Caron (C), Hydrogen (H), Nitrogen (N), and Oxygen (O) are the building elements of organic compounds. CHNO analyzers are extensively employed to detect their presence and their amounts for determining the analytical chemistry of organic substances. The article delves into the basics and working principles of CHNO analyzers.
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Introduction
Elemental analyzers of different types are employed in industries all over the world to determine the concentration of various elements. Qualitative analysis is performed to determine what elements are present in a sample, while quantitative determines the amount of each element present in a sample.
CHNO analyzers are used for elemental analysis of organic elements. Various industries, such as the environmental industry, chemical sector, materials sciences, and agriculture, among others, use CHNO analyzers to determine the presence of Carbon, hydrogen, nitrogen, sulfur, and oxygen.
CHNO analyzers allow for efficient and quick detection of elements without any extensive sample preparation. The sample size does not affect the detection of substances by the CHNO analyzers. This is the reason CHNO analyzers are utilized extensively in every major industry.
Historical Context
The combustion analysis of a specimen, an integral aspect of CHNS analysis, for altering the flame's color may well be one of the earliest techniques for elemental analysis. Back in 1556, a German metallurgist by the name of Georgius Agricola authored the first documented paper on this subject.
He observed that various ores, when introduced into a flame, caused a modification in "the color of fumes." This observation was employed for qualitative analysis and is regarded as the pioneer of modern-day elemental analyzers, including CHNO analyzers.
Fundamental Principle
CHNO combustion analysis performed within the CHNO analyzer relies on the complete and instantaneous oxidation of a sample through "flash combustion," which transforms all organic and inorganic substances into combustion products. The resulting combustion gases produced within the CHNO analyzer, namely H2O, CO2, and N2, are then employed to provide concentration details for the individual components within the mixture.
This elemental analysis technique performed by using CHNO analyzers is invaluable for determining the elemental composition, purity, and empirical formula of unknown compounds, as it typically reveals the weight percentage of carbon (C), hydrogen (H), nitrogen (N), sulfur (S), and oxygen (O) in a given compound.
This analytical approach finds extensive utility in characterizing chemicals in natural products, materials science, organic and inorganic synthesis, pharmaceuticals, and other fields by employing the suitable type of CHNO analyzers.
After the analysis, CHNO analyzers have different methods for the detection of gases. CHNO analyzers are utilized in conjunction with gas chromatography separation equipment, followed by the thermal conductivity detection method, which is utilized to find the concentration of gases.
To quantify the elements accurately, the calibration method incorporated with the CHNO analyzers is essential for each element. This calibration is achieved through the utilization of high-purity 'micro-analytical standard' compounds.
The next essential step is the detection of gases by the CHNO analyzers. The detection of carbon is usually accomplished by the CHNO analyzers using a non-dispersive infrared (NDIR) method that measures the absorption of infrared radiation by CO2.
Hydrogen and nitrogen, on the other hand, are detected through thermal conductivity detectors incorporated within the CHNO analyzers that sense variations in the thermal conductivity of gases. Oxygen detection is reliant on paramagnetic or electrochemical sensors, which pick up on the magnetic susceptibility or electrochemical reactions associated with oxygen occurring during the analysis process of CHNO analyzers, respectively.
Applications of CHNO Analyzers
CHNO analyzers hold a crucial position in the pharmaceutical sector, where precise elemental analysis stands as a critical element of quality control. Pharmaceutical companies employ CHNO analyzers to ascertain the composition of drug compounds, guaranteeing adherence to regulatory requirements.
The precision offered by CHNO analyzers aids in the refinement of drug formulations and the surveillance of pharmaceutical ingredient purity, contributing to enhanced pharmaceutical quality and compliance.
Environmental scientists heavily depend on CHNO analyzers for the evaluation of soil and plant samples. The analysis of soil's elemental makeup offers valuable information regarding nutrient content, organic matter, and contamination levels.
Additionally, elemental Analysis by Mass Spectrometry (EA-MS) is also applied in environmental studies in conjunction with the CHNO elemental analyzers. This method is also particularly useful in mass percentage detection of nitrogen, oxygen, and sulfur, integrating combustion, gas chromatography, and mass spectrometry to precisely measure each element separately.
Furthermore, CHNO analyzers play a vital role in identifying and quantifying pollutants, thereby advancing our comprehension of environmental pollution and its impact.
Agricultural researchers utilize CHNO analyzers to evaluate the nutritional composition of both crops and livestock feed. To ensure comprehensive nutritional assessment, in addition to CHNO analyzers, X-ray fluorescence spectroscopy is employed for the detection of inorganic elements, ensuring the adequacy of nutrition in agricultural practices.
Methods such as Neutron activation analysis (NAA) may be used for the detection of nitrogen in the agriculture sector; however, it is not an accurate method for carbon and hydrogen detection, so CHNO analyzers are still the number 1 choice in the agricultural field.
Are CHNO Analyzers the Best Choice for All Cases?
CHNO analyzers are the most preferred choice for the detection of carbon, hydrogen, nitrogen, oxygen, and sulfur. However, they are not the most suitable choice in every analysis. It is highly dependent on the state of the sample (i.e. the sample may be in a solid, liquid, or volatile state), specimen form (powdered form or thin films), the specimen size, and the constraint of time and financial resources.
For the sample containing a wide variety of elements along with the organic substances, X-ray photoelectron spectroscopy (XPS) and inductively coupled plasma (ICP) can be employed with the CHNO analyzer detection process to deliver a more comprehensive elemental analysis.
The CHNO analyzers are essential for industrial analysis; that is why famous manufacturing companies all over the world are developing new and improved CHNO analyzers with each passing day. The ability of CHNO analyzers for accurate elemental analysis for the materials science and engineering sector, food sciences, petrochemical, and gas industry makes them the ideal technology available nowadays.
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References and Further Reading
Edwards, G., (2020). A Brief History Of Elemental Analysis. [Online]
Available at: https://www.artemis-analytical.com/a-brief-history-of-elemental-analysis/
Elemental Analysis Inc., (2023). CHNO Combustion Services. [Online]
Available at: https://elementalanalysis.com/chno/
Jordi Labs, (2023). CHNO by Combustion. [Online]
Available at: https://jordilabs.com/lab-testing/technique/elemental-analysis/chno/
Measurlabs, (2023). CHN(O)S Elemental Analysis. [Online]
Available at: https://measurlabs.com/methods/chnos-elemental-analysis/
Raja, P., (2023). Elemental Analysis. [Online]
Available at: https://chem.libretexts.org/Bookshelves/Analytical_Chemistry/Physical_Methods_in_Chemistry_and_Nano_Science_(Barron)/01%3A_Elemental_Analysis
The Royal Society of Chemistry, (2008). CHNS Elemental Analysers. [Online]
Available at: https://www.rsc.org/images/CHNS-elemental-analysers-technical-brief-29_tcm18-214833.pdf
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