Volatile Components in Cordierite and Coexisting Tourmaline and Quartz from Pegmatites of the Kuhilal Deposit (Pamir, Tajikistan)

—The compositions of volatile components in cordierite, tourmaline, and quartz from pegmatites of the Kuhilal deposit were studied by pyrolysis-free gas chromatography–mass spectrometry (GC–MS), IR and Raman spectroscopy, and microthermometry, and their comparative analysis was performed. Capillary GC–MS was applied to determine the component composition and relative contents (rel.%) of volatiles from different zones of crystals and fractions of cordierite. It has been established that water and carbon dioxide prevail among them. Among hydrocarbons, aliphatic, cyclic, and oxygenated ones are predominant. Heterocyclic, nitrogenated, and sulfonated compounds have also been found. In tourmaline and quartz, volatile components are present in gas–liquid inclusions; in cordierites, they are localized both in structural cavities and in nonstructural positions.

A novel column modification approach for capillary gas chromatography: combination with a triptycene-based stationary phase achieves high separation performance and inertness

Integration of the novel column modification approach with a triptycene-based stationary phase achieves high-resolution performance and inertness towards acids/bases and isomers for capillary GC analysis.

Improved method for determination of waxes in olive oils: reduction of silica and use of a less hazardous solvent

The evaluation of the content of waxes is request both by IOC Trade Standard and by Regulation (EEC) 2568/91 and its further amendments. The official method uses 15 g of silicic acid and elutes several fractions by using huge volumes of dangerous solvent (n-hexane). The developed method uses 1 g of silicic acid with a different particle size and less than 20 mL of solvent mixture, substituting n-hexane with less toxic isooctane. Briefly, after spiking with a suitable internal standard, oil sample is fractionated by SPE (Solid Phase Extraction) cartridge with 1 g of silica, waxes are eluted with 14 mL of isooctane/ethyl ether 99/1 (6 mL discarded and 8 mL collected), then, after elution sample is reconstitute in 200 μL of n-heptane and analysed by capillary GC. Data of “In home” validation, (repeatability, accuracy and recovery) and relative chromatograms are reported in this paper.

Determination of Residues of Diazinon and Chlorpyrifos in Lavender and Rosemary Leaves by Gas Chromatography

A sensitive gas chromatographic (GC) GC method has been developed for the determination of diazinon and chlorpyrifos residues in lavender and rosemary leaves. The developed method consists of blending weighed samples of chopped leaves with sodium sulfate as the dehydrating agent, extraction with ethyl acetate, filtration, evaporation with a rotary evaporator, and, finally, capillary GC determination of the pesticides. The recoveries of the method were greater than 90%, and the LOQ was less than 0.1 µg/mL. The method was applied to determine the rate of disappearance of diazinon and chlorpyrifos from lavender and rosemary leaves pretreated with the studied pesticides. The half-life values (t1/2) of diazinon were found to be 5.93 and 6.35 days for lavender and rosemary leaves, respectively, whereas the t1/2 values of chlorpyrifos were calculated to be 7.86 and 9.52 days for lavender and rosemary leaves, respectively. The safe harvest interval (preharvest interval; PHI) was suggested to be after 21 and 24 days for diazinon and chlorpyrifos, respectively. The PHI refers to the amount of time that must lapse (in days) after a pesticide application before a crop can be cut.

Experimental Paper. The effect of different development stages on the quantity and quality of the essential oil of Citrus aurantifolia (Christm.) Swingle in Iran

Summary Introduction: The Mexican lime tree with the scientific name of Citrus aurantifolia (Christm.) Swingle have great economic value because of its essential oil with a unique flavour. Objective: The essential oils from the peel of C. aurantifolia were collected during three development periods. Methods: The essential oil was analyzed by capillary GC and GC-MS. Results: The essential oil yields (v/w%) were 1.54%, 0.88% and 1.23%, respectively. The highest oil yield was obtained at stage I (1.54% v/w). The analysis of the essential oil indicated that limonene, β-pinene, geranial, neral and γ-terpinene were the main compounds of all samples. At the first stage, the highest percentages belonged to limonene (39.38%), geranial (14.32%) and neral (11.01%). On the other hand, the highest percentages of β-pinene and γ-terpinene (24.25% and 8.92%, respectively) were found at the final stage. Conclusion: Therefore, it is concluded that the harvest time has a considerable effect on the content and amount of lime fruit essential oil.