Volatile organic compounds (VOCs) in gas mixtures at trace level (nmol/mol) are routinely measured by chemical and biochemical laboratories as climate indicators, indoor air quality pollutants from building materials emissions, contaminants in food and beverages, and biomarkers in body fluids (blood, urine, breath) of occupational exposure or human diseases. Current analytical instruments used for measurements are gas chromatographs equipped with various injector and detector configurations. The assurance of measurement quality is done by using a huge amount of certified liquid VOC standard solutions (or gaseous VOC standard cylinders) with multiple dilutions to reach the required trace level. This causes high standard uncertainty in instrument calibrations, high cost, and high consumption of analysis and laboratory personal time. In this paper, we present the implementation of portable generators producing VOC gas standards at trace level for automatic and direct calibration of VOC detectors employed in various contexts, removing the need for preparation of matrix calibration standards in cylinders. Two compact devices in-house developed by two national metrology institutes—the Istituto Nazionale di Ricerca Metrologica (INRIM) and the Federal Institute of Metrology (METAS)—are here used to dynamically generate reference gas mixtures in an SI traceable way. The two devices are based on different technologies: diffusion and permeation, for INRIM and METAS, respectively. A metrological characterization is given and the practical implementation at chemical and biochemical laboratories is discussed.

Open image in new window

化学和生化实验室常规测量气体混合物中痕量水平（nmol / mol）的挥发性有机化合物（VOC）作为气候指标，建筑材料排放的室内空气质量污染物，食品和饮料中的污染物以及体液中的生物标志物（血液，尿液，呼吸）或职业病或人类疾病。当前用于测量的分析仪器是配备有各种进样器和检测器配置的气相色谱仪。测量质量的保证是通过使用大量经过认证的液态VOC标准溶液（或气态VOC标准气瓶）进行多次稀释以达到所需的痕量水平。这导致仪器校准中的高标准不确定性，高成本以及分析和实验室个人时间的高消耗。在本文中，我们介绍了便携式发生器的生产方法，该发生器以痕量水平生产VOC气体标准品，用于在各种情况下对VOC检测器进行自动和直接校准，从而无需在气瓶中准备基质校准标准品。这是由两个国家计量机构自行开发的两个紧凑型设备，即Istituto Nazionale di Ricerca Metrologica（INRIM）和联邦计量研究所（METAS），用于以SI可追溯的方式动态生成参考气体混合物。两种设备基于不同的技术：分别针对INRIM和METAS的扩散和渗透。给出了计量学表征，并讨论了在化学和生化实验室的实际实施。

在新窗口中打开图像