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Cu(II) ion was selected as an additive to improve the enantioseparation efficiency of three dihydroflavone enantiomers in high-speed counter-current chromatography (HSCCC), using hydroxypropyl-β-cyclodextrin (HP-β-CyD) as the chiral selector. The influences of important parameters, including the metal ion, the concentrations of HP-β-CyD and the Cu(II) ion, and the sample size were investigated. Under optimal conditions, three dihydroflavone enantiomers, including (±)-hesperetin, (±)-naringenin, and (±)-farrerol, were successfully enantioseparated. The chiral recognition mechanism was investigated. The enantioseparation was attributed to the different thermodynamic stabilities of the binary complexes of HP-β-CyD and (±)-hesperetin, and Cu(II) ion could enhance this difference by forming ternary complexes with the binary complexes. This Cu(II) ion-improved complexation HSCCC system exhibited improved performance for chiral separation, and therefore it has great application potential in the preparative enantioseparation of other compounds with similar skeletons. [ABSTRACT FROM AUTHOR]

Cu(II) complexed amino acid ionic liquid, Cu(II)-[1-butyl-3-methylimidazolium][L-Pro] (Cu(II)-[BMIm][L-Pro]), was successfully adopted as chiral ligand to improve the enantioseparation efficiency in high speed counter-current chromatography (HSCCC). For the enantioseparation of intractable naringenin (NRG) racemic mixtures, Cu(II)-[BMIm][L-Pro] coupled with hydroxypropyl-β-cyclodextrin (HP-β-CD) was successfully applied as dual chiral selectors in HSCCC. The influence of important parameters, including the concentration of the chiral selectors, the pH value, and the temperature were investigated. Under optimal conditions, 4.5 mg of (+)-NRG and 4.1 mg of (−)-NRG were successfully separated from 10 mg NRG racemic mixtures with the purity of 98%. The chiral recognition mechanism of dual chiral selectors was illuminated by the UV–vis and NMR spectra, suggesting that the enantioseparation was upon the difference of the thermodynamic stability of the quaternary complexes of Cu(II), [BMIm][L-Pro], HP-β-CD, and NRG. The results illustrated that the developed HSCCC system, based on the synergistic mechanism of Cu(II)-[BMIm][L-Pro] and HP-β-CD, exhibited better performance on enantioseparation and had great application potential in preparative chiral separation of natural products. [ABSTRACT FROM AUTHOR]

The use of a dinuclear Cu 2 (II)-β-cyclodextrin complex (Cu 2 -β-CyD) as a chiral selector (CS) was successfully applied to chiral high speed counter-current chromatography (HSCCC) for the enantioseparation of aromatic α-hydroxycarboxylic acids. α-cyclohexylmandelic acid (CHMA) as a case was studied to optimize the separation temperature, the pH value of the aqueous phase, and the concentration of the chiral selector, which were comparatively studied between Cu 2 -β-CyD and native β-cyclodextrin (β-CyD) as CSs. The thermodynamic parameters of the formation of the complex between the enantiomers and the CSs were obtained, and the complex formation constants between the enantiomers and Cu 2 -β-CyD or β-CyD were determined using induced circular dichroism technology. The results indicate that Cu 2 -β-CyD can remarkably improve the enantioseparation compared with β-CyD, mainly due to the ion-pairing interactions between the deprotonation of carboxyl group of CHMA and the Cu(II) ion of Cu 2 -β-CyD. Five of other aromatic α-hydroxycarboxylic acids were also enantioseparated successfully by HSCCC using Cu 2 -β-CyD as a CS. [ABSTRACT FROM AUTHOR]

Highlights: [•] A new method for chiral separation of TVN racemate using HSCCC was established. [•] Induced circular dichroism was first applied to optimize the chiral HSCCC conditions. [•] This method could be applied to improve the production rate of the chiral separation. [ABSTRACT FROM AUTHOR]

Highlights: [•] Hg2+, MeHg, EtHg and PhHg were separated on two sequential 12.5-mm SCX columns. [•] The shortest separation time (2–2.5min) was consumed. [•] The mobile phase was most environment-friendly and fairly compatible with ICP-MS. [ABSTRACT FROM AUTHOR]

