Field acquisition of geochemical data (soil gas, free gas and water sampling). Photographs of the campaign activities within the research activities of the Fluid Geochemistry Laboratory.
Field acquisition of geochemical data (soil gas, free gas and water sampling). Pictures of the filed surveys performed by the Fluid Geochemistry Laboratory in the frame of research activities.
Examples of geochemical data processing of both water and gas. Processing examples of geochemical data of groundwater and gas.
Figure 1 - Example of gas chromatographic curve.
Figure 1 – Example of gas chromatographic curves
Figure 2 - CP4900 gas chromatograph used to carry out laboratory analyzes of gas samples in soils, free gas and gas dissolved in water.
Figure 2 – CP 4900 Gaschromatograph used to carry out laboratory analyzes of soil gas samples, free gas and dissolved gas in the groundwater.
Figure 3 - Example of calibration curve.
Figure 3 – Example of calibration curves
Figure 4 - Thermal desorption DANI Master TD gas chromatograph.
Figure 4 - DANI Master TD gaschromatograph with thermal desorption.
Figure 5 – Simplified diagram of the separation of substances inside the chromatographic column
Figure 5 – Simplified diagram of the separation of substances within the chromatographic column 
Figure 6 – Example of chromatogram
Figure 6 – Example of chromatogram 
Figure 7 – Block diagram of a modern ion chromatography system
Figure 7 – Block diagram of a modern ion chromatography system
Figure 8 – Thermo Scientific ICS-900 ion chromatograph and autosampler
Figure 8 –Thermo Scientific ICS-900 ion chromatograph and autosampler
Figure 9 – Portlab S001.2 ion chromatograph and autosampler
Figure 9 – Portlab S001.2 ion chromatograph and autosampler
Figure 10 – Example of chromatogram and calibration curve
Figure 10 – Example of chromatogram and calibration curve
Figure 11 – Benchtop titrator
Figure 11 – Benchtop titrator
Figure 12 – Ultrapure water production unit
Figure 12 – Ultrapure water production unit
GEOCHEMISTRY LABORATORY OF FLUIDS
Supervisor: Dr. Alessandra Sciarra
FLUID GEOCHEMISTRY LABORATORY
Head: Alessandra Sciarra
The Fluid Geochemistry laboratory of the Rome1 Section is equipped with various instruments for the chromatographic analyzes of water and gas and for the determination of the chemical-physical parameters of the water, of the geogas concentrations and for the measurement of the exhalation flows in the countryside.
The Fluid Geochemistry laboratory supports research in a wide range of topics related to environmental impact such as groundwater contamination and assessment of geogas emissions into the atmosphere, analysis of natural gas deposits, characterization of fluids from petroleum and geothermal reservoirs, mineral exploration, natural hazards, as well as monitoring in volcanic and seismically active areas.
The Roma1 Section Fluids Geochemistry Laboratory is equipped with various instruments for water and gas chromatographic analysis, for determination of the chemical-physical parameters of the waters, the geogas concentrations and flux measurement in the field.
The Fluids Geochemistry Laboratory supports research in a wide range of topics related to environmental impact such as groundwater contamination and the evaluation of geogas emissions into the atmosphere, analysis of natural gas deposits, characterization of fluids from oil and geothermal reservoirs, to mineral exploration, to natural hazards, as well as to monitoring in volcanic and seismicly active areas.
Purpose
Maintenance, management and development of the instrumental park for the geochemical characterization of sites of environmental (terrestrial and marine), volcanic and seismic interest.
Provide support to research and monitoring activities carried out within both national and international research and development projects.
Aims
Maintenance, management and development of the fleet instrumental for geochemical characterization of study sites on environmental, volcanic and seismic settings.
Provide support for research and monitoring activities carried out in national and international research projects and development.
All instrument and analysis requests are managed thanks to an electronic calendar available online.
All the requests for instruments and analysis are managed by an electronic calendar available online.
GAS CHROMATOGRAPHY (Head Alessandra Sciarra)
GASCHROMATOGRAPHY (Head Alessandra Sciarra)
Gas chromatography is a widely used analytical method for the separation, identification and quantitative determination of the various components present in a mixture in the gaseous state. This method uses a gas as the mobile phase called carrier gas, usually argon or helium, and exploits the different affinities of the molecules towards two different phases: the stationary phase and the mobile phase. The gas sample is subjected to a flow by the carrier gas (mobile phase) and is directed inside the chromatographic column where there are substances (stationary phase) capable of separating the various components of the gaseous mixture. At the end of the column there are one or more detectors which translate the presence of a substance into an electrical signal. The electrical signal, which can be proportional to the concentration of the detected component or to its mass, is generally transformed into a graph (gas chromatogram, Figure 1).
