Onwudili Jude Azubuike, Peters Morenike Ajike, Alves Carine Tondo
Energy and Bioproducts Research Institute, College of Engineering and Physical Sciences, Aston University, Aston Triangle, Birmingham B4 7ET, UK.
Energy Engineering Department, Centro de Ciência e Tecnologia em Energia e Sustentabilidade, Universidade Federal do Reconcavo da Bahia, Av. Centenario 697, Feira de Santana 44085-132, Brazil.
Molecules. 2024 Sep 13;29(18):4346. doi: 10.3390/molecules29184346.
Elemental analysis is a fundamental method for determining the carbon, hydrogen, nitrogen, sulphur, and oxygen (CHNSO) contents in organic materials. Automated conventional elemental analysers are commonly used for CHNSO determinations, but they face challenges when analysing volatile organic liquids due to sample losses. This present study explores the combination of gas chromatography-mass spectrometry (GC/MS) and gas chromatography-flame ionisation detection (GC/FID) as a more accurate alternative method for elemental analysis of such liquids. Six different liquid samples containing various organic compounds have been analysed using both a conventional elemental analyser (Method 1) and the combined GC/MS-GC/FID method (Method 2). The results showed that Method 1 gave results with significant errors for carbon (by more than ±10 wt%) and oxygen (by up to ±30 wt%) contents due to volatile losses leading to inaccurate "oxygen-by-difference" determinations. In contrast, Method 2 gave more accurate and consistently representative elemental data in a set of simulated samples when compared to theoretical elemental data. This work proposes the use of the GC/FID method as a reliable alternative for CHNSO analysis of volatile organic liquids and suggests that employing the GC/FID technique can mitigate the common errors associated with conventional CHNSO analysis of such samples. However, successfully using Method 2 would depend on the skills and experience of users in qualitative and quantitative organic chemical analyses by gas chromatography.
元素分析是测定有机材料中碳、氢、氮、硫和氧（CHNSO）含量的基本方法。自动化传统元素分析仪通常用于CHNSO测定，但在分析挥发性有机液体时，由于样品损失，它们面临挑战。本研究探索了气相色谱 - 质谱联用（GC/MS）和气相色谱 - 火焰离子化检测（GC/FID）相结合的方法，作为对此类液体进行元素分析的一种更准确的替代方法。使用传统元素分析仪（方法1）和GC/MS - GC/FID联用方法（方法2）对六种含有各种有机化合物的不同液体样品进行了分析。结果表明，由于挥发性损失导致“差减法测氧”不准确，方法1得出的碳含量（误差超过±10 wt%）和氧含量（误差高达±30 wt%）结果存在显著误差。相比之下，与理论元素数据相比，方法2在一组模拟样品中给出了更准确且始终具有代表性的元素数据。这项工作提出将GC/FID方法用作挥发性有机液体CHNSO分析的可靠替代方法，并表明采用GC/FID技术可以减轻与此类样品传统CHNSO分析相关的常见误差。然而，成功使用方法2将取决于用户在气相色谱定性和定量有机化学分析方面的技能和经验。
