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Effect of gamma ray irradiation on chemical composition, antioxidant, antimicrobial, and insecticidal activities of Thymus pallescens essential oil

Alloun K., Benchabane O., Hazzit M., Mouhouche F., Baaliouamer A., Chikhoune A., Benchabane A.

Acta Chromatographica

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2019

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Vol. 31, no. 1

57--62

EN

The essential oils isolated by hydrodistillation from Thymus pallescens de Noé dried leaves exposed to γ-irradiation at dose levels of 0, 5, 10, 20, and 30 kGy were analyzed by gas chromatography–flame ionization detector (GC–FID) and GC–mass spectrometry (MS) and tested for their antioxidant, antimicrobial, and insecticidal activities. No qualitative change was observed in the chemical composition. Carvacrol (81.8–85.7%) was the most prominent component. Gamma-irradiation at 20 kGy affects quantitatively some components. Antioxidant activity was evaluated by four different test systems, namely, inhibition of lipid peroxidation (thiobarbituric acid reactive substance, TBARS), ferric reducing power, and scavenging of radicals DPPH• and ABTS•+. In all systems, irradiated oils at 20 and/or 30 kGy showed the most antioxidant efficiency. Overall, the antimicrobial activity conducted against seven microorganisms revealed no significant changes according to the radiation dose. Fumigation bioassays and contact method against confused flour beetle Tribolium confusum revealed that the oil irradiated at 20 kGy had highest insecticidal activity. The results showed that gamma-irradiation of T. pallescens could be not only beneficial safe decontamination perspective but also as an improvement factor of some of its properties.

2

Effect of activated carbon on methomyl poisoning by urine metabolomics base on gas chromatography–mass spectrometry

Li L., Hu L., Chen B., Dong Y., Lin Z., Wang Z., Wen C., Wang X., Wang S.

Acta Chromatographica

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2018

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Vol. 30, no. 1

21--25

EN

In this study, we developed a urine metabolomic method by gas chromatography–mass spectrometry (GC–MS) combination with biomedical results to evaluate the effect of activated carbon on methomyl poisoning rats. The rats were divided into four groups, methomyl group, two activated carbon treatment group, and control group. According to the biochemical results, it indicated that activated carbon treated rats could cause liver and kidney function changes. According to the urine metabolomics results, activated carbon treatment group (10 min) and activated carbon treatment group (30 min) could be distinguished from methomyl group, and activated carbon treatment group (10 min) could be separated from activated carbon treatment group (30 min) rats, which indicated that the treatment of rats by activated carbon in different time had a different effect. The results indicate that metabolomic method by GC–MS may be useful to elucidate activated carbon treated on methomyl poisoning rats.

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Dispersive liquid–liquid microextraction for the simultaneous determination of parent and nitrated polycyclic aromatic hydrocarbons in water samples

Borges B., Melo A., Ferreira I., Mansilha C.

Acta Chromatographica

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2018

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Vol. 30, no. 2

119--126

EN

A new method for simultaneous extraction and quantification of 6 nitrated polycyclic aromatic hydrocarbons (nitro-PAHs) and 16 parent polycyclic aromatic hydrocarbons (PAHs) in water matrices was optimized and validated. The extraction procedure was based on dispersive liquid-liquid microextraction technique, followed by gas chromatography-mass detection. The optimum conditions of extraction (volume of the extraction solvent, dispersive solvents and amount of salt) were selected using central composite design. The best results were found by using 200 μL of acetonitrile as dispersive solvent, 60 μL of chloroform as extraction solvent, and 10% (w/v) NaCl. Excellent linearity was observed in the range of 10–150 ng L−1 with correlation coefficients (r2) ranging between 0.9996 and 0.9999 for nitro-PAHs and in the range of 5–150 ng L−1 with r2 ranging from 0.9998 to 1.000 for PAHs. The limits of detection for the nitro-PAHs studied ranged from 0.82 to 3.37 ng L−1, whereas for PAHs ranged from 0.62 to 3.48 ng L−1. The intra- and inter-day precisions for nitro-PAHs were in the range of 0.45 to 19.54% and 0.43 to 19.62%, respectively, and for PAHs ranged between 0.45 to 17.42% and 0.38 to 18.97%, respectively. The proposed method was successfully applied in analyses of groundwater, sea, rain water and river water, being appropriate for routine analyses.

4

Development of simple analytical methods of polychlorinated biphenyls in human serum by gas chromatography negative ion chemical ionization quadrupole mass spectrometry

Eguchi A., Enomoto T., Suzuki N., Okuno M., Mori C.

Acta Chromatographica

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2017

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Vol. 29, no. 4

503--506

EN

In this study, we developed a highly sensitive, robust method for determining 12 congeners of two to ten chlorinated polychlorinated biphenyls (PCBs) in serum samples using gas chromatography (GC)–mass spectrometry (MS) operating in selected ion monitoring mode (SIM: m/z 35) with negative ion chemical ionization (NICI), and the results were compared with those from GC coupled with high-resolution MS (HRMS) with electron impact (EI). The recovery rates of the surrogate PCB congeners were 97.2%–112% (coefficient of variation: 5.3%–8.5%), and the method detection limits for PCBs in each matrix obtained by GC–NICI–quadrupole mass spectrometry (qMS) were 1.9–20 pg g−1 wet wt. The analytical values of the target compounds in the samples analyzed by GC–NICI–qMS and GC–EI–HRMS were comparable (Passing–Bablok regression: R = 0.888–0.967), and the analytical values obtained via GC–NICI–qMS were almost comparable with those of the certified serum samples from National Institute of Standards and Technology (NIST: SRM1957), indicating that GC–NICI–qMS is suitable for the analysis of tetra- to hepta-chlorinated PCBs in serum samples.