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Determining the methanol partition coefficient (K ow ) in octanol/water system is important to assess the risk of its impact to humans and the environment. In this paper, we report a novel method for the determination of the K ow of methanol with headspace gas chromatography (HS-GC), using a three-phase equilibrium-based phase ratio variation approach. Three headspace vials with different phase ratios [(1) 0.2 mL of water plus 3 mL of octanol, (2) 1 mL of water plus 3 mL of octanol and (3) 1 mL of water plus 10 mL of octanol] were used in the experiment. After pre-standing at 25 °C for > 10 h and equilibrating in the headspace oven at a temperature of interest for additional 25 min, the methanol signals of the vapor phase (i.e., the headspace) in these vials were measured by HS-GC, from which the K ow of methanol can be calculated based on the established equations. The results showed that the method has good precision (within 0.06 log unit in standard deviation) and acceptable accuracy (with method error within 0.5 log unit). A correlation between the K ow of methanol and temperature extrapolated the K ow values in a temperature range of interest. The present method represents a simple and in-situ approach for the determination of the K ow of methanol and is also suitable to be applied to other volatile compounds., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

This paper reported a new method for the determination of the water distribution in sludge. It was based on a multiple headspace extraction (MHE) procedure to step-wise remove the water vapor from a closed vial containing a sludge sample, followed by a gas chromatographic measurement (GC). By plotting the GC signal of water vapor vs. the headspace extraction number, three different trend lines from the profile can be observed. From which two transition points can be determined and thus the stages for the free water, capillary water, and adsorption water release can be divided. Based on the sum of GC peak areas ate each stage, the content of these water types in the sludge can be calculated through a method calibration. The results showed that the MHE-GC method has a better measurement repeatability (RSD < 18.6%) and sensitivity (limit of quantitation = 0.028%) than the thermal drying method (used as a reference method). There was also a good agreement between the MHE-GC and the reference method on the free water and capillary water analysis. Moreover, the results on the adsorption water and bound water testing by the present method is more justifiable than the reference method., Competing Interests: Declaration of Competing Interest No conflict of interest exists in the submission of this manuscript, and the manuscript is approved by all authors for publication. I would like to declare on behalf of my co-authors that the work described was original research that has not been published previously, and not under consideration for publication elsewhere. All the authors listed have approved the manuscript that is enclosed., (Copyright © 2020. Published by Elsevier B.V.)

This work reports on a method for the accurate determination of fiber water-retaining capability at process conditions by headspace gas chromatography (HS-GC) method. The method was based the HS-GC measurement of water vapor on a set closed vials containing in a given amount pulp with different amounts of water addition, from under-saturation to over-saturation. By plotting the equilibrated water vapor signal vs. the amount of water added in pulp, two different trend lines can be observed, in which the transition of the lines corresponds to fiber water-retaining capability. The results showed that the HS-GC method has good measurement precision (much better than the reference method) and good accuracy. The present method can be also used for determining pulp fiber water-retaining capability at the process temperatures in both laboratory research and mill applications., (Copyright © 2016 Elsevier B.V. All rights reserved.)

This paper describes a new method for the rapid determination of the moisture content in paper materials. The method is based on multiple headspace extraction gas chromatography (MHE-GC) at a temperature above the boiling point of water, from which an integrated water loss from the tested sample due to evaporation can be measured and from which the moisture content in the sample can be determined. The results show that the new method has a good precision (with the relative standard deviation <0.96%), high sensitivity (the limit of quantitation=0.005%) and good accuracy (the relative differences <1.4%). Therefore, the method is quite suitable for many uses in research and industrial applications., (Copyright © 2016 Elsevier B.V. All rights reserved.)

