Phase ratio variation approach for the study of partitioning behavior of volatile organic compounds in polymer sample bags: Nalophan case study

Abstract

Sorption of volatile organic compounds on the inner surface of polymer sampling bags leads to important underestimations of the real headspace concentration. Introducing a wide range of volatiles in a two-phase system containing Nalophan revealed that recoveries decreased down to 57 % in a period of 22 h. In this work, a phase ratio variation approach is investigated to quantify the degree of scalping, and thus enabling to compensate for sorption phenomena. This method requires limited measurements, without the need for time-consuming calibrations. By spiking identical amounts of volatiles in three two-phase systems, each having unique polymer volume/mass ratios β (β 1 = 0, β 2 = 80.9, β 3 = 161.9), individual partitioning coefficients could be experimentally determined for a wide range of compounds. Additionally, a correlation was found between these partitioning coefficients and the liquid molar volume for a number of aliphatic, aromatic, and oxygenated compounds.

Mechanisms of Loss of Agricultural Odorous Compounds in Sample Bags of Nalophan, Tedlar, and PTFE

“…Assuming that the main loss is caused by physical adsorption and the surface area and temperature are constant in each bag, some correlation to the vapor pressure is expected. Defining a partitioning coefficient ( K ), where C ads is the amount of compound adsorbed (lost), C g is the concentration in the gas phase, and A is the surface area of the bag (Pankow and Bidleman, 1992; Van Durme and Werbrouck, 2015): …”

Analyses of odours from concentrated animal feeding operations: A review

“…Many works have been focused on the factors that can modify the gaseous sample inside the bag and how these can affect the following analysis. Examples of factors that can lead to serious mistakes are the release of contaminants from the inner surface of the bag to the sample, chemical instability of the sample, sorption of the molecules of the sample on the inner surface of the polymer, storage time and temperature, light exposure of the bag and humidity of the air sample (Boeker et al, 2014;Capelli et al, 2014;Ghimenti et al, 2015;Ghosh et al, 2011;Hansen et al, 2011;Le et al, 2013Le et al, , 2015Szyłak-Szydłowski, 2015;Trabue et al, 2006;Van Durme and Werbrouck, 2015;Van Harreveld et al, 1999;Van Wang et al, 1996;Zarra et al, 2012).…”

Optimal experimental designs for estimating Henry's law constants via the method of phase ratio variation

“…The field was formalized beginning with Kiefer (1959)'s paper which laid the foundations for further work. Equivalence theorems for # Authors Solutes Solvent 1 van Durme and Werbrouck (2015) fifty indoor VOCs Nalophan 2 Benjamin et al (2011) five VOCs Oil-in-water emulsions 3 Gao et al (2009) BTEX and chlorin-Cyclodextrin aqueous ated solvents solutions 4 Kechagia et al (2008) two monomers Water 5 Lei et al (2007) alkanols Water 6 Atlan et al (2006) aroma compound Propylene glycol 7 Jouquand et al (2004) aroma compound Cyclodextrin aqueous solutions 8 Chai and Zhu (1998) methanol Water 9 Peng and Wan (1998) and BTEX and chlorin-Water and saline Peng and Wan (1997) ated solvents waters 10 Ettre et al (1993) four VOCs Water optimality criteria were to follow. Modern goals include variable screening, response surface exploration, system optimization and optimal inference (Hu, 2014) which is our focus here.…”