A plasma surface treatment of biaxially oriented polypropylene (BOPP) film was carried out with dielectric barrier glow discharge (DBGD) in Ar/air. The paper studied the effects of the ratios of Ar/air plasma on the BOPP surface modification. The results indicated that the efficiency of the plasma surface modification was improved with increasing treatment time and power density with DBGD in Ar/air. The water contact angle increased first and then decreased with the increase of the Ar/air mixture rate. The DBGD gives a better surface modification than filament discharge. The ageing behavior was influenced by the mixture rate of Ar/air, but the water contact angle of the treated sample was always less than that of un-treated sample.
A method for the fast determination of the components in a complex sample by using gas chromatography with mass spectrometry was developed and used for the quantitative analysis of phthalic acid esters in environmental water. In the method, the adaptively corrected mass spectra were used to compensate for the differences between the library spectra and the measured ones in the experiment. The correction was obtained by the iterative transformation of the library spectra using iterative target transformation factor analysis, and the resolution was performed by non-negative immune algorithm using the corrected spectra. Rapid analysis of 16 phthalic acid esters in water samples was achieved using fast elution gas chromatography with mass spectrometry measurements. The results show that the mass spectra and chromatographic profiles of the phthalic acid esters can be obtained from the overlapping signal of 13 min elution, and accurate quantitative analysis can be obtained. The recoveries of the phthalic acid esters obtained by standard addition are between 90.3 and 107.4%, and the relative standard deviations obtained in repeated measurements are less than 9%.
Chemometric methods have been proved to be a powerful tool for resolution of overlapping signals. Immune algorithm (IA) is one of the chemometric approaches for analyzing multi-component GC-MS signals. The method extracts the information of the components by iteratively eliminating standard information (chromatogram or mass spectrum) from overlapping GC-MS signals. In the primary IA, however, the standard signal of each component possibly contained in the mixture must be provided by measuring the standard or by theoretical simulation. When there is difference between the measured signals of the standards and the mixture, distortion and negative values will appear in the resolved chromatograms. In order to conquer the problem, an algorithm based on an alternative iteration of least squares fitting and IA was proposed in this work. In the method, the measurement of GC-MS was achieved with a very fast temperature program to make the analytes to elute within a short retention time period, and then the chromatographic and mass spectral information of the components in the overlapping signal is calculated with the proposed algorithm. In the calculation, the algorithm takes random mass spectra of the components as the starting input, and then the information of each component is obtained with an alternating iterative process. In the iteration, the mass spectra are calculated by using the least squares fitting and the chromatographic profiles are resolved by IA. Furthermore, the non-negative and unimodality constraints are adopted in the calculation for improving the resolved results. The iteration stops when the remaining signal does not change. The feasibility of the method was validated by using a simulated GC-MS data matrix of a three-component mixture, and the practicability of the method was proved by resolving the GC-MS data of the 40-pesticide mixture. The results show that both the mass spectra and the chromatographic information of the components were extracted from the overlapping signals, and the pesticide mixture was analyzed within 10 min elution with the help of the proposed method.
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