•First paper reporting the use of CSP chemically bonded to core–shell material.•The advantages of core–shell material for fast separation of enantiomers are shown.•Comparison between CSP based on ...fully and superficially porous material is shown.
This work reports a comparison of HPLC separations of enantiomers with chiral stationary phases (CSPs) prepared by chemically bonding cyclofructan-6, functionalized with isopropyl carbamate groups on fully and superficially porous particles (SPPs). The chromatographic performance of the superficially porous CSP based column was compared with columns packed with 5μm and 3μm fully porous particles (FPPs). At a flow rate of 3.0mL/min the number of plates on column afforded by the SPP column was ∼7× greater than the number of plates on column (same length) obtained when using the 5μm FPP based column. The flow rate providing the highest efficiency separation was ∼1.0mL/min for the SPP column while it was ∼0.5mL/min for both FPP columns. It was found that the selectivity and resolution of the separations were comparable between fully porous and superficially porous based columns (under constant mobile phase conditions), even though the SPP column contained lower absolute amounts of chiral selector. When tested under constant retention conditions, the SPP based CSP greatly improved resolution compared to the FPP based columns. At high flow rates the efficiency gained by using superficially porous CSP was accentuated. The advantages of columns based on SPPs become more obvious from the viewpoint of plate numbers and resolution per analysis time.
Lavandula angustifolia (LaEO) essential oil has been widely used by aromatherapy in the treatment of various clinical conditions, with evidence of its analgesic and anti-inflammatory potential. Our ...results demonstrate that sixty-five substances were identified in LaEO. Among the compounds found, the major ones were linalool (30.61%) and linalyl acetate (20.36%). We found that LaEO inhalation reduces mechanical hyperalgesia in conditions of chronic inflammatory and neuropathic pain. Furthermore, this effect seems to be mediated by peripheral and central opioid and cannabinoid 2 receptors. The findings of the present study suggests that the LaEO inhalation is effective on the chronic pain treatment.
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•Inhalation of LaEO is effective in alleviating symptoms of pain in mice models of chronic pain.•Activation of peripheral and spinal opioid receptors is involved in the antihyperalgesic effect of Inhalation of LaEO.•Activation of peripheral and spinal CB2 receptors is involved in the antihyperalgesic effect of Inhalation of LaEO.
The study of host–guest complexation between reactive 2-carboxyphthalanilic acid (CPA) and two cationic pillararenes has been carried out. Host–guest complexation with significant kinetic effects was ...observed only with the smaller cavity size pillararene (P5A). Kinetics in the pH range 1.50–6.40, ESI–MS, 1H NMR titration, and ROESY experiments were performed to characterize the complexes. High binding stoichiometry (H:G2) was observed for all CPA protonation states. The system is pH-dependent, and inversion of cooperativity (negative to positive) occurs by increasing the dianionic CPA2– concentration (allosteric behavior). Toward physiological pH, association constant K 1:1 does not change (104 M–1), and K 1:2 increased from 102 to 104 M–1, as well as the inhibitory effect increased up to 222-fold. NMR results elucidated the structure of the complex and allowed us to create a map of H–H interactions that describes well the diversity and number of interactions in the complex.
This paper reports the development of a fast separation method employing capillary zone electrophoresis for the simultaneous determination of hippuric acid, mandelic acid, and creatinine in samples ...of urine using a coated capillary. The background electrolyte was composed of 10 mmol L
−1
tris(hydroxymethyl)aminomethane and 30 mmol L
−1
2-hydroxy-isobutyric acid at pH 3.6. The internal standard was 3,5-dihydroxybenzoic acid. Separations were performed in a fused silica capillary (32 cm total length, 8.5 cm effective length, and 50 μm internal diameter) coated with crosslinked hydroxypropyltrimethyl ammonium chloride chitosan and κ-carrageenan. Direct UV detection was performed at a wavelength of 200 nm. Samples and standards were injected hydrodynamically (−50 mbar, 3 s) using the short-end injection procedure. The electrophoretic system was operated under constant voltage of 30 kV with positive polarity on the injection side. The separation time for hippuric acid, mandelic acid, and creatinine was less than 70 s. The evaluation of some analytical parameters of the method for the three analytes showed good linearity (
R
2
> 0.99), limit of detections of 0.21 to 0.63 mg L
−1
, inter-day precision better than 3.0% (peak area), and recovery in the range of 98 to 106%. The method developed was applied in the analysis of the three analytes in urine samples.
