjusted to pH 3.25 with diluted ammonia solution)
• Shake for 4 h in the dark
• centrifuge for 15 min at 2500 rpm
  • Transfer supernatant solution via cellulose-acetate filter by vacuum filtration into acid-rinsed bottles
  • Obtain the residual solution remaining in the soil sample: add 25 ml of 0.2 M NH4 oxalate (pH 3.25) to the sample once (solution fraction V), shake for 10 min in the dark, centrifuge and filter (the filtrates are combined)

Fraction VI: Heavy metals bound to crystalline Fe oxides

• Add 50 ml of 0.1 M ascorbic acid and 0.2 M NH4-oxalate (pH 3.25) to the sample remaining in the centrifuge beaker (0.1 M L(+)-ascorbic acid (vitamin C): 17.613 g/l, Merck, No. 100127 + 0.2 M NH4-oxalate buffer: 0.2 M di-ammonium oxalate monohydrate p.a.: 28.422 g/l; Fa. Merck, No. 101192 and 0.2 M oxalic acid dihydrate p.a.: 25.214 g/l; Merck, No. 100495), adjusted to pH 3.25 with diluted ammonia solution).
• extract for 30 min in a water bath at 96 +- 3°C
• centrifuge at 2500 rpm for 15 min
  • Transfer supernatant solution via cellulose-acetate filter by vacuum filtration system into acid-rinsed bottles
  • Obtain the residual solution remaining in the soil sample: add 25 ml of 0.2 M NH4 oxalate (pH 3.25) (solution fraction V) to the sample once, shake for 10 min in the dark, centrifuge and filter (the filtrates are combined)

More info

Excerpt from: Lewandowski, Jörg: Pollutants in soil: an introduction to analysis and evaluation; Springer 1997, ISBN: 3-540-62643-3, p. 129-130.

"In a sequential extraction, the weakest bound heavy metals are first dissolved with the weakest solvent. Then (sequentially), on the same soil sample, a stronger solvent is used to capture the next fraction of heavy metals that are somewhat more tightly bound.

Finally, over several stages, the strongest solvent is used to dissolve the most strongly bound heavy metals, and thus the total content is determined. This means that an extraction agent ideally dissolves only one heavy metal fraction, because the more lightly bound heavy metals have already been separated.

For ecological questions, not only the total content of heavy metals in the soil is interesting, but above all the ecological availability. Depending on the binding form, the heavy metals are either immediately available, mobilizable in the short term, releasable in the long term, or immobile. The mobilization of heavy metals is determined by chemical-physical soil parameters.

With sequential extraction "an attempt is made to record the heavy metals separately according to their bonding forms" by increasing the strength of the extraction agents. This is intended to provide information on the ecological availability of the heavy metals. (Federer 1993, p. 21)"

Microwave digestion

By means of microwave digestion the digestion of biological materials (plants, microorganisms) and the digestion of geological samples (by aqua regia) is possible. By ICP-MS and ICP-OES, respectively the element concentrations in the digestion solutions can be determined.

Equipment

Mars Xpress-System (CEM, Kamp-Lintfort, Germany) for simultaneous microwave assisted pressure digestion of up to 40 samples. Vessels made of PFA are available featuring volumes of 10 mL, 55 mL, 100 mL.

Sample preparation

For microwave digestion samples must be dried and ground (minimum mass: 500 mg; if less material is available please discuss in advance). We suggest to ground larger masses to guarantee highest possible representativity of the sample.

For biological samples a clear indication is necessary if the sample contains toxic/pathogenic microorgansims.

Used equipment and materials

(April 2017)

• Microwave: "MARS 5 Xpress" (MARS = Microwave Activated Reaction System) from CEM GmbH, Kamp-Lintfort.
• Digestion vessels: "Xpress", material: PFA, volume: 10 ml and 55 ml, CEM GmbH HP 500 Plus, material: PFA, volume: 100 ml, CEM GmbH
• Analytical balance: Sartorius BP210S
• Dosing device acid: "Dispensette", Brand, Wertheim, Germany
• Centrifuge: "Multifuge 3L", Heraeus company
• Ultrapure water system: ThermoScientific "GenPure UV-TOC
• Disposable weighing dish: Material: PS, VWR, Darmstadt
• Volumetric flasks: 10 ml, 25 ml, 50 ml, material: PMP, class A, Fa. Vitlab
• Centrifuge tubes: 15 ml, 50 ml, material: PP, Fa. Greiner
• Funnels: material: PP, Fa. Kartell
• Sample bottles: acid rinsed with diluted HNO3, Nalgene HDPE, 30 ml

Only "ultrapure water" and chemicals/acids of the purity "suprapur" or "subboiled" are used!

