Vol 73, No 10 (2018)

This review surveys chiral chromatographic phases, their properties and preparation methods, and applicability to gas chromatography. New chiral chromatographic phases based on cyclodextrins, ionic liquids, liquid crystals, cyclofructans, etc., are considered. Chiral stationary phases obtained with the use of nanomaterials (structured polymers, including those with molecular traps and molecular imprints, organometallic structures with different types of chirality, and chiral stationary phases based on supramolecular self-assembling structures with induced chirality) are considered separately. It is shown that the chiral phases based on nanomaterials exhibit high enantioselectivity for difficult-to-separate racemates.

Melatonin (N-acetyl-methoxytryptamine) is secreted from a part of the brain called suprachiasmatic nuclei. The biological clock of the body or the circadian rhythm is regulated through the secretion of hormones such as melatonin and cortisol. The dispersive liquid–liquid microextraction (DLLME) was optimized for the determination of human salivary melatonin. Different variables including the nature of extracting and dispersing solvent, their volumes, sample pH, ionic strength, extraction and centrifugation times were screened using One Factor At a Time design and then, the significant variables were selected as optimum values. Accuracy and precision of the optimized method were evaluated at concentrations of 50, 100, 250 pg/mL by achieving CV% for day-to-day and within-day reproducibility. Considering the appropriate results of the study, DLLME procedure can be used for the determination of melatonin hormone in saliva samples.

Phosphorus-doped carbon nanocages are prepared from the mixture of triphenylphosphine and benzene through a chemical vapor deposition method. The as-prepared phosphorus doped sample displays a three dimensional nanosized hollow structure with high specific surface area. Based on these unique properties, phosphorus-doped carbon nanocages have been developed to fabricate an electrochemical sensor. The cyclic voltammetry experimental results indicate that the sensor possesses an excellent catalytic capacity. Compared with carbon nanotubes, the prepared sensor shows a higher sensitivity for dopamine and uric acid. The sensor also shows good selectivity for these analytes. With the acceptable reproducibility and stability, the sensor is applied for real samples with satisfactory results. The simple and efficient sensor in the present work implies that the phosphorus-doped carbon nanocages can be further used for other compounds determination.

A procedure is developed for the simultaneous highly sensitive determination of eight chlorophenols in sea water based on a combination of isotope dilution, solid-phase extraction on an octadecyl adsorbent, acetylation, and determination by gas chromatography–tandem mass spectrometry with electron ionization. The attained limits of detection for the analytes are in the range 0.06−0.26 ng/L, which is 2−3 orders of magnitude lower than the standards established for the maximum permissible concentration. The duration of analysis is 15 min. The application of a deuterated internal standard ensures the high accuracy and reproducibility of the results obtained. The developed procedure was successfully used for the analysis of real water samples from the Barents Sea; the found total chlorophenol concentration in them was 15–24 ng/L. The main pollutant of the studied sea water samples is 2,4-dichlorophenol, which comprised about 30% of the total concentration of chlorophenols.

Direct headspace gas chromatographic analysis with flame ionization and mass spectrometric detection was used to identify and quantify volatile organic compounds (VOCs) in the headspace of the medicinal plant material of Common Tansy (Tanacetum vulgare L.) and preparations of its oil and tablet dry extract. All the main components of the headspace of medicinal plant raw material of Tansy are present in the headspace of phytopreparations. The retention indices of VOCs \(\left( {I_{i}^{T}} \right)\) were determined for the linear programmed temperature of a column with a 5% diphenyl–95% dimethylpolysiloxane stationary phase and the relative peak areas (A_rl,i) in the chromatogram are determined. It is shown that the specific chromatographic profiles of VOCs, which represent the set of values of \(I_{i}^{T}\) and A_rl,i, for Tansy samples from different regions of Russia are similar.

The physical and chemical characteristics of ecstasy have been extensively investigated for many years, but establishing links between the seizures, determining their origin, and monitoring the abuse traffic of this drug through analytical and statistical methods have only recently become a research topic. In this study, the ecstasy samples seized by the Turkish National Police were analyzed to obtain their chemical characteristics. In the chemical profiling, 17 elements and main organic constituents such as MDMA and amphetamine were identified in 18 ecstasy samples. The chemical profiles of the seizures were also statistically assessed using hierarchical cluster, principal component and correlation analyses. The Ba, Cu, Co, Rb and Pb elements indicated that the seizures came from the same network, and therefore, these elements can be used to obtain the origin of the seizures and monitor the abuse traffic of ecstasy.