CHNSO is an acronym that represents the five most common elements found in organic compounds: Carbon (C), Hydrogen (H), Nitrogen (N), Sulfur (S), and Oxygen (O). Analysing the elemental composition of organic compounds, often referred to as elemental analysis or CHNSO analysis, is a crucial analytical method in organic compound analysis and for quantifying what element is present.
A CHNSO analyzer, also known as an elemental analyzer, gives a quantitative measure of elemental composition, that is, organic elements of a given sample, and also allows the deciphering of the empirical molecular formula of organic substances. The CHNSO Analyzer has multiple uses in many industries and sectors, for example the food and pharmaceutical industry.
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Components of a CHNSO Analyzer
A CHNSO analyzer is a sophisticated instrument designed for the precise determination of the elemental composition of organic compounds. It consists of several key components, each playing a crucial role in a CHNSO analyzer:
- CHNSO Analyzer Sample Chamber and Sample Preparation:
The sample chamber of a CHNSO analyzer is where the organic sample to be analysed is introduced into the instrument. Samples need to be prepared carefully to ensure accurate results.
- CHNSO Analyzer Combustion Unit:
The CHNSO analyzer combustion unit is a central component of the CHNSO analyzer, responsible for breaking down the organic sample into its constituent elements through combustion analysis. It operates by heating the sample in the presence of oxygen (O2), leading to the conversion of carbon (C) and hydrogen (H) into carbon dioxide (CO2) and water (H2O), respectively.
Nitrogen (N) is converted to nitrogen oxides (NOx and then into nitrogen gas (N2), and sulphur (S) is transformed into sulphur dioxide (SO2). The CHNSO analyzer combustion unit's significance lies in its ability to convert the organic material into forms that can be quantified accurately, allowing for the determination of C, H, N, S, and O content.
- CHNSO Analyzer Detectors for Each Element:
After combustion and reduction within the CHNSO analyzer combustion unit, the gases produced are passed through detectors. Each detector is specialized for specific elements, thus allowing the production of data that is quantitative, determining what elements are present.
Process Breakdown of CHNSO Analyzers
CHNSO Analyzer Sample Introduction and Preparation
The analysis by the CHNSO analyzer begins with the introduction of the organic sample into the sample chamber of the CHNSO analyzer. Typically, the CHNSO analyzer sample is dried and finely ground to a consistent powder to ensure uniform combustion and facilitate the release of the elements during analysis. Proper CHNSO analyzer sample preparation is essential as any impurities or incomplete combustion may introduce errors in the analysis.
CHNSO Analyzer Combustion Process
The CHNSO analyzer-prepared sample is introduced into a combustion tube or chamber, where it is exposed to an extremely high temperature (>1000o C), in the presence of pure oxygen (no < 99.9995%) or oxygen-enriched gas, thus initiating the combustion process. The heat breaks down the organic material into its constituent elements.
- Carbon (C) is oxidised to form carbon dioxide (CO2).
- Hydrogen (H) is oxidised to form water vapour (H2O).
- Nitrogen (N) is oxidised to form nitrogen oxides (NOx).
- Sulphur (S) is oxidised to form sulphur dioxide (SO2).
The CHNSO analyzer combustion products are then swept out of the combustion chamber by inert carrier gas such as helium and passed over heated (about 600oC) high-purity copper - which can be situated at the base of the combustion chamber or in a separate furnace. The function of this copper is to remove any oxygen not consumed in the initial combustion and to convert any oxides of nitrogen to nitrogen gas. The gases are then passed through the absorbent traps in order to leave only carbon dioxide, water, nitrogen and sulphur dioxide.
CHNSO Analyzer Detection of Individual Elements
Carbon and Sulphur Detection:
The carbon dioxide (CO2) and sulphur dioxide (SO2) generated from the combustion process are directed to a specialised detector, often a non-dispersive infrared (NDIR) detector. The NDIR detector quantifies the amount of CO2 and SO2, which corresponds to the carbon and sulphur content in the sample.
Hydrogen and Nitrogen Detection:
The water vapour (H2O) and nitrogen gas (N2) produced following the combustion chamber are sent to a thermal conductivity detector (TCD). The TCD measures changes in thermal conductivity caused by the presence of hydrogen or nitrogen, allowing for precise quantification.
Oxygen Detection (Optional):
Some CHNSO analyzers may include an oxygen detector to measure the remaining oxygen content in the combustion gases. This could be built into the NDIR as a paramagnetic analyzer or external zirconia analyzer, whereby the O2 measurement can be used to verify the completeness of the combustion process.
Conclusion
In conclusion, the CHNSO analyzer analysis process involves a meticulous series of steps, including sample preparation, combustion, and specific detection methods for individual elements. It enables accurate quantification of the elemental composition of organic compounds, making it an essential technique in chemistry, materials science, environmental science, and various industries.
Modern CHNSO analyzer technology represents the pinnacle of analytical chemistry precision and efficiency in elemental analysis. Such cutting-edge instruments are engineered to deliver unmatched accuracy and speed in determining the elemental composition of organic compounds. Through advanced technology, precise detectors, and optimised combustion processes, modern CHNSO analyzers excel in providing highly reliable results with exceptional efficiency.
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References and Further Reading
CHNS Elemental Analysers Oxidation Reduction Auto-sampler He O 2 Flash Dynamic Combustion T = 1800 °C Dedicated integrator PC Detector GC Column N 2 CO 2 H 2 O SO 2 [Internet]. 2008. Available from: https://www.rsc.org/images/CHNS-elemental-analysers-technical-brief-29_tcm18-214833.pdf
CHNSO Elemental Analyzers [Internet]. www.just.edu.jo. [cited 2023 Oct 8]. Available from: https://www.just.edu.jo/FacultiesandDepartments/FacultyofScienceandArts/Pages/CHNSO-Elemental-Analyzers.aspx
CHNS-O Determination in Metal Organic Frameworks by Flash Combustion Reference: Velp Internal Procedure Tested with VELP Scientifica EMA 502 CHNS-O Elemental Analyzer (Code F30800100) [Internet]. [cited 2023 Oct 8]. Available from: https://www.velp.com/public/file/VELPApplicationNoteCHNSODeterminationinMetalOrganicFrameworksbyFlashCombustion-284730.pdf
CHN elemental analysis） | Techniques | Fields | Toray Research Center | TORAY [Internet]. www.toray-research.co.jp. [cited 2023 Oct 8]. Available from: https://www.toray-research.co.jp/en/technicaldata/techniques/EA.html
Analyser C. CHNS+O COMBO ANALYSER Analytical Technologies Limited An ISO 9001 Certified Company www.analyticalgroup.net EPC / PRODUCTS / APPLICATION / SOFTWARE / ACCESSORIES / CONSUMABLES / SERVICES [Internet]. [cited 2023 Oct 8]. Available from: http://analyticalgroup.net/Admin/catalogue/CHNSO%20COMBO%20Analyser.pdf
CHNSO Analyser [Internet]. saif.iitm.ac.in. [cited 2023 Oct 8]. Available from: https://saif.iitm.ac.in/popupwindow/chnso.html
Non-Dispersive Infrared Gas Analyzers (NDIR) | Yokogawa Electric Corporation [Internet]. www.yokogawa.com. [cited 2023 Oct 8]. Available from: https://www.yokogawa.com/solutions/products-and-services/measurement/analyzers/gas-analyzers/ftnir-ir/#Overview
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