Mol CS1500

The sample is burned in a furnace under excess oxygen. Carbon oxidizes to CO₂ and sulfur to SO₂. The combustion gases are dedusted and dried, then quantified in non-dispersive infrared measuring cells. Because each gas absorbs infrared light according to its own spectral pattern and absorption is proportional to concentration, the mass fraction follows directly from the signal and the sample weight.

Both instruments work on the same principle: combustion in a horizontal resistance furnace followed by NDIR detection. The difference lies in the layout. The CS1500 has the high-temperature furnace integrated, is built in under 180 litres of volume and is therefore the compact all-in-one instrument for laboratories with limited bench space. The CS1000 works with external Mol Premier® furnaces: Mol Multi Furnace technology connects up to three furnaces to one analyzer. This pays off if you run several matrices at different furnace temperatures or want to add a pre-heating furnace for trace analysis later. Both can be configured with up to four independent infrared detectors.

Carbon from 0.025 mg to 500 mg absolute, sulfur from 0.025 mg to 100 mg absolute. Based on a 500 mg sample weight this corresponds to up to 100 percent carbon and up to 20 percent sulfur. Configuring several measuring cells across different ranges covers this span without diluting samples.

Typically 60 to 120 seconds, depending on matrix and heating program. Signal evaluation and result output are automatic.

The difference lies in how the heat is produced. An induction furnace generates a high-frequency magnetic field that induces currents, and with them heat, in the conductive material itself; temperatures above 2000 °C are possible. That is the right approach for steel and other metals, where the carbon is bound in the matrix and an accelerator such as tungsten or iron is often added. A resistance furnace heats via heating elements, much like an oven, and works up to 1550 °C. In return the temperature is uniform and controllable throughout the run, no high-frequency generator is needed, and as a rule no additives are required, or far fewer. For non-metallic samples such as coal, coke, graphite, soil, cement or waste the attainable temperatures are sufficient – coal, for instance, releases carbon and sulfur completely at around 1300 °C under suitable conditions. There the resistance furnace is the more economical choice: simpler in design, cheaper to run and with no recurring cost for accelerators.

Solid, predominantly organic materials and in part also liquids: coal, coke, oil, ash, catalysts, limestone, gypsum, soils, rubber, waste, graphite, cement, sand, soot, tobacco and plant matter.

The standard sample weight is 300 to 350 milligrams; weights of 500 milligrams and more are possible. The CS1500 processes soil samples up to 10 grams. Higher sample weights reduce the error caused by heterogeneous sample composition and give more representative results.

Crucibles and boats carry carbon of their own. This blank value sits in the same order of magnitude as the contents to be measured in trace analysis and falsifies the result accordingly. The Mol Premier® 1350 Pre-Heating Furnace burns out the sample carriers before use: the carbon blank drops and, above all, becomes reproducible – an important prerequisite for dependable values in the low ppm range.