Gaschromatography is an analytical method widely used for the separation, identification and quantitative determination of the various components present in a mixture in the gaseous state. This method uses a gas as a mobile phase called carrier gas, usually argon or helium, and exploits the different affinities of the molecules towards two different phases: the stationary and the mobile phase. The gas sample is subject to a flow by the carrier gas (mobile phase) and is directed inside the chromatographic column where substances (stationary phase) are present capable of separating the various components of the gas mixture. At the outlet of the column there are one or more detectors that transform the presence of a substance into an electrical signal. The electrical signal, which can be proportional to the concentration of the detected component, is generally transformed into a graph (gas chromatogram, Figure 1).
The gas chromatography laboratory of the Rome1 Section is able to carry out quantitative chemical analyzes of the gaseous species sampled during the gas campaigns in the soil, of the bubbling dry phase from springs or aquifers, of the gases dissolved in the water.
The laboratory is equipped with the following instruments:
1) The Agilent 4900 microGC (Figure 2), a very delicate and high-precision instrument, features a thermal conductivity detector (TCD). This detector matches thermal conductivity differences between the carrier gas and the sample components to be analyzed. In a TCD, the signal generated by the passage of the carrier gas is compared with that of a comparison (equivalent) gas. The passage of the components of the sample inside the detector causes an imbalance of the signal proportional to its concentration.
Inside it has two different types of columns:
1. Molsieve 5Å column having a length of 20 m, and is dedicated to the separation of the following gaseous components: Helium (He), Neon (Ne), Hydrogen (H2), Carbon Monoxide (CO), Nitrogen (N2), Oxygen ( O2) and methane (CH4).
2. PoraPlot Q (PPU) column having a length of 10 m, dedicated to the separation of the following gases: Air, Methane (CH4), Carbon Dioxide (CO2), Acetylene (C2H2), Ethane (C2H6), Ethylene (C2H4) and Acid Sulfuric (H2S).
The concentration of the samples is established on the basis of the calibration curve (Figure 3) and of the previously constructed method, by means of specially analyzed standard gases, with concentrations of the various species varying between a few ppm and 100% by volume.
Gaschromatography Laboratory of the Roma1 Section is able to carry out quantitative chemical analysis of the gaseous species sampled during the soil gas surveys, of the bubbling phase from pools or aquifers, of the dissolved gases in the waters.
Laboratory is equipped with the following instruments:
1) The Agilent 4900 microGC (Figure 2), a very delicate and highly accurate instrument, is equipped with a thermal conductivity detector (TCD). This detector corresponds to differences in thermal conductivity between the carrier gas and the components of the sample to be analyzed. In a TCD the signal generated by the transit of the carrier gas is compared with an equivalent gas. The transit of the sample components inside the detector causes an imbalance of the signal proportional to its concentration.
Inside it has two different types of columns:
1. Molsieve 5Å column having a length of 20 m is dedicated to the separation of the following gaseous components: Helium (He), Neon (Ne), Hydrogen (H2), Carbon Oxide (CO), Nitrogen (N2), Oxygen ( O2) and methane (CH4).
2. PoraPlot Q (PPU) column with a length of 10 m is dedicated to the separation of the following gases: Air, Methane (CH4), Carbon Dioxide (CO2), Acetylene (C2H2), Ethane (C2H6), Ethylene (C2H4 ) and Sulfuric Acid (H2S).
The concentration of the samples is established on the basis of the calibration curve (Figure 3) and the previously constructed method, by means of standard gases with concentrations varying between a few ppm and 100% by volume.
2) The DANI Master TD thermal desorption gas chromatograph, coupled to a gas chromatograph equipped with a DANI Master GC electron capture detector (GC-ECD).
This instrument allows to analyze the perfluorocarbons present in traces in the gases.
Such an analysis can only be performed after sampling from the probe through silicone tubing, and stainless steel tubing (6,35 mm OD × 89 mm) packed with graphitized black CarbotrapTM 100.
2) The DANI Master TD thermal desorption gas chromatograph, coupled with a gas chromatograph equipped with a DANI Master GC electron capture detector (GC-ECD).
This instrument allows to analyze the perfluorocarbons present in traces in the gases.
This analysis can be carried out only after sampling from the probe through a silicone tube, and stainless steel tubes (6.35 mm OD × 89 mm) packed with CarbotrapTM 100 graphitized black.
ION CHROMATOGRAPHY (Head. Daniele Cinti)
ION CROMATOGRAPHY (Head. Daniele Cinti)
Ion chromatography (IC) is an analytical technique that allows the separation and recognition of the chemical constituents of an aqueous solution present in ionic form. The separation takes place through the interaction between a liquid (the mobile phase) and a solid (the stationary phase), which leads to a differential distribution of the components of the solution based on the chemical nature of the substances and their degree of affinity with the two phases (Figure 5). The mobile phase (the eluent) contains and transports the sample to be analyzed and consists of a solution of carbonate and sodium bicarbonate (Na2CO3/NaHCO3) for the analysis of anions and a solution of methanesulphonic acid (CH3SO3H) for that of cations. The stationary phase, contained within the chromatographic column, consists of granules of insoluble porous material carrying reactive groups (amino, carboxylic, sulphonic) on which ions capable of exchanging with the ions of the mobile phase are labilely bound. It is through this process of ion exchange between the ions contained in the stationary phase and those contained in the aqueous solution that the separation of the ions takes place.
