Development of miniaturized autonomous and versatile gas chromatograph for Volatile Organic Compounds monitoring using Nano-Gravimetric-Detector

Abstract

Environmental monitoring and air quality survey during long-term field campaign tests, especially in low-accessibility or extreme environments, requires robust, standalone and autonomous analyzer with low gas consumption and minimal human intervention. The current states of art emphasize the need to develop miniaturized GC based on novel detectors that offers the best compromise between carrier gas consumption, detection limits and panel of measured VOCs. This work presents the development and optimization of MAVERIC, a miniaturized and autonomous Gas Chromatograph system coupled to an innovative Nano Gravimetric Detector (NGD) based on NEMS (nano-electromechanical-system) resonator. A homemade software is developed to control the instrument as well as the electronics modules. The system operates at low flow rate (2 mL.min⁻¹) of helium used as carrier gas, and allows the measurements of VOCs from C₆ to C₁₀ in less than 30 min. A mixture of isoprene, benzene, toluene and α-pinene is used to optimize experimental conditions. Under optimal conditions, the detection limit, the stability, the repeatability and the linearity of the analytical system are assessed. A detection limit of sub-ppb to few ppt level was determined for C₆ and C₉ compounds, respectively. The lowest detection limit corresponds to the highest molecular weight compounds due to NGD sensitivity at ambient temperature. The system is standalone, portable, robust and equipped with 4G connection that allows remote control of the instrument and easy data export. It is very adapted for a long period field campaign test, environmental monitoring and air quality survey outdoors and in low-accessibility or extreme environments.