Geochemistry

TC/TOC/S Analysis (Solid Sample_bulk)

The CS744 LECO in­stru­ment meas­ures total car­bon, or­ganic car­bon and sul­phur con­tents. The ana­lysis is per­formed by heat­ing 0.1 g of ho­mo­gen­ised ma­ter­ial in a ceramic dish and meas­ur­ing the res­ult­ing CO₂ and SO₂ in IR cells, which provide car­bon and sul­phur con­tents.
Car­bon­ate con­tent (C_carb) is de­term­ined fol­low­ing two steps. First, total car­bon con­tent is ana­lysed in one sample. Then, car­bon con­tent is meas­ured in a sample that was pre­treated with hy­dro­chloric acid to re­move car­bon­ates. C_carb-con­tent is then cal­cu­lated from these two meas­ure­ments.
The in­stru­ment works ac­cord­ing to stand­ard test meth­ods, such as ISO 9556, ISO 10719, ASTM E1941, ASTM E1019, ASTM E1941 and the in­ter­na­tional equi­val­ences.

The measurements are conducted on aliquots (100 mg) of a ground and homogenized solid sample.

Species:
TC - Total carbon, TOC - total organic carbon, TS - total sulfur.
Carbonate content is calculated from these result.

Assembly:
LECO CS 744 carbon-sulfur analyzer with Shuttleloader

Measuring principle:
Approximately 100 mg of the homogenized sample is weighed in exactly in a sterile ceramic boat and combusted at 2200°C in a stream of purified Oxygen (Carrier gas). The evolved CO₂ and SO₂ are measured with a non-dispersive infrared detector to quantify TC and TS sample content. To determine TOC, another 100 mg sample aliquot is first decalcified using 12.5% HCl to remove inorganic carbonate, dried and then combusted / analyzed as described above. Total inorganic carbon (TIC) is determined by subtracting TOC from TC. Data is reported in weight percent (wt%) dry sample.

Reference material:
Commercial certified reference material and certified one-use reference pieces.

Measurement precision:
TC/TOC - C: 1-σ ± 1,0% C
Sulfur - S: 1-σ ± 1,5% C


 

ED-XRF Analysis (Solid Sample_bulk)

The measurements are conducted on aliquots (4000 mg) of ground and homogenized solid samples.

Species:
Bulk elemental composition

Assembly:
XRF PANalytical Epsilon 3^XLE 

Measuring principle:
Exactly 4000 mg of the homogenized sample is weighed in a sample vial and compacted with 25 kg of pressure. Ten prepared samples per analytical run are analysed for bulk elemental composition using the benchtop energy dispersive X-ray fluorescence (EDXRF) spectrometer Epsilon 3^XLE (PANalytical).

Reference material:
General - Mastercalibration from over 40 commercial certified reference calibration materials.

Special - Dependent on the exact core material (e.g. mar­ine and fresh­wa­ter sed­i­ments, rocks, soils) additional certified reference material are applied as needed.

Measurement precision:
Based on element, utilized calibration standard and dependent on core material: 1-σ ± 0.1 - 3.0%

C and N Analysis with CHNS Analyzer (Solid Sample_bulk)

C and N are analyzed with a Vario EL3 CHNS analyzer by Elementar.

The measurements are conducted on aliquots (20-30 mg/1g) of a ground and homogenized solid sample.

Species:
TC - Total carbon, TOC - total organic carbon, N - total nitrogen.

Assembly:
Vario EL3 CHNS analyzer by Elementar®

Measuring principle:
To determine TC/N,  ~ 20-30 mg of the homogenized sample is weighed in precisely in a Zinn capsule and combusted at 950°C in a stream of purified Oxygen (Carrier gas). The evolved CO₂ and NO₂ are measured via TCD/IR detection.

To determine TOC, ideally  ~1 g (min. 500 mg) of the homogenized sample is weighed in precisely into a separate glass vial as a second sample aliquot, decalcified using 10% HCl to remove inorganic carbonate, washed and centrifuged. Then a ~ 20-30 mg split of that treated sample aliquot is weighed in precisely in a Zinn capsule and then combusted and analyzed as described above.

Data is reported in weight percent (wt%) dry sample.

Reference material:
Commercial certified reference material.

Determination limit:
TC/TOC - C: 1-σ ± 1,0% C
Nitrogen - N: 1-σ ± 0,1% C