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

Separations ◽  
2022 ◽  
Vol 9 (1) ◽  
pp. 15
Author(s):  
Oleg V. Rodinkov ◽  
Alexey Y. Pisarev ◽  
Leonid N. Moskvin ◽  
Aleksandra S. Bugaichenko ◽  
Pavel N. Nesterenko

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.

Chemija ◽  
2019 ◽  
Vol 30 (4) ◽  
Author(s):  
Birutė Bugelytė ◽  
Karolina Ilonina ◽  
Vilius Poškus ◽  
Vida Vičkačkaitė

Direct and headspace gas chromatographic analysis is compared for the determination of lactic, oxalic, succinic, malic and citric acids. For better chromatographic behaviour, prior to GC analysis carboxylic acids were derivatized using BSTFA as a silylation reagent. Three solvents – acetone, diethyl ether and dimethylformamide – were tested as a derivatization medium and DMF was considered as the best. Derivatization conditions were optimized and analytical characteristics of the direct gas chromatographic determination of analytes in solutions were determined. The method was applied for the determination of citric acid in food. For the analytes dissolved in DMF, the headspace gas chromatographic determination was not sensitive enough. Concentrations of the derivates in the headspace were very low, thus the limits of detection were high and the method was not of practical use. On the other hand, headspace gas chromatography can be applied for identifying of carboxylic acids in solid samples.


2019 ◽  
Vol 2019 ◽  
pp. 1-6 ◽  
Author(s):  
Xiaotao Zhang ◽  
Ruoning Wang ◽  
Li Zhang ◽  
Jianke Wei ◽  
Yibin Ruan ◽  
...  

A method for simultaneous determination of acetaldehyde, propionaldehyde, acrolein, and crotonaldehyde in gas phase of cigarette mainstream smoke by headspace gas chromatography-mass spectrometry was developed and validated. Gas phase components of mainstream cigarette smoke were extracted with methanol, and then the samples were separated on a DB 624 (60 m, 0.32 mm x 1.8 mm) column, analyzed with headspace gas chromatography-mass spectrometry, and quantified by isotope internal standard. The linearities of acetaldehyde, propionaldehyde, acrolein, and crotonaldehyde were good (R2>0.992). The recoveries of acetaldehyde, propionaldehyde, acrolein, and crotonaldehyde were between 78.5% and 115%. The relative standard deviations were less than 10%. The limits of detection and limits of quantitation were 0.014 μg/cigarette ~0.12 μg/cigarette and 0.045 μg/cigarette ~0.38 μg/cigarette, respectively. The method had advantage of high sensitivity, it did not require derivatization of 2,4-dinitrophenylhydrazine and avoided a large number of adverse reactions during the process of derivation to improve the accuracy of result, and it was suitable for quantitative analysis of four aldehydes in gas phase of cigarette mainstream smoke.


Energies ◽  
2020 ◽  
Vol 13 (9) ◽  
pp. 2262 ◽  
Author(s):  
Robert Hren ◽  
Aleksandra Petrovič ◽  
Lidija Čuček ◽  
Marjana Simonič

Pretreatment of waste materials could help in more efficient waste management. Various pretreatment methods exist, each one having its own advantages and disadvantages. Moreover, a certain pretreatment technique might be efficient and economical for one feedstock while not for another. Thus, it is important to analyze how parameters change during pretreatment. In this study, two different pretreatment techniques were applied: thermal at lower and higher temperatures (38.6 °C and 80 °C) and biological, using cattle rumen fluid at ruminal temperature (≈38.6 °C). Two different feedstock materials were chosen: sewage sludge and riverbank grass (Typha latifolia), and their combinations (in a ratio of 1:1) were also analyzed. Various parameters were analyzed in the liquid phase before and after pretreatment, and in the gas phase after pretreatment. In the liquid phase, some of the parameters that are relevant to water quality were measured, while in the gas phase composition of biogas was measured. The results showed that most of the parameters significantly changed during pretreatments and that lower temperature thermal and/or biological treatment of grass and sludge is suggested for further applications.


Chemija ◽  
2018 ◽  
Vol 29 (3) ◽  
Author(s):  
Birutė Bugelytė ◽  
Rima Jonkutė ◽  
Vida Vičkačkaitė

Headspace gas chromatographic analysis is suggested for the determination of acetic and propionic acids in aqueous media. Derivatization of the acids was accomplished by tributyl borate. The derivatization and headspace extraction were coupled into a single step. Analytical characteristics of the suggested technique at the optimized derivatization/headspace extraction conditions were determined. The technique was applied for the analysis of bakery products, ketchup, tomato paste and kefir.


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