Graphical Abstract
New method using capillary zone electrophoresis for analysis of creatinine, hippuric acid and mandelic acid in urine
Cedrus atlantica essential oil (CaEO) presents analgesic and anti-inflammatory sedative properties. However, it remains unknown whether CaEO alleviates acute postoperative pain.
Here, we investigated ...the effect of CaEO on postoperative pain and its mechanisms related to the descending pain control in Swiss males mice induced by a plantar incision surgery (PIS) in the hindpaw.
Inhalation of CaEO (5′, 30′ or 60′) markedly reduced mechanical hypersensitivity. This effect was prevented by pre-treatment with naloxone or p-chlorophenylalanine methyl ester (PCPA, 100mg/kg, i.p.)-induced depletion of serotonin. In addition, p-alpha-methyl-para-tyrosin (AMPT, 100mg/kg, i.p.)-induced depletion of norepinephrine, intraperitoneal injection of the α2-adrenergic receptor antagonist yohimbine (0.15mg/kg, i.p.) or haloperidol (1mg/kg, i.p.) an antagonist of dopaminergic (D1 and D2) receptors prevented the effect of CaEO on hypersensitivity.
These findings suggest that CaEO alleviates postoperative pain by activating the descending pain modulation pathways on the opioidergic, serotonergic, noradrenergic (α2-adrenergic) and dopaminergic (dopamine D1 and D2 receptors) systems.
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•New HILIC column based on native CF6 bonded to superficially porous particles.•Efficiency up to 3.7 times higher than stationary phases with fully porous particles.•Analysis time up to 85% faster ...than using columns made with fully porous particles.
A new HILIC stationary phase comprised of native cyclofructan-6 (CF6) bonded to superficially porous silica particles (2.7μm) was developed. Its performance was evaluated and compared to fully porous silica particles with 5μm (commercially available as FRULIC-N) and 3μm diameters. Faster and more efficient chromatography was achieved with the superficially porous particles (SPPs). The columns were also evaluated in the normal phase mode. The peak efficiency, analysis time, resolution, and overall separation capabilities in both HILIC and normal phase modes were compared. The analysis times using the superficially porous based column in HILIC mode were shorter and the theoretical plates/min were higher over the entire range of flow rates studied. The column containing the superficially porous particles demonstrated higher optimum flow rates than the fully porous particle packed columns. At higher flow rates, the advantages of the superficially porous particles was more pronounced in normal phase separations than in HILIC, clearly demonstrating the influence that the mode of chromatography has on band broadening. However, the minimum reduced plate heights (hmin) were typically lower in HILIC than in the normal phase mode. Overall, the superficially porous particle based CF6 column showed clear advantages over the fully porous particle columns, in terms of high throughput and efficient separations of polar compounds in the HILIC mode.
This paper presents the Outer Plug Standardization – OPS, a novel technique as an alternative for the classic internal standardization using multiple injection in capillary zone electrophoresis is ...proposed herein. This technique was applied in a new method for the determination of chloride, nitrate and sulfate in rainwater samples. After the injection accuracy was tested and proved to be a minor error source (average 1.26% RSD), the OPS was applied and it improved the intra-day and inter-day precision of the analytical method by 32.5% and 24.7%, respectively. Using a capillary with effective length of 23.5 cm the electrophoretic separation of the three inorganic anions could be achieved in <1 min, with detection limits of 0.05, 0.09 and 0.11 mg L−1 for chloride, nitrate and sulfate, respectively. Also, the statistical t-test was applied to the results obtained for 82 rainwater samples that were collected and analyzed applying both the method developed in this study and the official APHA 4140 method where no statistical difference was noted within a 95% confidence level.
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•The analyte itself is used in the place of an internal standard.•Precision was improved in 24.6%–32.5% with the new internal calibration strategy.•Cl−, NO3− and SO42− were determined in less than 1 min.•The developed method showed good validation results.•Simple BGE with only 2 components.