Digestion programs

(Status: April 2017)
Microwave power operates adjusted from 0-1600 watts depending on the program and the number of containers used.

Program "Plants Xpress - XPRESS" for organic material (plants, microbes).

Container: Xpress, 55 ml
Typical sample weight: ~ 0.2 g
Acid addition: 5 ml HNO3 65%
Pre-reaction in open container: approx. 20 min.

Time ramp temperature
Heating up to 180°C: 15 min.
Holding at 180°C: 15 min.
Cooling down: 30 min.

Transfer finished digestion by funnel into 25 ml volumetric flask and fill up with ultrapure water. Transfer to 50 ml centrifuge tubes and centrifuge at 3000 rpm. Centrifuge for 15 min. to separate any undissolved components, e.g. silicates. Transfer the clear supernatant into acid-rinsed bottles.

 

Program "Königswasser" (for e.g. soil, dust samples)

largely according to DIN 13346: "Characterization of sludges, determination of trace elements and phosphorus, extraction method with aqua regia, German version EN 13346:2000".

Container: HP 500 plus, 100 ml
Typical sample weight: ~ 0.5 g
Acid addition: 2 ml HNO3 65% + 6 ml HCl 35% ("Königswasser")
Pre-reaction in open vessel: approx. 20 min.

Time ramp temperature
Heating up to 160°C: 15 min.
Holding at 160°C: 20 min.
Cooling down: 30 min.

Transfer finished digestion by funnel into 50 ml volumetric flask and fill up with ultrapure water. Transfer to 50 ml centrifuge tubes and centrifuge at 3000 rpm. Centrifuge for 15 min. to separate undissolved components, e.g. silicates. Transfer the clear supernatant into acid-rinsed bottles.

Program "Königswasser" (for e.g. spider's web, filter samples)

largely according to DIN EN 16174: "Sludge, treated biowaste and soil - Digestion of aqua regia soluble fractions of elements; German version EN 16174:2012".

Container: HP 500 plus, 100 ml
Typical sample weight: ~ 0.5 g (often much less in the case of spider's web)
Acid addition: 2 ml HNO3 65% + 6 ml HCl 35% ("Königswasser")
Pre-reaction in open vessel: approx. 20 min.

Time ramp temperature
Heating up to 175°C: 15 min.
Holding at 175°C: 20 min.
Cooling down: 30 min.

Transfer finished digestion by funnel into 25 ml volumetric flask and fill up with ultrapure water. Transfer to 50 ml centrifuge tubes and centrifuge at 3000 rpm. Centrifuge for 15 min. to separate undissolved components, e.g. silicates. Transfer the clear supernatant into acid-rinsed bottles.

Further Infos

Slightly modified excerpt from:

www.cem.deExternal link

 "Microwave pressure digestion systems", in contrast to digestion systems with convective heating, are able to dissolve the solid sample within a much shorter time.

This time advantage is achieved by direct heating of the digestion solution by microwaves, rapid cooling after digestion has taken place and the attainment of digestion temperatures far above the "normal" boiling point of the digestion acids.

Microwave heating represents a special case of heating. In contrast to convective heating, in which the amount of heat is supplied to the material from the outside and distributed within the material by its thermal conductivity (surface heating), in microwave heating the heat is generated in the material itself (volume heating).

Despite the term "pressure digestion", pressure is not an essential criterion in the digestion process. In fact, the pressure that builds up during the digestion reaction is more of an annoying side effect that must be compensated for by sophisticated vessel technology and measurement and control equipment. This digestion technique is better characterized as a "wet digestion method using dissolving and/or oxidizing digestion reagents in a closed system". The decisive criterion for digestion is the temperature at which the acids cause digestion of the sample. The pressure mainly occurs during decomposition, i.e. oxidation of organic material to CO2 and H2O, and thus limits the sample quantity.

In the digestion of inorganic materials, the resulting pressure plays only a minor role.

Further info: www.cem.deExternal link

Total digestion system

With this system the complete digestion of geological samples is possible by means of HF / HClO₄. By ICP-MS and ICP-OES, respectively the element concentrations in the digestion solutions can be determined.

Equipment

Total digestion system DAS (PicoTrace, Bovenden, Germany) for the simultaneous digestion of up to 32 samples. Vessels made from PTFE-TFM are available for the addition of up to 10 mL of acids.

