Average carbon chain length is a key parameter that defines the quality of liquid biofuels. In this paper, a method for the determination of carbon chain lengths of fatty acid mixtures is presented. The approach is based on proton relaxation rates measured by time domain nuclear magnetic resonance. The spin–spin relaxation rates R2 were used for the estimation of the carbon chain lengths. The method was examined for the set of samples with different mean lengths of the main linear carbon chain. Samples were prepared using four different fatty acids and mixtures of two, three or four of these fatty acids. The correlation coefficient between the known and measured values was equal to 0.994. Based on the relaxation theory, a linear-like dependence between the relaxation rate and carbon chain length was briefly shown, which endorses the experimental results. The developed methodology for determining carbon chain lengths offers robustness and rapidity, which are significant advantages when it comes to online use of the method in real industrial environments.

中文翻译：

---

通过时域 NMR 测定脂肪酸混合物的碳链长度


平均碳链长度是决定液体生物燃料质量的关键参数。本文提出了一种测定脂肪酸混合物碳链长度的方法。该方法基于通过时域核磁共振测量的质子弛豫率。自旋-自旋弛豫速率 R2 用于估计碳链长度。该方法针对主线性碳链平均长度不同的一组样品进行了检验。使用四种不同的脂肪酸以及这些脂肪酸中的两种、三种或四种的混合物制备样品。已知值和测量值之间的相关系数等于0.994。基于弛豫理论，简要显示了弛豫速率与碳链长度之间的线性相关性，这证实了实验结果。所开发的确定碳链长度的方法具有鲁棒性和快速性，当在实际工业环境中在线使用该方法时，这是显着的优势。