Nearing 130 years since their introduction, liquid crystals (LCs) have found diverse applications in different fields of science, including chemical analysis. This review encompasses the history of ...LCs, reviews various types of them, and presents their current applications in analytical chemistry. Since most applications of LCs in analytical chemistry are for the fabrication of biosensors, these applications are discussed first. The high sensitivity of LCs to changes in their environment makes them ideal for such sensors. Using them, analyte concentrations as low as 1 pM have been detected. Another major application of LCs is in gas chromatography (GC) as stationary phases, which is described in the second part of this review. Using LCs in GC leads to better separations, higher sensitivity, and improved selectivity. Such phases provide higher stability in elevated temperatures and increased column life times. Finally, applications of LCs in electro-analytical chemistry will be described briefly.
The Indian meal moth, Plodia interpunctella (Hübner) (Lepidoptera: Pyralidae) is an important insect pest on a wide range of stored food diets. This study employed gas-liquid chromatography to ...investigate the influence of different diets (pistachio, raisins, and walnuts) on the composition of phospholipids and triglycerides in fifth instar larvae of P. interpunctella. The fatty acid profiles of the larvae revealed seven essential fatty acids including myristic, palmitic, palmitoleic, stearic, oleic, linoleic, and linolenic acids. The fatty acid composition of larvae-extracted phospholipids and triglycerides also varied according to the diet type. In terms of phospholipids, the highest concentration of myristic acid was observed in larvae fed walnut. Raisins exhibited the highest levels of palmitoleic and oleic acid, while pistachio demonstrated the highest concentration of linoleic acid. However, no significant differences were observed among the treatments concerning palmitic acid, stearic acid, and linolenic acid. Regarding triglycerides, no significant differences were found among the treatments in terms of myrisitc acid and oleic acid. However, the raisins treatment displayed the highest amount of palmitoleic acid, while both pistachio and walnut treatments exhibited the highest levels of linoleic acid. Additionally, the concentration of linolenic acid in larvae fed walnut was higher than other test diets. These findings provide valuable insights into the fatty acid composition of P. interpunctella fed different diets. Such knowledge can be utilized in developing pest management strategies, as the manipulation of fatty acid profiles in insects’ diet could potentially impact their growth, development, and fitness.
•Plodia interpunctella is a devastating pest of a wide range of stored diets.•Fatty acid profiles of 5th instar larvae revealed seven essential fatty acids.•Fatty acid compositions of P. interpunctella varied according to the diet type.•The highest concentration of myristic acid was found in larvae fed with walnut.•Manipulation of fatty acids in insect diet could potentially impact their fitness.
The activity coefficients at infinite dilution,
γ
13
∞
for 32 solutes: alkanes, alken-1-es, alkyn-1-es, cycloalkanes, aromatic hydrocarbons, alcohols, thiophene, tetrahydrofuran,
tert-butyl methyl ...ether, and water in the ionic liquid 1-butyl-3-methylimidazolium thiocyanate BMIMSCN were determined by gas-liquid chromatography at the temperatures from 298.15
K to 368.15
K. The values of the partial molar excess enthalpies at infinite dilution
Δ
H
1
E
,
∞
were calculated from the experimental
γ
13
∞
values obtained over the temperature range. The selectivities for the hexane/benzene, cyclohexane/benzene, hexane/thiophene, and other separation problems were calculated from the
γ
13
∞
and compared to the other ionic liquids,
N-methyl-2-pyrrolidinone, and sulfolane, taken from the recent literature. This work demonstrates that with chosen ionic liquid it is possible to separate different organic compounds with the highest selectivity, ever published.
The present work focussed on application of the environmental friendly 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide (BMIM+Tf2N−) ionic liquid for the separations of ...(alkane/aromatic), (alkane/alk-1-ene), (cycloalkane/aromatic) and (water/alkan-1-ol) using gas-liquid chromatography (GLC) technique. In this reason the activity coefficients at infinite dilution, γ13∞, for 31 organic solutes (alkanes, cycloalkanes, alkenes, alkynes, aromatics, alkanol and ketones) and water in ionic liquid were measured at temperatures of (323.15, 333.15, 343.15, 353.15 and 363.15) K. Stationary phase loadings of (42.83 and 68.66) % by mass were used to ensure repeatability of measurements. Density and viscosity values were measured to confirm the purity of ionic liquid. Partial molar excess enthalpies at infinite dilution, ΔH1E,∞, were also determined. The selectivities, Sij∞, and capacities, kj∞, were determined for the above separations. The separating ability of the investigated ionic liquid was compared with previously investigated ionic liquids and industrial solvents such as sulfolane, n-methyl-2-pyrrolidine (NMP) and n-formylmorpholine (NFM).