Sample preparation

For total digestion samples must be dried and ground (minimum mass: 500 mg; if less material is available please discuss in advance). We suggest to ground larger masses to guarantee highest possible representativity of the sample.

Details

(modified from Grawunder et al., 2014External link):

100-150 mg of each ground sample were digested in a pressure digestion system (DAS, PicoTrace). The ground material was put in TFM vessels and 2 mL 65% HNO₃ (subboiled), 3 mL 40% HF and 3 mL 70% HClO₄ (both suprapur, Merck) were added. This mixture was then heated up to 180°C within 6 h. After maintaining the temperature for 12 h the samples were cooled down. For evaporating the acids, the system was heated up again to 180 °C for 4-5 h in a special evaporating hood maintaining the temperature again for 14 h. The remaining solids were dissolved again after adding 2 mL HNO₃ (p.A. Merck, subboiled), 0.6 mL HCl (suprapur, Roth) and 7 mL pure water (GenPure UV-TOC, Thermo Fisher Scientific) at 150°C within 8 h. The cooled samples were transferred to calibrated 25 mL flasks (PMP, Vitlab) and replenished to 25 mL by addition of pure water.

Inductively coupled plasma mass spectrometry (ICP-MS)

ICP-MS can be applied to the determination of metals and metalloids in trace and ultra-trace concentrations in aqueous solutions or via coupling to laser ablation also directly in solid samples.

Equipment

Supported by the German Research Foundation (FKZ INST 275/441-1 FUGGExternal link).

8900 Triple Quadrupole ICP-MS (FA. Agilent, Waldbronn, Germany)

• For feeding of liquid samples an autosampler (prepFAST2DX System, Fa. Elemental Scientific, Mainz, Germany) is available.
  
  
• For the direct analysis of solid samples a 213 nm Nd:YAG laser ablation system LSX-213 G2+ (Teledyne CETAC Technologies, Omaha, USA) can be coupled. It is equipped with a HelEx II Active 2-Volume Cell (Teledyne CETAC Technologies, Omaha, USA) that can be used either with a sample drawer with open geometry (9.4 x 9.0 x 1.5 cm) or with a customized drawer for cores (2.5 cm diameter) or slides/thin sections (max. 2.4 x 10.0 cm). A number of reference materials for both geological and biological sample materials is available. Further information on this is available upon request.

Until 2020: Quadrupol-ICP-MS-Spektrometer XSeries II (Fa. Thermo Scientific, Bremen, Germany) 

• For feeding of liquid samples an autosampler ASX 520 (Fa. Teledyne CETAC, Omaha, USA) was available.

Sample preparation

Liquid samples (a volume of at least 5 mL is required, if less volume is available please contact Dirk Merten in advance) must be free of particles (filtration < 0.45μm or suitable centrifugation).

Subsequent to filtration samples must be acidified to pH<2 using HNO3. Samples must delivered with a list of electrical conductivities prior to acidification. If samples originate from extractions or the digestion of solid samples the used weight of the solid samples and the volume, concentration and kind of extracting solutions have to be delivered.

Sample preparation of solid samples for the analysis by LA-ICP-MS depends on the particular sample material and has to be discussed in advance.

Quality Assurance

Calibration is performed using multi element calibratrion solutions having concentrations of 0, 1, 5, 10, 50 respectively 100 μg/L of echa of the elements to be analysed. For details please see heredocx, 14 kb · de

Accuracy of the measurements is verified using standard reference materials:

• SPS-SW 2PDF, 77 kb
• NIST1643fpdf, 72 kb
• TM-25.5pdf, 160 kb
• SCREE1External link
• PPREE1External link

20 μg/L Ru and 10 μg/L Re are added as internal standards to all blanks, calbration standards, refrence materials and samples for drift corection. Alle solutions have a final concnetration of at least 2% HNO₃

Samples will be diluted to a total dissolved solids below 1 g/L according to their matrix or their elctrical conductivity for water samples, respectively.

For each sample three replicate measurements are performed, an outlier test according to Grubbs (sgnificance 90%) is carried out and subsequently mean and the single absolute standard deviation are calculated and reported with the results.

The detection limit is calculated for each measurement based on the 3 σ crteroin, taking the dilution of the sample into account. Detection limist are reported with the results if concentration of one or more of the elements in below the respective detection limit.

Contact

For liquid measurements and solid samples: Dirk Merten (Laboratory management)

For solid samples: Annemie Kusturica

Optical emission spectrometry inductively coupled optical emission spectrometry (ICP-OES)

ICP-OES can be applied to the determination of metals and metalloids in major, minor and trace concentrations in aqueous solutions.