For the first time, a procedure for simultaneous determination of the main artificial sweeteners, aspartame (ASP), cyclamate (CYC), saccharin (SAC), and acesulfame-K (ACSK) by a spectroscopic method ...associated with the multivariate calibration is proposed. These analytes were quantified in tabletop sweeteners samples using FT-Raman spectroscopy. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) was used as reference method. Partial least squares (PLS), interval PLS (iPLS), and synergism PLS (siPLS) methods were evaluated in a comparative study where the selected interval models presented better results. Multivariate regression models, such as PLS, iPLS and siPLS were built and the lower root mean square errors for prediction (RMSEP) found were 0.027–0.031% w/w, 0.316–0.363% w/w, 0.082–0.184% w/w, and 0.040–0.049% w/w to ASP, CYC, SAC, and ACSK, respectively. The coefficient of determination for prediction (R2p) varied between 0.978 and 0.979, 0.969–0.977, 0.952–0.994, and 0.959–0.965 for ASP, CYC, SAC and ACSK, respectively. The analysis of model's residues was made by bias and permutation tests to evaluate systematic and trend errors. The selected intervals by iPLS and siPLS were evaluated and the bands related to the vibrational modes of the analytes were assigned with the aid of density functional theory calculations (DFT).
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•The main artificial sweeteners were determined in powder tabletop sweeteners.•Liquid chromatography-tandem mass spectrometry was used as reference technique.•Raman spectroscopy was used as proposed analytical technique.•Chemometrics analysis by PLS, iPLS and siPLS was used to build prediction models.•DFT was used to calculate the frequencies to assign the spectral regions selected.
The aim of this study was to develop a simple and rapid method of capillary electrophoresis using a short end multiple injection in free solution to determine simultaneously the biological sample ...volume and analytes concentration. The method consists of a sequence of injection steps with an internal standard as the reference for correction of the volume of sample collected. The procedure was applies in the determination of NO
3
− and SCN in saliva samples. The background electrolyte was composed of 12
mM tris(hydroxymethyl)aminomethane and 8.5
mM sulfuric acid, at pH 2.5. The internal standard used was BrO
3
−. A fused silica capillary (48.5
cm total length, 8.5
cm effective length and 75
μm i.d.) coated with chitosan was used in a short-end injection configuration. Modification of the electroosmotic flow (EOF) using dynamic coating resulted in a controlled and stable EOF, contributing to the rapid separation of anions (0.36
min) in co-electroosmotic mode. The validation of the method for correcting the volume of saliva collected with a swab showed a difference of less than 3.5% compared with the predicted value and a correlation of 0.999. The limits of detection for NO
3
− and SCN
− were 0.13 and 0.23
mg
L
−1, respectively. The inter-day precision of the method determined for both analytes was less than 5% and the recovery ranged between 97 and 102%.
Many essential oils (EOs) of different plant species possess interesting antimicrobial effects on buccal bacteria and antioxidant properties. Eugenia klotzschiana Berg (pêra-do-cerrado, in ...Portuguese) is a species of Myrtaceae with restricted distribution in the Cerrado. The essential oils were extracted through the hydrodistillation technique using a modified Clevenger apparatus (2 hours) and chemically characterized by GC-MS. The major compounds were α-copaene (10.6 %) found in oil from leaves in natura, β-bisabolene (17.4 %) in the essential oil from dry leaves and α-(E)-bergamotene (29.9 %) in oil from flowers. The antioxidant activity of essential oils showed similarities in both methods under analysis (DPPH and ABTS˙+) and the results suggested moderate to high antioxidant activity. The antibacterial activity was evaluated by determining minimum inhibitory concentrations (MICs), using the microdilution method. MIC values below 400 µg/mL were obtained against Streptococcus salivarius (200 µg/mL), S. mutans (50 µg/mL), S. mitis (200 µg/mL) and Prevotella nigrescens (50 µg/mL). This is the first report of the chemical composition and antibacterial and antioxidant activities of the essential oils of E. klotzschiana. These results suggest that E. klotzschiana, a Brazilian plant, provide initial evidence of a new and alternative source of substances with medicinal interest.
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