Joint quantification of PAH and oxy-PAH from standard reference materials (urban dust and diesel particulate matter) and diesel soot surrogate by GC-MS

The combustion of fossil fuels produces pollutants such as soot, which consists of carbonaceous particles whose emission is regulated by environmental laws. Soot is mainly formed from polycyclic aromatic hydrocarbons (PAH), through different reaction ways and, once formed, it can adsorb PAH on its surface. These compounds have an environmental importance due to their carcinogenic and mutagenic potential. In the last years, the oxygenated derivatives of PAH (oxy-PAH) have also been considered as dangerous since they have been found to be mutagenic for bacterial and human cells. Therefore, the purpose of this work was to quantify simultaneously selected PAH and oxy-PAH from different samples of soot. The quantification method involves Soxhlet extraction and subsequent concentration by rotary evaporation that allows to recover the analysed compounds from soot samples. The PAH and oxy-PAH were identified and quantified, by a single injection, using a gas chromatograph-mass spectrometer (GC-MS). The method showed a good repeatability using a diesel soot surrogate test sample, Printex-U. The validation process showed that most of the compounds are recovered between the values established for the Standard Reference Materials analysed, 1650b and 1649b. The values of the mass fraction of the oxy-PAH obtained in this work showed, in general, a good match with those indicated in other studies

Application of untargeted metabolomics to determine volatile compounds from the Spanish plant Arctostaphylos uva-ursi used as tea

One-hundred and seven different volatile compounds were identified in the samples of Arctostaphylos uva-ursi collected from nine locations in Spain. This plant is commonly brewed and used as tea. Volatile compounds profile was detected using solid-phase microextraction gas chromatography-mass spectrometry. The most interesting compounds detected from an antioxidant capacity point of view were esters, phenols, and aromatics compounds. All samples were discriminated by principal component analysis. The insolation and altitude of harvest areas, and latent structures were considered for interpretation of results. Discriminant analysis was applied to control the type and concentration of metabolites and determine the best plant antioxidant profiles of volatile compounds from plant origin. Moreover, a heatmap displayed correlations between detected compounds. The discriminant analysis led to 20 quality markers being identified for the analysed plants. The strongest antioxidant capacity was obtained in the samples from Pina de Montalgrao and Loarre (collected in September) for ORAC (33.11 ± 0.61 g Trolox/g sample) and DPPH (IC50 = 711 ± 12 µg/g) methods, respectively. The plant with the highest total phenolic content was Loarre collected in September (171.9 ± 19.4 mg GAE/g DW) and November (177.1 ± 11.0 mg GAE/g DW)

A sulphuric acid-impregnated silica gel clean-up procedure for the determination of n-alkanes migration from paraffin based paper packaging into cheddar cheese

A procedure for the determination of n -alkanes migration from paraffin paper packaging into fatty foods has been fully developed. First, the lipid fraction of the cheddar cheese is extracted with a mixture of diethyl ether/ n -hexane (1:1). Then, a sulphuric acid-impregnated silica gel (SAISG) clean-up procedure is performed and the final extract is analysed by gas-chromatography (GC) with flame ionisation detector (FID). The procedure has been validated in terms of limits of detection and quantification, linear range, recovery, precision and robustness. The method has been used in the evaluation of the n -alkane migra- tion from paraffin coated paper into cheddar cheese. Results after 10 days of migration test showed the typical n -alkanes (C 19 –C 37 ) profile of migration with a maximum (21.1 ± 10.8 l gg 1 )in n -pentacosane (C 25 )

Development of a quantitative colour-based software method to evaluate the effectiveness of active antioxidant packaging on fresh sliced mushrooms

A software-based procedure consisting of colour measurement of mushrooms was developed for assessing the effectiveness of a new antioxidant active packaging. As active agents, sodium metabisulphite combined with citric acid, green tea extract combined with α-tocopherol and purple carrot extract were evaluated. After obtaining the image of mushrooms with a conventional flatbed scanner, a MATLAB code was specially designed to obtain and compare histograms. Then, data were processed using principal component analysis (66% of the accumulated variance explained) and a successful classification of samples according to their age and antioxidant system was obtained. The developed procedure greatly exceeded the discrimination capabilities of other commonly used methods such as CIE L*a*b* (which was unable to find any significant difference between blank and antioxidant-treated mushrooms; L*blank = 70 ± 3; L*metabisulphite = 75 ± 5; L*green tea = 75 ± 5; L*carrot = 69 ± 5) and visual panel (where only sodium metabisulphite sample was perceived to be significantly different from the rest of the samples, with 27 positive votes out of 50). The developed method classified correctly up to 90% of blank samples according to their age. Besides, 100% and 70% of the mushrooms treated with sodium metabisulphite and green tea, respectively, were found to be fresher than their corresponding blanks. Among samples with sodium metabisulphite, 33% behaved as one-day blank samples, and 67% acted as 4-day blank samples, while among samples with green tea, 10% were found in the 1-day group, and 60% were found in the 4-day group. In contrast, purple carrot proved to be inefficient as an antioxidant. Thus, the difference between blank mushroom samples and those treated with antioxidants was objectively measured

