Method Validation of Gas Chromatography and Stability Study for Analysis of Standard Gas Mixtures of Carbon Dioxide in Nitrogen Matrix

Currently, precise and accurate measurements of CO₂ emissions are essential for obtaining valid and reliable monitoring data, which serve as the basis for decision-making by environmental policy makers. In this study, method validation was carried out to measure CO₂ at emission concentrations (1000 μmol/mol and 2.8% mol/mol) using gas chromatography with a thermal conductivity detector (GC-TCD). Various parameters of method validation, such as selectivity, limit of detection (LoD), limit of quantification (LoQ), accuracy, precision, linearity, and ruggedness, were investigated thoroughly. The results showed that the GC-TCD method demonstrated good repeatability and intermediate precision, with a % relative standard deviation less than 0.2%, while the bias method had a value between ± 2σ (σ: precision of laboratory result). The relative expanded uncertainty estimations are approximately 0.5% and 0.8% for CO₂ measurements of 2.8% mol/mol and 1000 µmol/mol, respectively. The validated in-house method of GC-TCD is found to be precise, accurate, and fit for the purpose of measuring CO₂ gases in the N₂ matrix and capable of quantifying CO₂ emission levels (1000 µmol/mol and 2.8% mol/mol).