Comparison of sample concentration methods and correlation chromatography for polymer dynamic head-space studies

Abstract

SummaryGas chromatography has been used to study the kinetics of evolution of volatiles from polypropylene samples (at 70 ~ Correlation chromatography (CC) and the trapping of volatiles on Tenax sorbents and activated charcoal were employed to improve the detector signal. As a reference, the kinetics of gas evolution was studied by making a series of direct single injections of polymer head-space gas on a GC column. The results of trapping differed from those obtained by single injection. However, the data from single injections and CC were in good agreement. The CC method was found to offer far more operator convenience for dynamic head-space analysis than sample trapping, being less subject to operator errors.

A method to determine volatile contaminants in polyethylene terephthalate (PET) packages by HDC-GC-FID and its application to post-consumer materials

“…The techniques for the extraction of the volatile compounds absorbed by the packaging material include the use of solvents, concentration of the extract, and subsequent determination by Gas Chromatography (GC) using a flame ionisation (FID) or Mass Spectrometry (MS) detector (LEBOSSÉ; DUCRUET; FEIGENBAUM, 1997;PAIK, 1992;REYNIER et al, 2004;FREIRE et al, 1998;KALJURAND;SMIT, 1994;NIELSEN, 2005). Currently, the most used extraction systems involve headspace analysis.…”

“…There are many variations to this analytical technique such as the direct analysis of the headspace, and static and dynamic concentration of the headspace using traps consisting of porous polymers, especially tenax (FRANZ;MAUER;WELLE, 2004;van WILLIGE et al, 2003;KALJURAND;SMIT, 1994;HAKKARAINEN;GRONING;ALBERTSSON, 2003;SOTO-VALDEZ;GRAMSHAW;VANDENGURG, 1997;NIELSEN, 2005;NONGONIERMA et al, 2006). Recent advances include automatic systems that allow the coupling of the headspace sampler to the gas chromatograph injector, known as the purge and trap injection system (LEBOSSÉ; DUCRUET; FEIGENBAUM, 1997;WEZL;LANKMAYR, 2002;REYNIER et al, 2004;VILLBERG;VEIJANEN;GUSTAFSSON, 1998;KALJURAND;SMIT, 1994). The solid phase micro-extraction system is a recent modification introduced for the analysis of matrixes such as packaging materials (ZHANG; PAWLISZYN, 1993;EZQUERRO;PONS;TENA, 2003;PAWLISZYN, 1997).…”

Correlation capillary zone electrophoresis, a novel technique to decrease detection limits

“…This S/N ratio improvement is also known as the multiplex advantage. Recently it was demonstrated that the use of correlation techniques shows better results in comparison with pre-concentration for head-space GC [6]. This suggests the application of the correlation techniques in CZE, resulting in correlation capillary zone electrophoresis (CCZE).…”

Contaminantes voláteis provenientes de embalagens plásticas: desenvolvimento e validação de métodos analíticos

“…6,[28][29][30][31][32][33] Alguns autores sugerem que o aumento da concentração de analitos pode ser obtido por destilação ou evaporação a vácuo. 20,28,34,35 Para materiais de embalagem, o uso de técnicas de extração de voláteis está associado a avaliações qualitativas e quantitativas dos processos de permeação, sorção e migração, envolvendo medidas de coeficientes de partição, constantes de difusão e determinação de curvas de sorção para substâncias permeantes.…”

“…Esta técnica é conhecida por análise do headspace. 15,29,37,38 As variações mais conhecidas desta técnica incluem o método do headspace estático e o método do headspace dinâmico (purge-and-trap). 33,39 No modo estático, a amostra é armazenada e selada em um frasco hermético e os analitos voláteis são coletados no headspace do frasco após equilíbrio de volatilização.…”