Sensitivity Increase in Headspace Analysis of Hydrocarbons in Water by Using Online Selective Elimination of Gas Extractant

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.

Preconcentration of Volatile Organic Compounds on Carbon Magnetic Sorbents in the Analysis of Air by Using the Configuration Change of the Sorbent Bed during the Transition from Sorption to Thermodesorption GC-FID

“…After that, the narrow tube is immediately placed in a gastight container or in a thermal desorber to prevent the possible loss of analytes. The thermal desorption includes heating the tube to a temperature of 250 • C, keeping it for 1 min at this temperature, then the desorbed analytes are displaced into the evaporator (injector) of the GC instrument (9) and undergo analysis in a carrier gas flow (7).…”

“…Expression (9) shows the possibility of an increase in the preconcentration rate by increasing the flow rate of the analyzed air through the sorption tube. This possibility can be realized by using wider columns of shorter lengths at the sorption stage.…”

“…Dynamic SPE is based on passing the analyzed gas through a tube with a sorbent, followed by the thermal desorption and the GC determination of the analytes [2,3,8]. Dynamic SPE is carried out using various porous polymer and carbonaceous adsorbents [9][10][11][12][13], including nanocarbon materials with a high specific surface area and hydrophobicity [14][15][16]. It should be noted that hydrophobic polymer adsorbents have a significantly lower sorption capacity as compared to carbon sorbents [13].…”

Determination of pollutions in the surface of water samples from Ogbajarajara river, Nigeria by spectrophotometer and atomic absorption spectrometry before evaluation of health risk assessment

“…Other activities are washing clothes, motorcycles, and cars, kitchen utensils, bathing, fishing, and road construction near the rivers. Recently many technologies such as the spectrophotometer [7], atomic absorption spectrometry [8], HPLC [9], gas chromatography [10], and electrochemistry were used for the determining of pollutions. The sole aim of this work is the determination of pollution in surface waters and the evaluation of human risk assessment due to the presence of heavy metals in surface water sources in this area.…”