Equipment

Simultaneous radial ICP-OES spectrometer 725ES (Agilent, Waldbronn, Germany) with CCD-detector. For feeding of liquid samples an autosampler ASX 520 (Fa. Teledyne CETAC, Omaha, USA) is available.

Sample preparation

Liquid samples (a volume of at least 10 mL is required, (if less volume is available please contact (link Merten) in advance) must be free of particles (filtration < 0.45μm or suitable centrifugation).

Subsequent to filtration samples must be acidified to pH<2 using HNO₃. Samples must delivered with a list of electrical conductivities prior to acidification. If samples originate from extractions or the digestion of solid samples the used weight of the solid samples and the volume, concentration and kind of extracting solutions have to be delivered.

Quality assurance

Details on quality assurance in ICP-OES can be found here

Contact

Dirk Merten (Laboratory management)

Ines Kamp

Ion chromatography (IC)

Ion chromatography can be applied to determine the anions F^-, Cl^-, Br^-, I^-, SO₄^2-, NO₃^-, NO₃^-, and PO₄^3- ranging from main element to trace element concentration in water samples.

Equipment

Ion chromatography system Integrion-RFIC (ThermoFisher Scientific) with Autosampler AS-AP, Eluent generator, Conductivity detector Integrion CD with Supressor ADRS 500, and UV/VIS detector VWD-IC

Anion separation columns IonPac AS18-Fast-4µm with precolumn, respectively IonPac AS11-HC 4µm with precolumn are available; KOH (gradient) is used as eluent.

An integrated automated sample preparation removes alkaline, alkaline earth and transition elements as well as organic impurities (InGuard Na/HRP and enrichment column IonPac UTAC-LP2).

Note

Until March 2018 the following system was used:
Ion chromatography system DX-120 (Thermo Fisher Dionex, Idstein, Germany) with Autosampler AS40 and separation column AS14.

For sepraration of humic substances disposible columns OnGuard P are available while for matrix separation of von Cl^-, Br^-, I^- disposible columns OnGuard II Ag/H can be used.

Sample preparation

Liquid samples (a volume of at least 5 mL is required, (if less volume is available please contact Dirk Merten in advance) must be free of particles (filtration < 0.45μm or suitable centrifugation).

Samples must delivered with a list of electrical conductivities. If samples originate from extractions or the digestion of solid samples the used weight of the solid samples and the volume, concentration and kind of extracting solutions have to be delivered.

Kontakt

Dirk Merten (Laboratory management)

Gerit Weinzierl

Photometry

Photometry can be applied to determine NH₄⁺, NO₂^-, NO₃^-, PO₄^3-, SO₄^2-, Fe GESAMT, Fe ²⁺ in water samples.

Equipment

UV-Spectrophotometers DR4000U and DR6000 (Hach Lange, Düsseldorf, Germany.

Sample preparation

Liquid samples (a volume of at least 50 mL is required, (if less volume is available please contact Dirk Merten in advance) must be free of particles (filtration < 0.45μm or suitable centrifugation).

Samples must delivered with a list of electrical conductivities.

Contact

Dirk Merten (Laboratory management)

Gerit Weinzierl

Titration

Titration can be applied to determine HCO₃^- and CO₃^2- and also hardness in water.

Equipment

• Titration system Titrino 716 DM (Metrohm, Germany) for the determination of HCO₃^- and CO₃^2- in water
• Digital burette Solarus (Hirschmann, Germany) for the determination of water hardness

Sample preparation

A sample volume of at least 100 ml water is required for the determination of HCO₃^- and CO₃^2- (if less volume is available please contact Dirk Merten in advance). For the determination of hardness of water up to 100 ml of water are necessary (depending on the origin of the water).

It is not necessary to filtrate samples and acidification of samples is not permitted.

 

Kontakt

Dirk Merten (Laboratory management)

Ines Kamp

Liquid chromatography – Organic Carbon Detection – Organic Nitrogen Detection (LC-OCD-OND)

The LC-OCD-OND-system can be used for the highly sensitive quantitative detection of organic carbon and organic nitrogen compounds as well as nitrate or ammonium in liquid samples. Natural organic matter is separated into specific fractions such as biopolymers, humic substances, building blocks, low-molecular-weight (LMW) acids, LMW neutrals and hydrophobic compounds. The detection limit is in the low ppb range for organic C and N.

