Monitoring & metering


GAS CHROMATOGRAPHY SENSORS ADDRESS ENVIRONMENTAL MONITORING NEEDS


This article from Linlong Zhang, field applications engineer at Analog Devices, outlines the working principles and components of a gas chromatography sensor system for applications in environmental quality monitoring. It describes how gas chromatography can precisely analyse compounds related to water and soil contamination. The article discusses the key components of a gas chromatography system, including the air inlet, temperature control, detector, and power supply subsystems. It will also provide recommendations for low noise amplifiers, analogue-to-digital converters (ADCs), voltage references, and power management ICs that can enable high accuracy measurements.


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xhaust gas monitoring plays an important role in environmental protection. As a result of industrial waste, some volatile organic compounds will be dispersed into the air, which will have an impact on the natural environment and human health.


There is a strong focus on environmental monitoring to reduce these emissions. However, traditional sensor systems are unable to meet the speed and accuracy requirements needed today. To compound the challenge, environmental monitoring systems also need to be enhanced to address high precision demands.


This article provides an overview of emerging gas chromatography technology as well as available solutions.


BASIC GAS CHROMATOGRAPHY THEORY A gas chromatography system mainly consists of a gas inlet system, autosampler system, separation system, control system, detector system, and data processing. The block diagram of gas chromatography is depicted in Figure 1. The carrier gas of gas chromatography is the mobile phase, and the sample under test is named stationary phase including solid and liquid mixture. The stationary phase is separated with gas flowing movement to leave the chromatographic column in sequence. Afterward, it enters the detector and generates the ion flow signal. These small signals are reflected to different components of the chromatogram by amplifying to a suitable amplitude on a recorder. The separation process


Figure 1. A diagram of a gas chromatograph system.


Figure 2. The process of separation. August 2024 Instrumentation Monthly


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