Refaat, A. M., Momen, F. M. and Amer, S. A. A. (2002): Acaricidal activity of sweet basil and French lavender essential oils against two species of mites of the family tetranychidae (Acari: Tetranychidae). Acta Phytopathologica et Entomologica Hungarica
The lavender genus ( Lavandula ) belongs to the mint family ( Lamiaceae Lindl.). It comprises 39 species, numerous hybrids, and approximately 400 registered varieties [ 1 ]. Lavandula is native to the
Authors:Mamdouh R. Rezk, Abd El-Aziz B. Abd El-Aleem, Shaban M. Khalile, and Omneya K. El-Naggar
Lavender and rosemary are shrubs that have many medicinal uses. Like any other shrubs, they are susceptible to pest infection which needs pesticides treatment. Residues of pesticides in lavender and rosemary leaves may be hazardous to human health. The main objective of this study was to develop accurate and sensitive methods for the determination of residues of pesticides, namely, diazinon and chlorpyrifos, in lavender and rosemary leaves. Thin-layer chromatography (TLC) fractionation was applied to separate the desired pesticides to be analyzed and to determine the rate of the disappearance of these pesticides from lavender and rosemary leaves. Diazinon and chlorpyrifos were separated from extracts of leaves using silica gel 60 F254 plates. The mobile phase was formed of petroleum ether–ethanol–glacial acetic acid (9.5:0.5:0.1, v/v) and (9.0:1.0:0.1, v/v) as the developing systems for diazinon and chlorpyrifos, respectively, followed by densitometric measurement at 254 nm for both pesticides. The methods were validated over a range of 0.01–l.6 μg band−1 for diazinon and 0.04–2.0 μg band−1 for chlorpyrifos. The detection limits of diazinon and chlorpyrifos were 0.003 and 0.012 μg band−1, respectively. The safe harvest interval (pre-harvest interval; PHI), time in days between the last pesticide application to the crop and the time it can be safely harvested, was suggested to be 21 and 24 days for diazinon and chlorpyrifos, respectively. The developed TLC methods were used for sample cleanup and estimation of the studied pesticides residues in leaves extracts, in addition to the determination of the pre-harvest interval.
The direct toxicity of four essential oils, Majorana hortensis Moench, Rosmarinus officinalis L., Mentha piperita L. and Lavandula officinalis Chaix, to adult females of the predacious mite Amblyseius swirskii Athias-Henriot were tested. Peppermint oil was the most toxic to females A. swiriskii while the French lavender oil was the least toxic to the predator. All essential oils, at the two concentrations used, decreased the food consumption rate as well as egg laying. All four materials tested, at concentration 0.25% were considered to be safe for the predator since no mortalities had been recorded.
Authors:C. Cordella, J.-P. Faucon, D. Cabrol-Bass, and N. Sbirrazzuoli
The thermal behaviour of authentic honeys and sugar syrups (industrial and homemade) was investigated by DSC. To confirm the first previous results concerning the effect of adulteration on the thermal behaviour of authentic honeys, 30 honey samples (Robinia, Lavender, Chestnut and Fir) were analyzed by DSC and their Tg were measured following a suited experimental protocol. The results indicated that this parameter was useful to characterize and to distinguish significantly these varieties between them. Applied to honey samples artificially adulterated with different industrial syrups, DSC showed a detection level of 5–10% depending on the type of syrup. An endothermic phenomenon occurring between 40–90°C during the heating was studied by TMDSC and a new thermal transition similar to a glass-transition was highlighted.
Authors:A. Hazra, K. Alexander, D. Dollimore, and A. Riga
The present study was aimed at determining the kinetics of evaporation and establishing vapor pressure curves for both single and multi-component systems by thermogravimetry (TG) and differential scanning calorimetry (DSC). Essential oils (e.g. lavender oil, orange oil, clove oil and eucalyptus oil, etc.) are typically multi-component systems consisting of various volatile pure components (e.g. linalyl acetate, limonene, cinnamaldehyde, etc.) which resemble single component systems. In this study linalyl acetate was taken as the calibration compound for TG. The vapor pressure curves for the pure substances were plotted using TG and vapor pressure plots for clove oil and eucalyptus oil were constructed using DSC. The thermodynamic and kinetic parameters of the pure compounds were compared to that of the multi-component systems to quantitatively and qualitatively measure the influence of different compounds on each other. The k-value from the vapor pressure data for linalyl acetate was calculated as 112006 Pa kg0.5mol0.5s-1 m-2 K-0.5. The vapor pressure values were used to determine the Antoine constants using the SPSS 10.0 software.