National Centre for Earth Science Studies

Geochemical Analytical Laboratory

Geochemical analytical laboratory is the integral part of the Central Chemical Laboratory (CCL) at NCESS with an objective of providing high-quality geochemical analytical services and supports the research on soil, rock and sediment which are the vital resources of the natural environment that are put under severe pressure by multiple socio-economic utilizations along with the water. Geochemical investigations of earth system resources (rock/soil/sediment) provide the adequate information on mechanisms that are responsible for changes in the natural environment. The lab not only offers analytical services to NCESS, but also provides the services to other government agencies, public industries, other institutional researchers and private clients on the payment basis. This laboratory equipped with state-of the art instruments/facilities and offers the analysis for C, H, N and S elements, total organic carbon (TOC), total carbon (TC), particle size analysis along with textural characterization and loss of ignition for soil/sediment samples. The lab also offers soil/sediment digestion methods using with high concentrated acids and fume hood for heavy metals, rare earth elements and trace metal analysis. List of instruments/facilities available with geochemical analytical laboratory and their brief details are provided below.

Instruments/Facilities available with Hydrochemical Analytical Laboratory:

1. Total Organic Carbon analyser (TOC)
2. C, H, N and S elemental analysis (CHNS analyser)
3. SediGraph particle size analyser
4. Textural characterization and sample digestion facility for soil/sediment

Total Organic Carbon Analyser
Make: Elementar; Model: Vario TOC Select

The Total Organic Carbon (TOC) is one of the most important composite parameters in the assessment of the organic matter present in the given sample of water or soil or sediment. Total organic carbon (TOC) is the amount of carbon found in an organic compound and is often used as a non-specific indicator of water quality. In addition to the TOC, parameters like Total Carbon (TC), Total Inorganic Carbon (TIC) are also measured where the TC is the sum of the TOC and TIC. Analytical technologies utilized to measure TOC are of completely oxidizing the organic molecules in an aliquot of sample water/sediment to carbon dioxide (CO2), there by measuring the resultant CO2 concentration and expressing this response as carbon concentration. The TOC analyser first digests the inorganic carbon with the help of Ortho phosphoric acid which may be present in the water from sources such as dissolved CO2 and bicarbonate, and then the CO2 generated from the oxidation of organic molecules in the sample is measured.

C, H, N and S elemental analyser (Vario EL Cube)
Make: Elementar; Model: Vario EL Cube

The C, H, N and S elemental analyser finds utility in determining the percentages of Carbon, Hydrogen, Nitrogen, and Sulphur of the given water or soil or sediment sample. And the working principle is based on the "Dumas method" which involves the complete and instantaneous oxidation of the sample by "flash combustion". The combustion products are separated by a chromatographic column and detected by the thermal conductivity detector (T.C.D.) which gives an output signal proportional to the concentration of the individual components of the mixture. Here the present CHNS analyser at CCL uses the built-in chromatographic column which converts the sample compound and elutes it in the form of NO2, CO2, SO2, H2O which are then detected with the help of thermal conductivity detector (T.C.D.).

SediGraph
Make: Micromeritics; Model: SediGraph III plus

Micromeritics SediGraph has remained the standard instrument for particle size analysis. Particle size distribution is measured using the sedimentation method. Particle mass is measured directly via X-ray absorption. The SediGraph determines the equivalent spherical diameter of particles ranging from 300 to 0.1 micrometers. The SediGraph III Plus is equipped with a versatile, easy-to-use user interface that includes point-and-click menus, customizable reports, tables and data export features. In addition to tabular data, different graphical analysis plot types are also available including: cumulative mass, area, and number, settling velocity distribution, process control charts, log probability, baseline/full scale references, frequency distribution, regression analyses and difference from reference.