Chemical Composition and Antioxidant Activity of Algerian Juniperus Phoenicea Essential Oil

Berries and branches essential oil of Juniperus phoenicea were obtained by electromagnetic induction heating assisted extraction and by hydrodistillation with a yield varied from (1.2 ± 0.3 to 2.4 ± 0.7%) and from (0.6 ± 0.1% to 1.1 ± 0.1%), respectively. forty eight compounds were identified representing (97.2 – 99.7%) of the oil. α-Pinene (40.3 – 67.8%) and δ-3-carene (13.5 – 26.8%) were the main compounds in berries and branches essential oils. Antioxidant activity was evaluated by three means: inhibition of 2, 2-diphenyl-1-picryl hydrazyl (DPPH) free radical, reducing power and β-Carotene/linoleic acid bleaching. The antioxidant activity of essential oils showed IC₅₀ ranging from 67.6 ± 1.02 µg/mL to 131.5 ± 0.8 µg/mL for berries and from 98 ± 1.25 µg/mL to 166.8 ± 0.29 µg/mL for the branches. Berries oil show more potent antioxidant activity compared to branches. This result is supported by the three methods investigated in this work.

Optimization of Algerian Thymus fontanesii Boiss. & Reut Essential Oil Extraction by Electromagnetic Induction Heating

The present study deals with the determination of optimal values of operating parameters such as the temperature of heating, the mass of the plant material and the volume of water leading to the best yield of electromagnetic induction (EMI) heating extraction of Algerian Thymus fontanesii essential oil. After an appropriate choice of the three critical variables, eight experiments leaded to a mathematical model as a first-degree polynomial presenting the response function (yield) in the relation to the operating parameters. From the retained model, we were able to calculate the average response, the different effects and their interactions. The maximum of essential oil recovery percentage relative to the initial mass of plant material was 1.69%, and was obtained at (140 ℃, 250 g and 4.5 L). The chemical composition of the Algerian T. fontanesii essential oil under the obtained optimal conditions (140 ℃, 250 g and 4.5 L), determined by GC/MS and GC/FID, reveled of the presence of major components such as: carvacrol (70.6 ± 0.1%), followed by p-cymene (8.2 ± 0.2%).

Determination of Trace Inorganic Mercury in Mineral Water by Flow Injection On-line Sorption Preconcentration-Cold Vapor Atomic Fluorescence Spectrometry / 分析化学

Flow injection on-line sorption preconcentration and separation in a knotted reactor (KR) was coupled to cold vapor atomic fluorescence spectrometry for the determination of trace mercury in mineral water. Mercury was preconcentrated by on-line formation of mercury diethyldithiocarbamate complex (Hg-DDTC) and absorption of the resulting neutral complex on the inner walls of a knotted reactor. A 20%(V/V) HNO3 solution heated by electromagnetic induction heating technique was used as eluent to remove the absorbed Hg-DDTC from the KR, and then the vapor mercury generated by mixing the resulting solution and KBH4 was determined on-line by cold vapor atomic fluorescence spectrometry. The 20% HNO3 was employed as both the efficient eluent and the required acidic medium for subsequent mercury vapor generation in our work. Using 20% HNO3 instead of conventional organic solvent as eluent, the proposed method is simple, easy operational and environmentally friendly. Under the optimal experimental conditions, the sample throughput was approximatively 30/h with an enhancement factor of 35. The detection limit of mercury was 2.0 ng/L. The precision(RSD, n=11) was 2.2% at the 0.1 μg/L Hg2+ level.