Laboratory

The automatic Hg analyser eliminates the sample preparation phase. With this instrument, it is no longer necessary to mineralise the sample beforehand, but it can be analysed directly as is, for a wide range of matrices (soils, sediments, plants, animal tissues, hair, etc.). The DMA-80 is based on atomic absorption spectrophotometry and is equipped with a double cell with a sensitivity range of 0.005 to 1200 ng. In other words, it is possible to analyse solid samples in which the Hg concentration varies from ppb to ppm, without any need for dilution. The instrument operates in full compliance with US-EPA method 7473 and combines several steps: thermal decomposition of the sample, catalytic conversion leading to Hg reduction, formation of Hg0 vapour amalgam with gold, and atomic absorption spectrophotometry.

This device allows real-time measurement of elemental Hg concentrations in the air (response time = 1 sec) using atomic absorption spectrophotometry with high-frequency modulated light polarisation and Zeeman correction (ZAAS-HFM), which is necessary to eliminate possible interference from impurities such as water vapour. The instrument can be used to measure Hg concentrations both outdoors and indoors between 2 and 200,000 ng/m3 and complies with the requirements of EN 15852:2010.
The combined use of the analyser and a specific pyrolysator (PYRO-915+) also allows the Hg content of environmental matrices to be determined using the thermal desorption technique with a lod of 0.5 μg/kg Hg (for rocks and sediments). In addition, thanks to the possibility of gradually heating the sample, it is possible to perform speciation by discriminating between the different Hg compounds present in the sample based on their specific metal release temperatures.
The purchase of these two analytical instruments was partially funded by the Beneficentia Stiftung Foundation.

This is the essential instrument for determining mercury in water samples and, in general, aqueous solutions with concentrations in the ppt range. It uses atomic fluorescence spectrophotometry coupled with Hg reduction using the cold vapour technique (CV-AFS) with or without gold amalgam. The operating principle is based on the standardised EPA Method 1631e. The instrument's limit of detection (LOD) is < 0.1 ng/L.

This is an automated instrument for analysing methylmercury (MeHg), the most toxic organic form of Hg, in environmental samples. It is a purge and trap system based on gas chromatography (GC) separation and cold vapour atomic fluorescence spectrometry (CV AFS) detection, and is extremely sensitive (even < 0.002 ng/L for 40 ml samples). It complies with EPA method 1630, used for the determination of MeHg in water, sediments, biological tissues, etc.

The water-sediment interface is a focal point in the study of the biogeochemical cycles of trace elements and nutrients in the aquatic environment, as it is the site of important processes involving the remineralisation of organic matter. The result of the biogeochemical processes taking place are benthic fluxes representative of the variation over time of the concentrations of solutes present in the water above the sediment and therefore of the mobility of contaminants. This result can be achieved through the use of benthic chambers positioned on the seabed, suitably built and equipped so that samples can be taken in completely undisturbed conditions.

As an alternative to in situ benthic chambers, the study of contaminant mobility at the water-sediment interface can be carried out in the laboratory, under controlled environmental conditions (oxygenic and anoxygenic), using incubated chambers.

One of the peculiarities of mercury is its high volatility, which favours its natural release into the atmosphere from soil surface. Specific flux chambers can be used to monitor this process. The chambers are coupled with the Lumex RA915-M portable gaseous mercury analyser, which uses an internal pump to move air through the chamber. Based on the variation in gaseous mercury concentrations in the headspace of the chamber, recorded in real time by the analyser, it is possible to calculate the flux of the contaminant from the confined surface. Thanks to the speed of measurement, the non-stationary flux chamber (“accumulation chamber”) technique can be applied to map diffuse mercury emissions from soils at contaminated sites, in accordance with the provisions of SNPA Guidelines 15-2018.

The same approach described for monitoring gaseous mercury fluxes at the soil-air interface can also be adapted for in situ measurement of emissions at the water-air interface. In this case, the chambers must be mounted on appropriate floating supports so that the side walls are partially submerged in water. This prevent the intrusion of external air inside the chamber during measurements.

MercuRILab is an integral part of TrEELab (Trace Elements in the Environment Laboratory), where the expertise of environmental geochemists is combined with that of their analytical chemistry colleagues from the Department of Chemical and Pharmaceutical Sciences (DSCF) and clinicians from the Occupational Medicine Clinical Unit of the Department of Medical, Surgical and Health Sciences (DSM). The equipment available at the TrEELab laboratories allows the determination of element concentrations in virtually all environmental matrices.

Inductively Coupled Plasma-Atomic Emission Spectroscopy (ICP-AES) is a versatile and accurate analytical technique used for determining the content of several chemical elements in water samples or in solutions derived from mineralisation of solid matrices. This technique is based on the excitation of the sample by the energy supplied by the high temperatures of the plasma (up to 10000 K). The instrument measures, for each element, the optical radiation emitted by the atoms during the return to their ground state. The detection limits achievable with this technique are in the range of μg/L, with a stable and highly reproducible signal. 

Inductively coupled plasma mass spectrometry (ICP-MS) is one of the most widely used analytical techniques for determining trace chemical elements. ICP-MS is characterised by greater instrumental sensitivity than ICP-AES. ICP-MS allows measurements in the order of ng/L to be obtained. The difference between this instrument and ICP-AES lies in the detector. While ICP-AES measures the radiation emitted by excited atoms in the form of plasma, ICP-MS directly measures the mass of atoms passing through the detector. By integrating the two techniques, chemical analyses can be performed on both major and trace elements.

This instrument allows rapid determination of the concentrations of a wide range of elements (with atomic mass greater than magnesium) in solid samples. Although it does not reach the detection limits of other analytical techniques such as ICP-MS or ICP-OES, the possibility of performing non-destructive analyses on samples as they are means that this instrument can be used in a variety of fields, ranging from the analysis of environmental matrices (soils, sediments, rocks) to the analysis of cultural heritage (archaeological finds) to applications for quality control on metal alloys or precious objects or for the analysis of metal content compliance in consumer or electronic products (RoHS Directive). The instrument can operate both in a benchtop configuration and in portable mode directly in the field.

Ion chromatography is a widely used technique for determining major anions in water. Thanks to a specific column coupled with an electrical conductivity detector, the Dionex ICS-3000 ion chromatograph allows the determination of fluorides, chlorides, bromides, nitrates, phosphates and sulphates up to concentrations in the order of 0.1 mg/L. The different anions are identified based on their specific retention time within the column.

The chemical analysis of inorganic matrices such as soils, sediments and rocks to determine the total concentrations of major and trace elements requires that the powdered samples be completely solubilised by means of a “total” acid attack in a closed microwave system (or digester). This operation uses a mixture of strong acids to obtain a homogeneous solution without altering the original chemical composition of the solid samples being tested. The method used for the mineralisation of soils and sediments complies with EPA 3052, but the microwave system can be used with alternative extraction solutions depending on specific requirements.