Inst. of Agrophysics, Polish Academy of Sciences, Do´swiadczalna 4, 20-290, Lublin, Poland.
J Food Sci. 2019 Aug;84(8):2077-2085. doi: 10.1111/1750-3841.14701. Epub 2019 Jul 24.
Volatile organic compounds (VOCs) are natural markers useful in rapid assessment of adverse changes occurring in biological material. The use of an electronic nose seems to be a good, fast, and cheap method to determine particular VOCs. This paper presents a new method determination for VOCs and their concentration based on three sensorgram parameters: maximum of normalized sensor response, reaction time, and cleaning time measured from the end of the test to the half value of the maximum of normalized sensor response. The novelty of the method consists in the use for the first time of two parameters: reaction time and cleaning time measured from the end of the test to the half value of the maximum of normalized sensor response. The VOC sensorgrams at different VOC concentrations (26 to 3,842 ppm) were measured by an electronic nose Food Volatile Compound Analyzer (Agrinose) equipped with eight metal oxide semiconductor sensors dedicated to detect different gases. In the present studies, only six sensors that best respond to the VOCs were used. The highest responses to VOCs were obtained for two sensors-TGS2602 and AS-MLV-P2. The results showed that the dependence between the sensorgram parameters on VOC concentration was well described by a logarithmic curve in the whole range of concentrations. Detailed analysis revealed that the cleaning time increases with an increase in the number of carbon atoms in aliphatic molecules. The principal component analysis (PCA) was used to verify the utility of the new three parameters method in VOCs differentiation. The PCA analysis of these parameters showed that maximum of the normalized sensor response alone, which has been used for identification of particular VOCs so far, could not be regarded as a good parameter used for this purpose. Application of all the three parameters gave the best results in VOC identification. The research indicates that the use of three parameters of a volatile compound instead of only one parameter can allow precise determination of substances. Moreover, the results indicate that the analyzed parameters depend on the chemical structure of VOCs.
挥发性有机化合物（VOCs）是快速评估生物材料中发生的不利变化的有用天然标志物。使用电子鼻似乎是一种很好、快速且廉价的方法来确定特定的 VOCs。本文提出了一种新的基于三个传感器图谱参数的 VOC 及其浓度的测定方法：归一化传感器响应的最大值、反应时间和从测试结束到归一化传感器响应最大值的一半的清洁时间。该方法的新颖之处在于首次使用了两个参数：从测试结束到归一化传感器响应最大值的一半的反应时间和清洁时间。使用配备了八个金属氧化物半导体传感器的电子鼻食品挥发性化合物分析仪（Agrinose）测量了不同 VOC 浓度（26 至 3842 ppm）下的 VOC 传感器图谱，这些传感器专门用于检测不同的气体。在本研究中，仅使用了对 VOC 响应最佳的六个传感器。TGS2602 和 AS-MLV-P2 两个传感器对 VOC 的响应最高。结果表明，传感器图谱参数与 VOC 浓度之间的关系在整个浓度范围内很好地用对数曲线描述。详细分析表明，清洁时间随脂肪族分子中碳原子数的增加而增加。主成分分析（PCA）用于验证新的三个参数方法在 VOC 区分中的实用性。这些参数的 PCA 分析表明，迄今为止，仅用于识别特定 VOC 的归一化传感器响应最大值不能被视为用于此目的的良好参数。应用所有三个参数可以在 VOC 识别中获得最佳结果。研究表明，使用挥发性化合物的三个参数而不是仅一个参数可以更精确地确定物质。此外，结果表明，分析参数取决于 VOC 的化学结构。
