Journal
ACS SENSORS
Volume 7, Issue 1, Pages 304-311Publisher
AMER CHEMICAL SOC
DOI: 10.1021/acssensors.1c02344
Keywords
preconcentrator; selective detection; gas sensor; volatile organic compounds; nanoporous silica
Funding
- Cambridge Trust
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The study developed a novel thermal separator system combined with a photoionization detector, which can selectively detect specific VOC compounds in a mixture. By adsorbing VOCs in nanoporous silica at 5 degrees C and then detecting them during the heating process up to 70 degrees C, the separation and detection of isopropanol and 1-octene in a mixture was successfully achieved.
The selective detection of individual hazardous volatile organic compounds (VOCs) within a mixture is of great importance in industrial contexts due to environmental and health concerns. Achieving this with inexpensive, portable detectors continues to be a significant challenge. Here, a novel thermal separator system coupled with a photoionization detector has been developed, and its ability to selectively detect the VOCs isopropanol and 1octene from a mixture of the two has been studied. The system includes a nanoporous silica preconcentrator in conjunction with a commercially available photoionization detector (PID). The PID is a broadband total VOC sensor with little selectivity; however, when used in conjunction with our thermal desorption approach, selective VOC detection within a mixture can be achieved. VOCs are adsorbed in the nanoporous silica over a 5 min period at 5 degrees C before being desorbed by heating at a fixed rate to 70 degrees C and detected by the PID. Different VOCs desorb at different times/temperatures, and mathematical analysis of the set of PID responses over time enabled the contributions from isopropanol and 1-octene to be separated. The concentrations of each compound individually could be measured in a mixture with limits of detection less than 10 ppb(v) and linearity errors less than 1%. Demonstration of a separation of a mixture of chemically similar compounds, benzene and o-xylene, is also provided.
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