•Activity coefficients were measured in the ionic liquid BMIM+Tf2N−.•Selectivities for selected separations compared to other IL's and solvents•Capacities for selected separations were also calculated and discussed.•The expression and estimation of uncertainty have been described in detail.
Introduction: Comprehensive analysis is necessary to analyze the widespread use of bisphosphonate drugs in the treatment and prevention of various diseases of connective tissue structures. The ...relevance of the study depends on the impact they have on the patient’s somatic condition, given the number of early and late complications diagnosed by domestic and foreign clinicians. Materials and methods: The methodology used was developed on Stavropol Regional Clinical Hospital from 2010 to 2022. A randomized and observational study of the state of connective tissue structures was conducted in 186 patients who had a history of taking zoledronic acid and developed bisphosphonate osteonecrosis of the jawbone. At the diagnostic and treatment stages, patients were tested using laboratory methods to monitor amino acids in biological fluids (blood), as well as bone blocks extracted intraoperatively using highly effective gas-liquid chromatography on AAA 500. Results and discussion: Aminograms obtained in the pre-operative period indicate toxic effects of zoledronic acid on neuro, endocrine, and other human systems. The initiation and progression of aseptic inflammatory processes in tissue structures is correlated with the deteriorating general ocular status of patients when amino acids, such as alanine, serine, taurine, phenylalanine, tyrosine, proline, histidine, glycine, and valine, against a background of 90.4±2.1 mmol/L ammonia are reduced critically. Conclusion: Zoledronic acid initiates an aseptic chronic inflammatory process in the jaw bones, accompanied by toxic acidosis, which worsens osteoporotic symptoms.
Background
. Studying essential oils in conifers is of great scientific and practical interest due to their high bactericidal properties. Their volatiles play an important role in combating ...pathogenic microflora and removing harmful microorganisms from the air, thus benefiting human health. Conifers are highly effective as part of parklands and urban landscaping.
Materials and methods
.
Pinus radiata
D. Don,
P. sabiniana
Douglas and
P. coulter
i D. Don grown on the Southern Coast of Crimea were studied. Essential oil was extracted from pine needles by hydrodistillation on Ginsberg devices, and its component composition was analyzed using gas–liquid chromatography on a 6890N system with a 5973N mass selective detector.
Results.
Among the studied species, P.
radiata
manifested high essential oil content in needles: 0.15% on the wet weight basis (0.36%, dry weight). Under the conditions of the southern coast of Crimea, the major essential oil components in P. r
adiata
were β-pinene (29.5% of the total essential oil), α-pinene (21.2%) and limonene (12.4%); in P.
sabiniana
, phenylethyl butyrate (20.5%), limonene (15.2%) and α-pinene (13.7%); in P.
coulteri,
β-pinene (11.6%), δ-cadinene (11.0%) and α-pinene (10.6%). In the essential oil of P.
radiata
monoterpenes dominated (74.9%); in P.
sabiniana
, monoterpenes (38.7%) and their derivatives − alcohols (25.3%) and esters (20.5%); in P. coulteri, sesquiterpenes (38.2%) and monoterpenes (28.8%).
Conclusion
. The essential oils of P.
radiata
and P.
sabiniana
under different climate conditions contained mostly monoterpenes (β-pinene in P.
radiata
, and α-pinene in P.
sabiniana)
and their derivatives. The component composition of P.
coulteri
essential oil was the most variable, with a general tendency towards the predominance of sesquiterpenes and diterpenes; the ratio between those groups and the qualitative composition of sesquiterpenes both varied.
