Use of Local Lagrange Interpolation for calculation of retention indices in linear temperature-programmed gas chromatrography

Summary The influence of the isothermal temperature, program rate, initial temperature and flow rate on retention indices was studied. The methods of Kováts, Van Den Dool and Local Lagrange Interpolation are compared. Ten experimental measurements were carried out on a capillary column coated with OV-101 stationary phase.     

Chemical composition and physicochemical characteristics of fixed oils from algerian <Emphasis Type="Italic">Nigella sativa</Emphasis> seeds

The fatty acids, sterols, and polyphenols from the fixed oils of Nigella sativa seeds originating from four locations were determined. The seeds contained respectively 30.63–34.27% and 25.66–32.77% of fixed oils using hexane and isopropyl alcohol in solvent extraction. Linoleic, oleic, and palmitic acids formed the main proportion using the two solvents, respectively: hexane 54.47–61.28%, isopropanol 56.98–67.30%; hexane 19.62–22.94%, isopropanol 18.85–21.96%, and hexane 11.17–13.60%, isopropanol 9.20–14.18%. Other minor unsaturated fatty acids were identified. Eight phytosterols were isolated and identified in the fixed oils by GC and GC/MS analysis, wherein β-sitosterol was the dominating compound that inhibits the absorption of dietary cholesterol, followed by stigmasterol, campesterol, and Δ⁵-avenasterol.     

GC and GC/MS analyses of the Algerian Lantana camara leaf essential oil: Effect against Sitophilus granarius adults

The bioactivity of the essential oil extracted by hydrodistillation from Lantana camara leaves was assessed under laboratory conditions. The composition of L. camara essential oil included large amounts of sesquiterpene, mainly β-caryophyllene (35.70%) and caryophyllene oxide (10.04%). The tested essential oil showed good fumigant activity within 1 week of exposure for all tested doses. Moreover, remanence study confirmed that the oil was efficient during 2 weeks.     

On‐Line Radical Scavenging Detection and Characterization of Antioxidants from Artemisia herba‐alba

Four caffeoylquinic acid (CQA) derivatives, 5‐O‐caffeoylquinic acid ( 1 ), 3,5‐di‐O‐caffeoylquinic acid ( 3 ), 4,5‐di‐O‐caffeoylquinic acid ( 4 ), and 3,4,5‐tri‐O‐caffeoylquinic acid ( 5 ), have been isolated from Artemisia herba‐alba growing wild in Algeria, using the on‐line HPLC? DAD? DPPH radical‐scavenging detection technique as guidance. In the course of the purification work, the non‐frequent (E)‐2‐(β‐D ‐glucopyranosyloxy)‐4‐methoxycinnamic acid ( 2 ) has also been isolated. The CQAs showed fair‐to‐good antioxidant activities determined by the DPPH^. scavenging assay. The structures of the five isolated compounds were determined by spectroscopic methods. The on‐line HPLC? DAD? DPPH technique allowed for a rapid pinpointing of antioxidants in the studied plant, accomplishing the facile guided isolation of the target molecules. Algerian A. herba‐alba could be an interesting source of natural antioxidants that deserve further work.     

Kinetic Study of Microwave Extraction of Essential Oil of Nigella sativa L. Seeds

The Nigella sativa L. is widely cultivated in the Algerian Sahara and primarily used for its health benefits. Extraction experiments were carried out by a microwave energy, performed at atmospheric pressure with a small quantity of water for 10 min. This method enabled a best yield (0.54–0.57%) and a high amount of the volatile fraction with a shorter extraction time and a reduction of energy consumption. The kinetic study of essential oils extraction was quantitatively studied. Thus, the qualitative and quantitative composition of the essential oils extracted for 10 min and in different periods was examined by capillary gas chromatography and by gas chromatography-mass spectrometry. The percentage of the main constituents such as p-cymene, thymoquinone, α-thujene, 4-terpineol and carvacrol was reported. The family classes present a significant variation according to the extraction time. Kinetic and extraction rate profile of microwave process (yield) showed that it is possible to reduce the extraction time.