Equipment

• Liquid chromatography system with organic carbon, organic nitrogen and UV detector (Model 9; DOC-Labor Dr. Huber).
• The chromatographic column is filled with a polymer based on polyacrylate (Toyopearl TSK HW50S).
• An Autosampler (MLE Dresden) is available for feeding of liquid samples.
• The system is equipped with a non-dispersive infrared detector (ABB), an UV detector (Knauer; wavelength 254 nm) and an organic nitrogen detector (Knauer; wavelength 220 nm).

Sample preparation

• A sample volume of at least 5 ml is required for each measurement (the use of lower sample volumes might be possible depending on the DOC content but must be discussed in advance).
• Samples can be delivered in glass vials or PP-tubes.
• During sampling and sample preparation, keep sample away from perfume, organic solvents, felt pens etc.
• Do not acidify samples and indicate pH of sample (only samples with a pH of 3-9 can be measured).
•  If TOC/DOC content of sample is known, please submit the information prior to the measurement of the samples.
• Pre-filtration of samples is generally not necessary, as they are routinely filtered in-line with a 0.45 µm filter (PES-membrane). In-line filtration with different pore sizes or measurement of completely unfiltered samples is possible in theory but must be discussed in advance.

Kontakt

Dirk Merten (Laboratory management)

Dr. Sarah Nettemann

NTA

Nanoparticle Tracking Analysis (NTA) with fluorescence option (fluo-NTA)

The investigation of particle size distribution and concentration of natural or artificial nanoparticulate phases in different fluids, e.g. pore waters, ground waters or additives to cements like superplasticizers, is of high importance for the understanding and control of several processes.

With NTA the determination of number weighted sphere-equivalent hydrodynamic diameters of nanoparticulate phases with a certain dn/dc is possible in different fluids in the size range of a few tens of nanometers up to 1-2µm under controlled conditions.

In a dark field microscope, particles get visible through the scattering of light at particles. A video (approx. 25 fps) of particles, which move due to Brownian behavior, is recorded with a SCMOS camera and particles are tracked from frame to frame. Their diffusion coefficient is measured by evaluating their displacement and the resulting hydrodynamic diameter is determined by Stokes-Einstein law.

 

Equipment

A Malvern Nanosight NS300 Nanoparticle Tracking Analysis (NTA) equipped with a 405nm laser and a syringe pump is used for the measurement of single particle size distributions and concentrations in a wide range of fluids.

Nanoparticles/colloids can be measured under static or dynamic flow conditions.

Selectively dyed particles can be measured through the usage of suitable fluorescence dyes and a bandpass (490-550 nm) or a longpass (>715nm) filter.

Sample volumes of ≥ 1ml can be measured in an O-ring-top-plate; a low volume flow cell is available for sample volumes ≤ 1ml.

 

Sample preparation

Generally, for the exact determination of measuring conditions an agreement is necessary.

Liquid samples are measured with a minimum sample volume of 1-2 ml, whereas smaller sample volumes are possible with a prior arrangement.

The specific sample preparation depends on sample origin and sample matrix, due to individual necessity of e.g. filtration and/or dilution.

A constraint to ideal measurement conditions in environmental samples are motile microorganisms, which need to be killed through suitable methods.

Suitable fluorescence dyes need to be chosen for measuring in fluorescence mode.

 

Kontakt

Dirk Merten (Laborleitung)

Ruth Ewouame

3D x-ray microscopy (XRM)

3D x-ray microscopy achieves non-destructive characterisation of 3D microstructures of porous rocks in controlled environments and over time (4D). The Xradia 620 Versa uses a two-stage magnification architecture combining geometrical magnification by conventional microCT and optical magnification by microscope optics before acquisition by a CCD detector. This two-stage magnification enables submicron resolution tomographies across a diverse set of sample sizes and working distances. The XRM has a true spatial resolution of 500 nm with a minimum achievable voxel size of 40 nm. The resolution is still 1.0 µm at a working distance of 50 mm. The XRM records a series of 2D projection radiographs from various angles as well as a reference image (averaged blank image without sample) to reconstruct this stacked 2D projections to a 3D data set.

The data is processed with special visualisation and analysation software. The image processing includes usually adjustments of brightness, contrast and grey scale distribution as well as the filtering of the 3D data set. Visualisation is used to display relevant features of the sample in 2D cross-sections or as 3D volumes. Modification on the grey scale image could be clipping and colouring of the area of interest as well as adjustments in lightning, surface appearances and transparency.