Abstract: This work reports a new sensitive multi-residue liquid chromatography–tandem mass spectrometry (LC–MS/MS) method for detection, confirmation and quantification of six neonicotinoid pesticides (dinotefuran, thiamethoxam, clothiandin, imidacloprid, acetamiprid and thiacloprid) in agricultural samples (chestnut, shallot, ginger and tea). Activated carbon and HLB solid-phase extraction cartridges were used for cleaning up the extracts. Analysis is performed by LC–MS/MS operated in the multiple reaction monitoring (MRM) mode, acquiring two specific precursor-product ion transitions per target compound. Quantification was carried by the internal standard method with D4-labeled imidacloprid. The method showed excellent linearity (R 2 ≥0.9991) and precision (relative standard deviation, RSD≤8.6%) for all compounds. Limits of quantification (LOQs) were 0.01mgkg−1 for chestnut, shallot, ginger sample and 0.02mgkg−1 for tea sample. The average recoveries, measured at three concentrations levels (0.01mgkg−1, 0.02mgkg−1 and 0.1mgkg−1 for chestnut, shallot, ginger sample, 0.02mgkg−1, 0.04mgkg−1 and 0.2mgkg−1 for tea sample), were in the range 82.1–108.5%. The method was satisfactorily validated for the analysis of 150 agricultural samples (chestnut, shallot, ginger and tea). Imidacloprid and acetamiprid were detected at concentration levels ranging from 0.05 to 3.6mgkg−1. [Copyright &y& Elsevier]

• Presenting an overview of MS in cosmetic analysis over the past two decades. • Detailed demonstration of current sample preparation and ionization techniques. • Offering a concise outlook on future development of MS in cosmetic analysis. Mass spectrometry (MS) is a crucial tool in cosmetic analysis. It is widely used for ingredient screening, quality control, risk monitoring, authenticity verification, and efficacy evaluation. However, due to the diversity of cosmetic products and the rapid development of MS-based analytical methods, the relevant literature needs a more systematic collation of information on this subject to unravel the true potential of MS in cosmetic analysis. Herein, an overview of the role of MS in cosmetic analysis over the past two decades is presented. The currently used sample preparation methods, ionization techniques, and types of mass analyzers are demonstrated in detail. In addition, a brief perspective on the future development of MS for cosmetic analysis is provided. [ABSTRACT FROM AUTHOR]

Highlights • Chiral CCC was superior to HPLC for preparative separation of synephrine. • pH-zone-refining CCC allowed efficient preparative enantioseparation of synephrine. • pH-zone-refining CCC was suited for preparative resolution of β-amino alcohols. Abstract Synephrine, a chiral adrenergic agonist, exists as R - (more active) and S -enantiomers (less active) that are difficult to separate because of their alkalinity and high polarity. Herein, we show that although this enantioseparation can hardly be achieved by high-performance liquid chromatography, acceptable preparative separation can be realized using high-speed counter-current chromatography (HSCCC) and pH-zone-refining counter-current chromatography (CCC) under optimal conditions. Specifically, 23.0 mg of S -synephrine and 25.0 mg of R -synephrine were isolated from 60.0 mg of racemic synephrine by conventional HSCCC, while 70.0 mg of S -synephrine and 69.0 mg of R -synephrine were obtained from 200.0 mg of racemic synephrine by pH-zone-refining CCC. The pH-zone-refining CCC was identified as the most efficient enantioseparation technique for synephrine and can be applied for the preparative enantioseparation of other β-amino alcohols. [ABSTRACT FROM AUTHOR]

• A new strategy for precise separation of lysine-specific demethylase 1 inhibitors • Multi-mode CCC separation guided by molecular docking and LC-MS/MS analysis • The PH-zone refining and recycling CCC separation finished by only one instrument • Compound 3 showed the potential ability of prohibiting tumor invasion and metastasis It is significant to precisely isolate potential active compounds from medicinal herbs containing multiple compounds. Herein, a new strategy for precise separation of lysine-specific demethylase 1 (LSD1) inhibitors from the rhizome of Corydalis yanhusuo (RCY) using counter-current chromatography (CCC) guided by molecular docking and liquid chromatography-mass spectrometry/mass spectrometry (LC-MS/MS) analysis was established. First, representative alkaloids from RCY were docked with LSD1 for screening active skeleton compounds. Simultaneously, the crude extract of RCY was preliminarily separated via pH-zone refining CCC. Subsequently, guided by LC-MS/MS analysis of the fragmentation pathways, three potential active fractions were obtained, followed by further online-storage and recycling CCC separation. Finally, three high-purity target quaternary alkaloids compound 3 (dehydrocorydaline) , 7 (coptisine) , and 8 (columbamine) were successfully isolated as a new class of potential natural LSD1 inhibitors by only one CCC instrument with multiple modes. Compound 3 , with the highest LSD1 inhibition ratio of 2.44 μ M, was tested for its ability to inhibit tumor invasion and metastasis in U2OS cells. Therefore, the CCC separation guided by virtual screening is a promising method for the targeted isolation of enzyme inhibitors from medicinal herbs. [ABSTRACT FROM AUTHOR]