CHNSanalyse

CHNSanalyse, or CHNS analysis, is an elemental analysis technique used to determine the carbon, hydrogen, nitrogen, and sulfur contents of a sample. It is commonly performed with a CHNS analyzer in organic chemistry, materials science, and related fields. The sample is weighed and introduced into a combustion reactor where it is oxidized in excess oxygen at high temperature. Carbon is converted to carbon dioxide, hydrogen to water, nitrogen to nitrogen (N2) or NOx, and sulfur to sulfur dioxide (SO2). The resulting gases are carried by an inert carrier gas to detectors that quantify each element.

Detectors used for CHNS analysis typically include infrared or thermal conductivity detectors for CO2 and H2O, chemiluminescence or other methods for nitrogen, and infrared detection for SO2 from sulfur. The instrument converts the detector responses into mass percentages, usually reported as weight percent C, H, N, and S. The method is destructive, fast, and suitable for routine analysis, often requiring only milligram to tens of milligrams of sample.

Preparation and calibration are critical. Samples should be dry and homogeneous; pre-treatment may be necessary for materials containing halogens or moisture. Calibration uses certified reference materials with known C, H, N, and S contents to ensure accuracy and precision. Blank corrections and instrument maintenance are part of quality control.

Applications of CHNS analysis span fuels, polymers, foods and feeds, soils, pharmaceuticals, and environmental samples. It provides essential information on elemental composition, supporting material characterization, quality control, and compliance with specification standards. Some systems also offer CHN(O) capabilities or separate sulfur determination enhancements for broader elemental profiling.