The analysis of the processed image data provides different parameters, which are used for a characterisation of the sample material: e.g. particle sizes, particle forms, pore sizes and their distribution, connected and non-connected porosity, pore fillings, specific surfaces as well as lengths, volume and structures of agglomerates and cracks.

Equipment

High resolution 3D x-ray beam imaging system Xradia Versa 620

• objective lenses 0,4X, 4X, 20X, 40X and flat panel extension (Imaging of larger samples)
• 12 standard filters
• Deben CT5000-TEC, In situ heating/cooling/tensile/compression module, maximum stress 5 kN
• analyse workstation with DragonflyPro

Sample preparation

Porous materials up to a maximum sample height of 30 cm and a maximum weight of 15 kg can be examined in the XRM. The absorption of the x-rays increases with increasing thickness and density of the sample, which is leading to a darker image. Cylindrical sample are ideal for artefact-free measurements as they are rotated centrically during the measurement. Due to the proportionality between sample size and and true spatial resolution it applies: the smaller pore geometry the higher the achievable resolution with same sample material composition. Samples must be delivered with a short description of the material.

Contact

Michael Ude

Dr. Sarah Hupfer

VisiSens

The precise monitoring of pH, O₂ and CO₂ as boundary conditions of experiments or system reactions plays an important role in many disciplines. Measurements with a high spatial resolution offer many advantages over the use of electrode-based methods. By using the VisiSensTD System, fluorescence intensities of planar chemical-optical sensor foils for pH, O₂ and CO₂ can be simultaneously measured in a variety of sample media. Sensor foils with a flexible geometry and sizes up to several cm² are feasible as well as resolutions for data acquisition can be achieved in sub-mm² range. The temporal resolution depends on the operator’s desired measurement frequency.

Equipment

VisiSens TD Camera/Sensor-System with integrated LED for the measurement of pH, O₂ and CO₂.

VisiSens TD Big Area Imaging Kit for exciting sensor foils from larger distances, if camera LED is insufficient for excitement (currently under use in experiment).

 

Sample preparation

An individual preparation and agreement are necessary before operating the system. Furthermore, a calibration customized to the experimental design needs to be conducted. Sensor foils are ordered according to demand and can be customized depending on the requirement.

 

Kontakt

Dirk Merten (Laboratory management)

Marcus Böhm

Magnetic Susceptibilty and Temp-Sus-System

Field measurements for mapping near-surface rocks or soils and lab measurements of cores, rock fragments and powders are possible. The physical parameter magnetic susceptibility is usually dominated by the content of magnetite in a rock.

Equipment

Bartington MS2 susceptibility meter with sensors C, D, D, F for measurements of magnetic volume-specific or with sensor B of mass-specific magnetic susceptibility. Field measurements for mapping near-surface rocks or soils and lab measurements of cores, rock fragments and powders are possible. The physical parameter magnetic susceptibility is usually dominated by the content of magnetite in a rock.

Bartington temperature-susceptibility system with oven MS2WF, water jacketed sensor MS2W and MS2WFP power supply for determination of Curie temperature to characterize ferri- and paramagnetic minerals as e.g. magnetite, hematite, pyrite. Especially the oxygen and titanium content of a melt determine Curie temperatures of a rock. 

Sample preparation

Field measurements for mapping near-surface rocks or soils and lab measurements of cores, rock fragments and powders are possible.

 

Kontakt

Dr. Michael Pirrung (Head of laboratory)

Michael Ude

Wasser

Water

Contact/lending: Michael Ude

• 2"- Water pump Grundfos MP1 (groundwater pumping)
• soil hydrological measurement station (temperature, soil moisture, tension) (see Fig.1 - Fig.2)
• lysimeter station (see Fig.3 - Fig.5)

Contact/lending: Gerit Weinzierl, 948653

• WTW-measuring instruments for physico-chemical parameters (pH, electrical conductivity, redox potential, O2)
• various light plummets
• discharge meter (FlowMate)

Soil/rock

Contact/Lending: Michael Pirrung, 948644

• drilling devices:
  
  
  • Motor Hammer Atlas Cobra 248 for probes
  • slotted probe Ø 32 mm
  • RAM core probe Ø 36 mm
  • Ø 50 mm
  • Hand drill Ø 50 mm
  • Pürckhauer hand drilling sticks
• 10 tons pole hydraulic system
• corer for SEA drilling: modified lower tab MONDSEE-Corer, Ø 60 mm, manual winch

 

Climate station

Contact: Dr. Sarah Nettemann, 948667

• climate Station (THIES GmbH)