This study reports a new headspace gas chromatographic method (HS-GC) for the determination of water solubility of low volatility liquid organic compounds (LVLOs). The HS-GC analysis was performed on a set of aqueous solutions containing a range of concentrations of toluene-spiked (as a tracer) LVLOs, from under-saturation to over-saturation. A plot of the toluene tracer GC signal vs. the concentration of the LVLO results in two lines of different slopes that intersect at the concentration corresponding to the compound's solubility in water. The results showed that the HS-GC method has good precision (RSD <6.3%) and good accuracy, in which the relative deference between the data measured by the HS-GC method and the reference method were within 6.0%. The HS-GC method is simple and particularly suitable for measuring the solubility of LVLOs at elevated temperatures. This approach should be of special interest to those concerned about the impact of the presence of low-volatility organic liquids in waters of environmental and biological systems., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Alkylphenol polyethoxylates (APEO), surfactants used in the production of textiles, have the potential to move from the fabric to the skin of the person wearing the clothes, posing an inherent risk of adverse health consequences. Therefore, the textile industry needs a fast, robust method for determining aqueous extractable APEO in fabrics. The currently-favored HPLC methods are limited by the presence of a mixture of analytes (due to the molecular weight distribution) and a lack of analytical standards for quantifying results. As a result, it has not been possible to reach consensus on a standard method for the determination of APEO in textiles. This paper addresses these limitations through the use of reaction-based head space-gas chromatography (HS-GC). Specifically, water is used to simulate body sweat and extract APEO. HI is then used to react the ethoxylate chains to depolymerize the chains into iodoethane that is quantified through HS-GC, providing an estimate of the average amount of APEO in the clothing. Data are presented to justify the optimal operating conditions; i.e., water extraction at 60°C for 1h and reaction with a specified amount of HI in the headspace vial at 135°C for 4h. The results show that the HS-GC method has good precision (RSD<10%) and good accuracy (recoveries from 95 to 106%) for the quantification of APEO content in textile and related materials. As such, the method should be a strong candidate to become a standard method for such determinations., (Copyright © 2015 Elsevier B.V. All rights reserved.)

A novel method for the determination of the diffusion coefficient (D) of methanol in water and olive oil has been developed. Based on multiple headspace extraction gas chromatography (MHE-GC), the methanol released from the liquid sample of interest in a closed sample vial was determined in a stepwise fashion. A theoretical model was derived to establish the relationship between the diffusion coefficient and the GC signals from MHE-GC measurements. The results showed that the present method has an excellent precision (RSD<1%) in the linear fitting procedure and good accuracy for the diffusion coefficients of methanol in both water and olive oil, when compared with data reported in the literature. The present method is simple and practical and can be a valuable tool for the determination of the diffusion coefficient of volatile analyte(s) into food simulants from food and beverage packaging material, both in research studies and in actual applications., (Copyright © 2015 Elsevier B.V. All rights reserved.)

This paper reports on the development of a new headspace analytical technique that is based on water removal by hydrate formation (WRHF). By adding anhydrous salt, the liquid water in an aqueous sample will be removed leaving behind volatile analytes that are fully vaporized at temperatures well below their boiling points. With WRHF, the amount of sample in the headspace can be significantly increased, thereby dramatically improving the detection sensitivity. The technique reduces the risk of possible column damage in gas chromatography (GC) systems. The technique was applied to the determination of phenol at different stages of a coking wastewater treatment plant. The results showed that up to mL-levels of sample solution can be used in WRHF HS-GC analysis when 5g of CaCl2 were used as the anhydrous salt. The detection sensitivity for phenol content was 500 times greater than that in earlier HS-GC work that did not incorporate hydrate formation. The proposed WRHF headspace analysis technique is simple and practical, making it a useful tool for quantifying low concentrations of volatile analytes in aqueous samples., (Copyright © 2014 Elsevier B.V. All rights reserved.)