Doxylamine is a hypnotic medicine used for treatment of minor sleep disorders and is a frequent cause of poisoning. Aim. To develop GLC/MS-procedure of doxylamine quantification and carry out ...step-by-step validation of the developed procedure in the variants of the method of calibration curve, method of standard and method of additions. Results. The chromatographic conditions have been chosen for doxylamine determination by the method of GLC with mass-spectrometry detection with temperature program changing during the analysis from 70 °C to 320 °C. Retention time for doxylamine is 14.53 min. To prove the possibility of the proposed procedure application in further analysis its validation has been carried out in the variants of the method of calibration curve, method of standard and method of additions. Such validation parameters as in process stability, linearity, accuracy, precision and limit of determination have been estimated by model solutions. Experimental part. Conditions of chromatographic analysis: Agilent 6890N/5973N/7683; НР-5MS ∅0.25 mm × 30 m, 0.25 μm; DB-17MS ∅0.25 mm × 30 m, 0.15 μm; columns are connected sequentially through Deans switch; thermostat – 70 CºС (2 min), 45 ºС/min to 210 ºС, 6 ºС/min to 320 ºС (12.56 min); transfer line – 280 ºС; ion source – 230 ºС; quadrupole – 150 ºС; electron impact, 70eV; 40 – 750 m/z; injector – 250 ºС; splitless mode; inlet carrier gas (helium) pressure: 1st column – 26.06 psi, 2nd column – 19.30 psi. Conclusions. New procedure of doxylamine quantitative determination by the method of GLC/MS has been developed. Its validation has been carried out and acceptability for application has been shown.
The content of triacylglycerols (TAG) in krill oil is generally omitted from the labels of commercial supplements and unacknowledged in studies aimed at proving its health benefits. The present study ...demonstrates that TAG compounds, in addition to phospholipids and lysophospholipids, are an important lipid class in pure krill oil. The fatty acid composition of TAG molecules from krill oil and their distribution on the backbone of TAG structures were determined by gas chromatography and liquid chromatography tandem mass spectrometric, respectively. The content of omega 3 polyunsaturated fatty acids (n-3 PUFA) was similar to those reported in the literature for fish oil. It was estimated that 21 % of n-3 PUFA were at the
sn
-2 position of TAG structures. To our knowledge, this is the first determination and structural characterization of TAG in pure krill oil supplements.
A new ionic liquid was chosen for the separation of aromatic hydrocarbons from aliphatic hydrocarbons. The activity coefficients at infinite dilution,
γ
13
∞
for 29 solutes: alkanes, alkenes, ...alkynes, cycloalkanes, aromatic hydrocarbons, alcohols, and water in the ionic liquid 1-ethyl-3-methyl-imidazolium thiocyanate EMIMSCN were determined by gas–liquid chromatography at the temperatures from 298.15
K to 368.15
K. The values of the partial molar excess enthalpies at infinite dilution
Δ
H
1
E,
∞
were calculated from the experimental
γ
13
∞
values obtained over the temperature range. The selectivities for the hexane/benzene and cyclohexane/benzene separation problems were calculated from the
γ
13
∞
and compared to the other ionic liquids, NMP and sulfolane, taken from the recent literature. This work demonstrates that with chosen ionic liquid it is possible to separate different organic compounds with the highest selectivity ever published.
Metabolite profiling of gochujangs (Korean fermented red pepper paste) produced from different kinds of raw materials (WG, wheat gochujang; RG, rice gochujang) was performed using gas chromatography ...time-of-flight mass spectrometry (GC–TOF-MS) and ultra-performance liquid chromatography quadrupole time of flight mass spectrometry (UPLC-Q-TOF-MS). Using principal component analysis (PCA), gochujang samples were differentiated based on the differences in starchy source and secondary materials used in their production. The content of amino acids and sugars was higher in WG, whereas the content of flavonoids, soyasaponins, and γ-aminobutyric acid (GABA) was higher in RG. The content of flavonoids and soyasaponins was related to the higher soybean koji content of RG. The level of antioxidant activity in WG was higher than that in RG and showed a strong positive correlation with amino acid content and a negative correlation with flavonoid content. Although the Trolox equivalent antioxidant capacity of flavonoids was only 10-fold higher than that of amino acids in an antioxidant activity assay, the total amino acid content was as much as several hundred fold higher than total flavonoid content in gochujang. This result suggests that the amino acids could be a main contributor to the antioxidant capacity in gochujang.
Display omitted
•The starch koji used in the production of gochujang affected the metabolites produced.•The wheat gochujang showed higher antioxidant activity than did rice gochujang.•The amino acids in gochujang had a stronger correlation with antioxidant activity than did flavonoids.
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