Ion-chromatography (IC) is an analytical technique able to separate and recognize the chemical constituents of an aqueous solution present in ionic form. The separation occurs through the interaction between a liquid (the mobile phase) and a solid (the stationary phase), which leads to a differentiated distribution of the components of the solution based on the chemical nature of the substances and their affinity with the two phases (Figures 5). The mobile phase (the eluent) contains and transports the sample to be analyzed and consists of a solution of sodium carbonate and bicarbonate (Na2CO3 / NaHCO3) for the analysis of anions and a solution of methanesulfonic acid (CH3SO3H) for the analysis of cations. The stationary phase, contained within the chromatographic column, consists of granules of insoluble porous material that carry reactive groups (amino, carboxylic, sulphonic) on which ions able of exchanging with the ions of the mobile phase are loosely bound. It is through this process of ion-exchange between the ions contained in the stationary phase and those contained in the aqueous solution that the separation of the ions takes place.
The presence of a detection system (conductometric, infrared, etc.) of the substances leaving the chromatographic column allows to obtain the chromatogram (Figure 6), which is the graphical representation of the separation process through which the components of the solution and its relative concentrations are determined. On the chromatogram each analyte is represented by a peak whose exit time is a function of the speed at which it travels inside the chromatographic column, which depends on the affinity of the substance with the mobile and stationary phases, and whose area is a function of the concentration in solution.
The presence of a detection system (conductometric, infrared, etc.) of the substances leaving the chromatographic column allows to obtain the chromatogram (Figure 6), ie the graphical representation of the separation process through which the components of the solutions are identified and their relative concentrations are determined. On the chromatogram each ion is represented by a peak characterized by an exit time as a function of the speed at which it travels inside the chromatographic column, which depends on the affinity of the substance with the mobile and stationary phases, and an area as a function of its concentration in solution.
The block diagram of a modern ion chromatography system is shown in figure 7. The sample is introduced into the eluent stream via an injection valve, which does not interrupt the flow continuity, and transported through the chromatography column where the separation of the analytes. The analytes present in the sample travel in the column at different speeds and at different times reach a flow detector located downstream of the separation column.
The block diagram of a modern ion chromatography system is shown in figure 7. The sample is introduced into the eluent stream by means of an injection valve, which does not interrupt the continuity of the flow, and is transported through the chromatographic column where the separation of the ions takes place. The ions in the sample solution travel through the column at different speeds and reach at different times a flow detector located downstream of the separation column.
The fluid geochemistry laboratory of the Rome Section1 is equipped with 2 chromatographs: a Thermo Scientific Dionex ICS-900 (Figure 8) and a Portlab S001.2 (Figure 9). Both allow separation with isocratic elution, ie using an eluent whose composition does not vary during the analysis, while the detection takes place in a conductometric cell. In ion chromatography the main anions (F-, Cl-, Br-, NO2-, NO3-, PO43-, SO42-, I-) and cations (Li+,Na+, NH4+, K+, Mg2+, Ca2+) contained in water solution. Applications of ion chromatography are mainly chemical analyzes of natural waters (groundwater, thermal, meteoric, marine) for research purposes and geochemical and environmental monitoring.
The Laboratory of Fluid Geochemistry of the Rome1 Section is equipped with 2 chromatographs: a Thermo Scientific Dionex ICS-900 (Figure 8) and a Portlab S001.2 (Figure 9). Both allow separation with isocratic elution, ie using an eluent whose composition does not vary during the analysis, while the detection takes place in a conductometric cell. In ion chromatography the main anions (F-, Cl-, Br-, NO2-, NO3-, PO43-, SO42-, I-) and cations (Li+,Na+, NH4+, K+, Mg2+, Ca2+) contained in water solution are analysed. Applications of ion chromatography are mainly chemical analysis of natural waters (groundwater, thermal, meteoric, marine) for geochemical and environmental research and monitoring purposes.
Calibration curves (Figure 10) are constructed daily by analyzing standard solutions at different and known concentrations of each ion species. These are used to determine the ionic concentrations of aqueous solutions of unknown concentration.
Calibration curves (Figures 10) are constructed daily by analyzing 6 standard solutions at different and known concentrations of each ionic species. These are used to determine the ionic concentrations of aqueous solutions of unknown concentration.
OTHER EQUIPMENT
OTHER INSTRUMENTS
Other instrumentation used for sampling and analyzing aqueous solutions includes pH meters, conductivity meters and a Metrohm Titrino 785 benchtop titrator (Figure 11). The laboratory is also equipped with a technical balance (3 decimal places), fume hood and Millipore MILLIQ Direct Q-3 System ultrapure water production unit (Figure 12).
Other instrumentation used for sampling and analysis of aqueous solutions includes pH meters, conductivity meters and a benchtop titrator Metrohm Titrino 785 (Figures 11). The laboratory is also equipped with a technical weight scale (3 decimal digits), extractor hood and Millipore MILLIQ Direct Q-3 System ultrapure water production unit (Figures 12).