Abstract
In this study, a novel approach in headspace gas chromatographic analysis using the selective absorption of the gas extractant during concentration of the analytes was developed. The carbon dioxide used as the gas extractant was removed from the sample flow by passing it through a column packed with microdispersed sodium hydroxide granules. The analytical capabilities of the suggested method were illustrated by the determination of aliphatic and aromatic hydrocarbons in water. We established that this method allows the preconcentration of analytes in the gas phase to be increased proportionally to the volume ratios of the gas extractant before and after absorption, while the analyte limits of detection decrease 30-fold. For example, benzene can be detected in water at a concentration of 0.5 μg/L.
Highlights
The general method of determining volatile organic compounds (VOCs) in aqueous solutions is headspace analysis (HSA), which is based on various modes of the gas-phase extraction of analytes and their gas chromatographic (GC) determination [1,2,3,4,5,6]
HSA is a nonalternative method for the analysis of hydrocarbons, solving problems in the areas of sanitation and environmental control, in particular, the use of headspace analysis in the case of highly toxic aromatic hydrocarbons dissolved in water, the determination of which requires highly efficient concentration methods
The aim of the present work was the development of a new version of sensitive HSA exploring the additional preconcentration of VOCs using the selective trap of the gas extractant
Summary
The general method of determining volatile organic compounds (VOCs) in aqueous solutions is headspace analysis (HSA), which is based on various modes of the gas-phase extraction of analytes and their gas chromatographic (GC) determination [1,2,3,4,5,6]. By considering the partition of VOCs between the aqueous and the gas phase, the gas-phase extraction isolation of analytes enables an increase in the sensitivity of the analysis by one to three orders of magnitude compared to the direct injection of aqueous samples (without enrichment) into the gas chromatograph. A combination of HSA with gas-phase adsorption is often used for the preconcentration of analytes. The preconcentration of VOCs using static gas-phase extraction, known as headspace solid-phase microextraction (HS SPME) [7,8,9,10,11], dynamic [9,12,13], and continuous gas-phase extraction [14,15,16], can be achieved
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