Determination of volatile organic compounds in recycled polyethylene terephthalate and high-density polyethylene by headspace solid phase microextraction gas chromatography mass spectrometry to evaluate the efficiency of recycling processes

A method for the determination of volatile organic compounds (VOCs) in recycled polyethylene terephthalate and high-density polyethylene using headspace sampling by solid-phase microextraction and gas chromatography coupled to mass spectrometry detection is presented. This method was used to evaluate the efficiency of cleaning processes for VOC removal from recycled PET. In addition, the method was also employed to evaluate the level of VOC contamination in multilayer packaging material containing recycled HDPE material. The optimisation of the extraction procedure for volatile compounds was performed and the best extraction conditions were found using a 75 μm carboxen-polydimethylsiloxane (CAR-PDMS) fibre for 20 min at 60 °C. The validation parameters for the established method were linear range, linearity, sensitivity, precision (repeatability), accuracy (recovery) and detection and quantification limits. The results indicated that the method could easily be used in quality control for the production of recycled PET and HDPE12181013191330CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQCOORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPESSem informaçãoSem informaçã

Determination of volatile organic compounds in recycled polyethylene terephthalate and high-density polyethylene by headspace solid phase microextraction gas chromatography mass spectrometry to evaluate the efficiency of recycling processes

A method for the determination of volatile organic compounds (VOCs) in recycled polyethylene terephthalate and high-density polyethylene using headspace sampling by solid-phase microextraction and gas chromatography coupled to mass spectrometry detection is presented. This method was used to evaluate the efficiency of cleaning processes for VOC removal from recycled PET. In addition, the method was also employed to evaluate the level of VOC contamination in multilayer packaging material containing recycled HDPE material. The optimisation of the extraction procedure for volatile compounds was performed and the best extraction conditions were found using a 75 mu m carboxen-polydimethylsiloxane (CAR-PDMS) fibre for 20 min at 60 degrees C. The validation parameters for the established method were linear range, linearity, sensitivity, precision (repeatability), accuracy (recovery) and detection and quantification limits. The results indicated that the method could easily be used in quality control for the production of recycled PET and HDPE. (C) 2011 Elsevier B.V. All rights reserved.CAPESCNPq, BrazilGobierno de Aragon, through the GUIA group of Grupo Consolidado de Investigacion T-10-Universidad de Zaragoz

Analysis of Bioactive Aroma Compounds in Essential Oils from Algerian Plants: Implications for Potential Antioxidant Applications

In samples of Artemisia campestris (AC), Artemisia herba-alba (AHA) and Salvia jordanii (SJ) essential oils, up to 200 distinct volatile compounds were identified. Using headspace solid-phase microextraction combined with gas chromatography–olfactometry–mass spectrometry (HS-SPME-GC-O-MS), different panelists detected 52 of these compounds. This study offers the most detailed analysis of bioactive compound profiles conducted so far. The most abundant compounds identified were curcumene, making up 12.96% of AC, and camphor, constituting 21.67% of AHA and 19.15% of SJ. The compounds with the highest odor activity value (OAV) were (E,Z)-2,4-nonadienal (geranium, pungent), 3-nonenal (cucumber) and 2-undecenal (sweet) in AC, AHA and SJ, respectively. AHA essential oil showed significant antioxidant activity (IC50 = 41.73 ± 4.14 mg/g) and hydroxyl radical generation (hydroxylation percentage = 29.62 ± 3.14), as assessed by the diphenylpicrylhydrazyl (DPPH) method. In terms of oxygen radical absorbance capacity (ORAC), the strongest antioxidant activity was obtained for SJ essential oil (antioxidant activity of the essential oils, AOX = 337.49 ± 9.87)