A Type of Stable Amides Behaves as Acyl Transfer Reagents upon Visible-Light Irradiation through Self-aromatization.

Organic molecules with light-modifiable reactivity are important in many fields because they can serve as the "switch" for light to trigger chemical processes. Herein, we disclose a new type of stable non-twisted amides, the reactivity of which can be turned on by light as acyl transfer reagents. Upon photo-activation, these amides react with various nucleophiles including amines, phenols, hydroxide, thiols, boronic acids, and alkynes either under metal-free or metal-catalysis conditions. This reactivity hinges on the design and synthesis of a photo-activatable reagent (7-nitro-5,6-dihydrophenanthridine), which undergoes self-aromatization enabled by an internal oxidant under light. This masked acyl donor group is anticipated to be useful in scenarios where light is preferred to trigger a chemical process.

[Simultaneous determination of 28 fragrance components in cosmetics by gas chromatography-tandem mass spectrometry].

With the increasing number of cosmetic products, their flavor and fragrance components are receiving greater and greater attention. Establishing an analytical method of determining these components in cosmetics is one of the most effective measures to eliminate consumers' concerns. In this study, a method for the simultaneous determination of 28 fragrance residues in cosmetics by gas chromatography-tandem mass spectrometry (GC-MS/MS) was developed. The samples were extracted using methanol and those containing more oil and grease were purified using a neutral alumina solid-phase extraction column, whereas those with more complex compositions were purified by QuEChERS. The analytes in the samples were measured by GC-MS/MS, characterized using their retention times and characteristic ion pairs, and quantified with an external standard. The respective limits of detection (LODs, S/N=3) and quantification (LOQs, S/N>10) of the compounds were in the ranges 2-20 and 5-50 µg/kg. The linearities of the concentration curves of the 28 substances were good in the ranges 1-100, 2-200, 4-200, and 10-1000 µg/L, and the correlation coefficients of the quantitative ion pairs were >0.999. Twenty-eight fragrances were added to blank samples at spiked levels of 50-500 µg/kg, and the recoveries ranged from 71.3% to 120.4%, with RSDs of 1.5%-14.6%. The method could be applied in the determination of fragrances in cosmetics because it was simple, sensitive, and stable and could effectively exclude the interferences of complex matrices. The method was used to determine the fragrance components in 16 cosmetic products, and some fragrance components were detected in 12 samples. Increased attention should be paid to the safeties of fragrances and flavors used in cosmetics.

Suspect screening and untargeted analysis of veterinary drugs in food by LC-HRMS: Application of background exclusion-dependent acquisition for retrospective analysis of unknown xenobiotics.

The presence of veterinary drug and pesticide residues in food products pose considerable threats to human health. Monitoring of these residues in food is mainly carried out using targeted analysis by triple quadrupole mass spectrometry. However, these methods are not suitable for suspect screening and untargeted analysis of unknowns. The main objectives of this study were to develop a new high-resolution mass spectrometry (HRMS)-based analytical strategy for retrospective analysis of suspect and unknown xenobiotics and to evaluate its performance in the tentative identification of 48 veterinary drugs as "unknowns" spiked in a pork sample. In the analysis, a newly developed background exclusion data-dependent acquisition (BE-DDA) technique was employed to trigger the product ion (MS/MS) spectral acquisition of the "unknowns", and an in-house precise-and-thorough background-subtraction (PATBS) technique was applied to detect these "unknowns". Results showed that untargeted data mining of the acquired LC-MS dataset by PATBS was able to find all the 48 veterinary drugs and 46 of them were triggered by BE-DDA to generate accurate MS/MS spectra. The dataset of recorded accurate full-scan mass and MS/MS spectra of all the xenobiotics of the test pork sample is defined as the xenobiotics profile. Searching the xenobiotic profile of the test pork sample using mass spectral data of selected veterinary drugs (as suspects) from the mzCloud spectral library led to the correct hits. Searching against the mzCloud spectral library using the mass spectral data of selected individual veterinary drugs (as unknowns) from the xenobiotics profile tentatively confirmed their identities. In contrast, analysis of the same sample using ion intensity-data dependent acquisition only recorded the MS/MS spectra for 34 veterinary drugs. In addition, a data independent acquisition method enabled the acquisition of the fragment spectra for 44 veterinary drugs, but their spectral data displayed only one or a few true product ions of individual analytes of interest along with many fragments from coeluted biological components and background noises. This study demonstrates that this analytical strategy has a potential to become a practical tool for the retrospective suspect screening and untargeted analysis of unknown xenobiotics in a biological sample such as veterinary drugs and pesticides in food products.

