CM5018
CM5330
The CM5018 allows for the determination of trace levels of inorganic carbon within solid samples. This analytical technique is advantage over traditional combustion methods in that inorganic carbon is determined directly, rather than through subtraction of inorganic carbon from total carbon, which is subject to inherent calculation error.
The technique is summarised as follows:
- Sample Purging: The solid is weighed into a clean reaction vessel and continuously flushed with a CO₂-free carrier gas. This completely strips out atmospheric carbon dioxide contamination before any chemical reaction takes place.
- Selective H₃PO₄ Acidification: The sample is injected with a solution of ortho-phosphoric acid (H₃PO₄) and heated to facilitate carbonate mineral dissolution. Phosphoric acid is selectively aggressive; it rapidly decomposes inorganic carbonate mineral structures (such as calcite, dolomite, ankerite and even sparingly soluble magnesite), to evolve gas phase carbon dioxide (CO₂). Critically H₃PO₄ is a non-oxidising gas and does not react with organic C, and itself is non-volatile.
- Gas Phase Scavenging: The evolved CO₂ gas is carried by the gas stream through a series of specific post-scrubbers. These filtration loops neutralize and remove potential acid gas interferences (such as H₂S or SO₂ generated from high-sulfide ores) before they reach the detector.
- Absolute Coulometric Titration: The purified stream bubbles into a UIC CM5018 Coulometer cell containing a specialized monoethanolamine solution and a colorimetric pH indicator. As the absorbed CO₂ reacts to form carbamic acid, the solution’s colour fades. The instrument detects this change photometrically and generates a highly accurate electrical current to electrochemically restore the initial indicator state. Faraday’s Law is applied to calculate the precise mass of inorganic carbon down to sub-microgram sensitivity.
Why UIC H₃PO₄ Carbonate Profiling is required
- Trace level inorganic carbon determination: The highly sensitive detection technique allows determination of carbonate carbon down to ppm levels allowing the accurate determination of low ppm Neutralisation Potential determination in mining waste materials.
- Reduced error in detection: Direct determination of inorganic carbon reduces the reliance on subtractive methods and associated calculation error
- Determination of available carbonate: The technique can be used on materials without prior size reduction (i.e. raw tailings) to determine the available inorganic carbon.
- Complimentary technique to ANC and ABCC methods: The coulometric determination can be complimentary to determination of neutralisation potential through other techniques (i.e. ABCC and ANC methods) isolating the inorganic carbon component only.
- Direct Support for Mineral Carbonation R&D: For advanced mine waste carbonation studies and enhanced weathering R&D, tracking small changes in solid-phase inorganic carbon is critical. UIC coulometry provides the high resolution needed to evaluate how effectively mine tailings capture and trap atmospheric CO₂ as solid minerals.