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Zhang C.-Y.,South China University of Technology | Li L.-L.,South China University of Technology | Chai X.-S.,South China University of Technology | Barnes D.G.,National Paper Products Quality Supervision Inspection Center
Journal of Chromatography A | Year: 2014

This study reports on a rapid method for the determination of methanol in paper-based materials by alkaline extraction, coupled with headspace analysis. Methanol partition equilibria between solid-liquid phases and vapor-liquid phases were conducted in two separate containers, from which an equation for calculating the total methanol content in the original paper sample was derived. It was found that the extraction equilibrium of methanol from solid sample could be achieved within 5. min at room temperature using a high-speed disintegrator, and a subsequent neutralization step is an effective way to prevent methanol from being regenerated at high temperature during headspace equilibration. The results showed that the relative standard deviations for reproducibility tests were in the range of 1.86-6.03%, and the recoveries were in the range of 92.3-107%. The present method is simple and practical; it can be an efficient tool for quantifying the methanol content in paper-based materials and thus play an important role in the investigation of methanol migration behavior in food and beverage packaging. © 2014 Elsevier B.V. Source


Hu H.-C.,South China University of Technology | Tian Y.-X.,South China University of Technology | Chai X.-S.,South China University of Technology | Chai X.-S.,National Paper Products Quality Supervision Inspection Center
Analytical Sciences | Year: 2012

This study reports on a headspace gas chromatographic method (HS-GC) for the determination of formaldehyde in sanitary napkin samples. The method is based on the reaction of formaldehyde and sodium borohydride in a concentrated potassium carbonate solution (824 g/L), in which formaldehyde is quantitatively converted to methanol at 105 oC in 45 min. The methanol from the conversion is determined by HS-GC. The repeatability of the method had a relative standard deviation of less than 4.5%; the limit of quantification (LOQ) was 1.17 μg, and the recovery ranged from 96.8-106%. The present method is simple, rapid, and accurate. It is suitable for use in the batch testing for product quality control of tissue papers during the manufacturing process and in analysis of point-of-sale samples from commercial markets. © The Japan Society for Analytical Chemistry. Source


Zhang C.-Y.,South China University of Technology | Chai X.-S.,South China University of Technology | Chai X.-S.,National Paper Products Quality Supervision Inspection Center | Barnes D.G.,South China University of Technology
Fluid Phase Equilibria | Year: 2015

A novel method has been developed for the determination of the diffusion (D) and solid-air partition (Kd) coefficients of methanol in paper materials. The method used a solvent-assisted vapor absorption based headspace analysis technique to increase the driving force of the mass transfer process in the solid phase. Equations based on the established physical models described the process allowed the calculation of D and Kd of methanol in paper materials from the GC signals and experimental settings. The results showed that the amount of methanol transferred from the paper sheet can be significantly increased by the presence of the assisting triacetin. The solvent-assisted vapor absorption equilibrium can be obtained in 20min. The method also generated equations allowing for the calculation of D and Kd of methanol in paper materials at any temperature. The present method is simpler and quicker than the chamber methods that are in widespread use today and should be of special interest to those concerned about the impact of food and beverage packaging on human health. © 2015. Source


Hu H.-C.,South China University of Technology | Tian Y.-X.,South China University of Technology | Jin H.-J.,South China University of Technology | Chai X.-S.,South China University of Technology | And 2 more authors.
Journal of Agricultural and Food Chemistry | Year: 2013

This study reports on a method for determination of methanol in paper products by headspace gas chromatography (HS-GC). The method is based on the hydrolysis of the pulp or paper matrix, using a phosphoric acid solution (42.5%) as the medium at 120 °C in 5 h (excluding air contact) in order to release matrix-entrapped methanol, which is then determined by HS-GC. Data show that, under the given conditions of hydrolysis, no methanol was formed from the methoxyl groups in the material. Reproducibility tests of the method generated a relative standard deviation of <3.5%, with recovery in the range of 93.4-102%. The present method is reliable, accurate, and suitable for use in batch testing of the methanol content in paper-related materials. The method can play an important role in addressing food safety concerns that may be raised regarding the use of paper materials in food and beverage packaging. © 2013 American Chemical Society. Source


Wang Y.-F.,South China University of Technology | Wang Y.-F.,National Paper Products Quality Supervision Inspection Center | Chen K.-F.,South China University of Technology | Mo L.-H.,South China University of Technology | Zhou Z.-M.,South China University of Technology
Chung-kuo Tsao Chih/China Pulp and Paper | Year: 2012

The coagulation-flocculation method was used for the treatment of waste water from reconstituted tobacco sheet manufacturing by papermaking process. polyaluminum chloride (PAC) and polyferric sulfate (PFS) were used as coagulants, four kinds of polyacrylamide were used as coagulant aids. The effects of three factors, i.e. the dosage of coagulants, the dosage of coagulant aids and pH on the treatment efficiency were evaluated. The efficiencies of PAC and PFS on COD removal, ammonia nitrogen removal and suspended solids (SS) removal were similar, but the efficiency of PAC on color removal was obviously higher. Cationic polyacrylamide PAM4 with very high molecular weight and low charge density coupled with PAC was found to give the highest coagulation-flocculation efficiency. At the optimum pH of 6.5, the optimum PAC dosage of 500 mg/L, and the optimum PAM4 dosage of 5 mg/L, COD removal was found to be 70.8%, ammonia nitrogen removal was 84.8%, color removal was 72.3%, and SS removal was 98.5%. The PAC-PAM4 system did not result in residual aluminum production, contrarily, and removed most of aluminum in the effluent. UV absorption spectra of treated wastewater showed that organic matter had been significantly removed. Source

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