Extraction for profiling free and bound phenolic compounds in tea seed oil by deep eutectic solvents.

Bound phenolic compounds have rarely been reported in vegetable oils and this may be due to little research about the extraction. Deep eutectic solvents (DESs), recently applied in the extraction of phenolic compounds as alternatives to organic solvents, were adopted in the extraction of free and bound phenolic compounds from tea seed oil in this work. First, the phenolic compounds were analyzed by ultra-high-performance liquid chromatography with quadrupole-time-of-flight and triple-quadrupole tandem mass spectrometry (UHPLC-Q-TOF-MS/MS) for characterization and UHPLC-QqQ-MS/MS for quantification and 25 phenolic compounds were found to exist in both free and bound forms. Then, DESs were screened for extraction of free and bound phenolic compounds from tea seed oil as the pretreatment for analysis and the results showed that hydrogen bond donors (HBDs) and temperature significantly affected the extraction efficiency of DESs. Finally, free phenolic compounds (83.91 µg/g) and bound phenolic compounds (25.71 µg/g), extracted by the DES with glycerol as HBD at 50 °C, were 51.0% and 93.2% higher than those extracted by methanol/water (60%, v/v), respectively. This work not only advanced the basic data of phenolic compounds in tea seed oil but also explored an efficient extraction method for scientific analysis of free and bound phenolic compounds.

[Simultaneous determination of 21 illegally added compounds in health foods by ultra high performance liquid chromatography-tandem mass spectrometry with solid phase extraction].

A rapid method for the simultaneous determination of 21 illegally added compounds in health foods was developed based on solid phase extraction (SPE) combined with ultra high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). After ultrasonic extraction with acetonitrile, the samples were purified on an HLB SPE column, separated on a Waters BEH C18 column (100 mm×2.1 mm, 1.7 µm) using 10 mmol/L ammonium acetate aqueous solution and methanol as the mobile phases. The compounds were detected by an electrospray ionization (ESI) source in positive ion mode with multi-reaction monitoring (MRM). The 21 illegal additives showed good linear relationships with correlation coefficients no less than 0.995. The limits of detection (LODs) were 3-160 µg/kg for different matrixes. The recoveries ranged from 61.8% to 109.3%, and the relative standard deviations ranged from 1.6% to 14.7%. The method can be used for the simultaneous determination of the illegally added drugs in the losing weight, lipid-lowering, anti-diabetic and anti-hypertension health foods.

Discrimination of the species and authenticity of Rhizoma Coptidis based on stable isotope and multielement fingerprinting and multivariate statistical analysis.

It is essential to be able to identify the source species and to determine the authenticity of traditional Chinese medicines (TCM) in order to prevent the use of false or inferior medicines. In this work, a stable and reliable method of discriminating among the three source species of Rhizoma Coptidis and checking the authenticity of Rhizoma Coptidis samples was established. The technique involved evaluating stable isotope ratios and the contents of multiple elements in samples along with the use of multivariate statistical techniques. The stable isotope ratios δ13C, δ15N, δ2H, and δ18O and the concentrations of various inorganic elements (Li, B, Na, Mg, Al, P, Si, K, Ca, Ti, Mn, Fe, Cu, Zn, Sr, and Ba) in authentic Rhizoma Coptidis samples from three source species (n = 56) and in counterfeit Rhizoma Coptidis samples (n = 39) were determined. The results showed that there were significant differences between the samples from different source species according to multivariate statistical analysis. The three species were clearly distinguished using hierarchical cluster analysis (HCA). Employing stepwise linear discriminant analysis (SLDA), a classification model for differentiating the three species was developed, and this model achieved 100% classification accuracy when applied to samples. In addition, authentic samples and counterfeit samples were successfully discriminated using stable isotope and multielement fingerprint analysis and orthogonal projections to latent structures discriminant analysis (OPLS-DA), and OPLS-DA models for checking the authenticity of Rhizoma Coptidis were established and verified. Therefore, stable isotope and multielement analysis combined with multivariate statistical analysis was shown to be a promising method of discriminating among the three source species of Rhizoma Coptidis and of establishing the authenticity of Rhizoma Coptidis samples. Graphical abstract.