A hybrid organic-inorganic material based on vermiculite was prepared to remove diethyl phthalate (DEP) from aqueous solution. Natural vermiculite was activated with HCl to improve the specific surface area and was then modified by silanization using trimethylchlorosilane. Organovermiculite prepared by ion exchange with hexadecyl trimethylammonium bromide (HDTMAB) was also tested for comparison. The leaching of 2 mol L(-1) HCl at 80°C increased the specific surface area of vermiculite from 14.4 to 500.0m(2)g(-1), and the average pore-diameter was decreased from 7.90 nm to 2.75 nm. Fourier transform infrared spectroscopy (FTIR) spectra indicated that trimethysilyl groups were grafted covalently on the surface of acid vermiculites. The specific surface area of trimethylchlorosilane-modified acid vermiculites (TMAVs) (355.4 m(2) g(-1)) was much larger than that of organovermiculite (6.0 m(2) g(-1)). The isotherm adsorption experiments of DEP showed that TMAVs exhibited linear isotherms, suggesting that the uptake of DEP was controlled by partitioning mechanism. The maximal partition coefficient (K(d)) of TMAVs was 3.1 times higher than that of organovermiculite, implying that TMAVs had stronger organic affinity than organovermiculite. The results demonstrate that the adsorption capacity and mechanism of organoclays were controlled by the specific surface area and organic loading, whereas the length of alkyl chain of organic modifier was not the key factor., (Copyright © 2011 Elsevier Inc. All rights reserved.)

The present work reports on a method for the determination of hydrophobic degree of paper packaging material by tracer-assisted headspace gas chromatography. The method was based on adding 40 μL of methanol-water drop on the paper surface for 20 s. After removing the excess water by turning the sample vertically, the sample is placed in a vial and the amount of residual tracer attached on the material surface was accurately quantified by full evaporation headspace gas chromatography. The results show that the present method has a good precision (less than 4.1 %). The present method is simple and accurate and it can be an efficient tool for testing the hydrophobic degree of paper packaging material in batch. [ABSTRACT FROM AUTHOR]

The study investigated the impact of fiber initial water content (FIWC) on the poplar APMP fibers' water retention capacity. In this work, FIWC refers to the water content of samples before drying, obtained by the different centrifugation forces at the given conditions. The results showed that the water retention value of pulps increased with the decrease in FIWC when it was below 60%, with or without thermal drying. An analysis of the fibers showed a slight decrease in the average pore size took place with the decrease in FIWC for the never-dried pulps. Based on these findings, a mechanism of the impact of FIWC on the poplar APMP water retention capacity was proposed. The present work will be helpful for a better understanding of the thermal drying-induced hornification. [ABSTRACT FROM AUTHOR]

This paper reports on a high-throughput headspace gas chromatographic method (HS-GC) for the determination of nitrite content in water sample, based on GC measurement of cyclohexene produced from the reaction between nitrite and cyclamate in a closed vial. The method has a relative standard deviation of <3.5%; The differences between the results of the nitrite measurements obtained by this method and those of a reference method were less than 5.8% and the recoveries of the method were in the range of 94.8–102% (for a spiked nitrite content range from 0.002 to 0.03 mg/L). The limit of detection of the method was 0.46 μg L −1 . Due to an overlapping mode in the headspace auto-sampler system, the method can provide an automated and high-throughput nitrite analysis for the surface water samples. In short, the present HS-GC method is simple, accurate, and sensitive, and it is very suitable to be used in the batch sample testing. [ABSTRACT FROM AUTHOR]

Abstract: The paper reports partial oxidative gasification of phenol for hydrogen in supercritical water (SCW) at lower temperature (<753K), at which cleavages of aromatic ring occur difficultly and tend to undesirable polymerization. The results showed that O2 is effective to gasification of phenol in SCW. ∼76% of phenol was gasified and 2.7mol/mol of hydrogen was produced within 180s with Na2CO3 as catalyst at the selected process conditions, a molar ratio of oxygen-to-phenol, 7.5–1, 723K, and 24MPa. It was found that unstable opening-rings products oxalic and maleic acid and stable dimmerization compounds in liquid water were formed during partial oxidation process. The process also indicated phenol was rapidly converted, and some opening-rings products were slowly gasified, which also confirmed oxygen served as effective reactant for ring-opening. Based on the given reaction conditions, a treatment process using a real wastewater from coking industry was performed. The data showed that the present technology provides an effective way to gasification of phenol wastewater for high-value energy utilization. [Copyright &y& Elsevier]