Online Continuous Trace Process Analytics Using Multiplexing Gas Chromatography.
Marco R WunschRudolf LehnigOliver TrappPublished in: Analytical chemistry (2017)
The analysis of impurities at a trace level in chemical products, nutrition additives, and drugs is highly important to guarantee safe products suitable for consumption. However, trace analysis in the presence of a dominating component can be a challenging task because of noncompatible linear detection ranges or strong signal overlap that suppresses the signal of interest. Here, we developed a technique for quantitative analysis using multiplexing gas chromatography (mpGC) for continuous and completely automated process trace analytics exemplified for the analysis of a CO2 stream in a production plant for detection of benzene, toluene, ethylbenzene, and the three structural isomers of xylene (BTEX) in the concentration range of 0-10 ppb. Additional minor components are methane and methanol with concentrations up to 100 ppm. The sample is injected up to 512 times according to a pseudorandom binary sequence (PRBS) with a mean frequency of 0.1 Hz into a gas chromatograph equipped with a flame ionization detector (FID). A superimposed chromatogram is recorded which is deconvoluted into an averaged chromatogram with Hadamard transformation. Novel algorithms to maintain the data acquisition rate of the detector by application of Hadamard transformation and to suppress correlation noise induced by components with much higher concentrations than the target substances are shown. Compared to conventional GC-FID, the signal-to-noise ratio has been increased by a factor of 10 with mpGC-FID. Correspondingly, the detection limits for BTEX in CO2 have been lowered from 10 to 1 ppb each. This has been achieved despite the presence of detectable components (methane and methanol) with a concentration about 1000 times higher than the target substances. The robustness and reliability of mpGC has been proven in a two-month field test in a chemical production plant.
Keyphrases
- gas chromatography
- mass spectrometry
- tandem mass spectrometry
- high resolution mass spectrometry
- carbon dioxide
- gas chromatography mass spectrometry
- big data
- machine learning
- heavy metals
- loop mediated isothermal amplification
- label free
- real time pcr
- solid phase extraction
- liquid chromatography
- drinking water
- deep learning
- air pollution
- high resolution
- physical activity
- ionic liquid
- high throughput
- signaling pathway
- healthcare
- anaerobic digestion
- simultaneous determination
- computed tomography
- health information
- social media
- room temperature
- risk assessment
- artificial intelligence
- magnetic resonance imaging
- sensitive detection
- data analysis