A high efficient adsorbent for plant growth regulators based on ionic liquid and ß-cyclodextrin functionalized magnetic graphene oxide.

Four types of ionic liquids which composed of cation with imidazole ring and anion with benzene, naphthalene, anthraquinone and naphthoquinone ring were prepared and named VOIm+BenSO3-, VOIm+NapSO3-, VOIm+AQSO3- and VOIm+NQSO3-, respectively. Then, ionic liquids and ß-cyclodextrin functionalized magnetic graphene oxide materials were firstly synthesized for the extraction of 23 plant growth regulators in vegetable samples. The synthesized materials anticipated the unique properties of ionic liquids, ß-cyclodextrin, graphene oxide and Fe3O4@SiO2, including high surface area, high supramolecular recognition capability, superparamagnetism and large delocalized π-electron system, which were successfully characterized. Among four kinds of ionic liquids functionalized adsorbents, the VOIm+AQSO3- modified material exhibited high adsorption capability to 7 plant growth regulators compared with Fe3O4@SiO2/GO/ß-CD, Fe3O4@SiO2/GO and other three types of ionic liquids based adsorbents. Parameters that could affect the recoveries of 7 plant growth regulators were investigated, such as mass ratio of Fe3O4@SiO2/GO/ß-CD to ionic liquids, salt concentration, pH, amount of adsorbent, extraction time and desorption solvent. Under the optimal condition, the magnetic solid phase extraction method using VOIm+AQSO3- and ß-cyclodextrin functionalized magnetic graphene oxide material (Fe3O4@SiO2/GO/ß-CD/IL) as adsorbent was developed and coupled with ultra-high performance liquid chromatography-triple quadrupole linear ion trap mass spectrometry for the determination of 7 plant growth regulators in vegetable samples. Validation results showed that the limit of detection and limit of quantitation were in the range of 0.01-0.18 µg/kg and 0.03-0.58 µg/kg, respectively. The satisfactory linearities were acquired in the concentration of 2-50 µg/kg with the correlation coefficients higher than 0.9982. Taken together, the synthesized Fe3O4@SiO2/GO/ß-CD/IL was a highly effective magnetic solid phase extraction adsorbent for the enrichment of trace level of plant growth regulators in vegetable samples.

Controllable synthesis of magnetic nanoporous carbon with tunable porosity for the efficient cleanup of vegetable samples.

Highly graphitic nanoporous carbon (NPC) was obtained from an agricultural waste-citrus peel at optimum condition. Then, a low-cost and pore size-controlled magnetic graphitic nanoporous carbon (MNPC) with ultrahigh specific surface area (1064 m2 g-1) was successfully fabricated by coprecipitation of Fe3O4 particles onto NPC. The prepared MNPC was characterized by Brunauer-Emmett-Teller (BET), Raman spectrum, scanning electron microscope (SEM) and Fourier transform infrared spectrometry (FT-IR). BET results showed a significant increase in the micropores volume and specific surface area of MNPCs following the increase of carbonization temperature, which implied that highly efficient carbonization made NPC an excellent active phase for MNPC. Besides, the adsorption mechanism was investigated and turned out that π-π interactions between interfering substances and MNPC were considered to be the major driving force for the adsorption process. The experimental parameters affecting the cleanup efficiency was optimized through Response surface methodology (RSM) in detail. Under the optimal cleanup condition, the MNPC was applied for determination of 16 insecticides in vegetables coupled with gas chromatography-mass spectrometry (GC-MS), a satisfactory performance was obtained. Good linearity was observed in the investigated concentration range of 1-100 µg kg-1 with correlation coefficients (r2) between 0.9963 and 0.9999. The limits of detection (LODs) were in the range of 0.03-0.33 µg kg-1. The recoveries ranged from 81.9 to 112.3% with relative standard deviations (RSDs) less than 10.9%. To summary up, the MNPC could potentially be used as a super adsorbent to efficiently remove pigments from vegetables, so that the proposed method was an efficient cleanup and enrichment procedure.

Simultaneous determination of nine anticoagulant rodenticides by ultra-performance liquid chromatography-tandem mass spectrometry with ultrasound-assisted low-density solvent dispersive liquid-liquid microextraction.

A sensitive determination method is developed for nine anticoagulant rodenticides (ARs) in urine samples by ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) with ultrasound-assisted low-density solvent dispersive liquid-liquid microextraction (UA-LDS-DLLME) pretreatment. The target analytes are brodifacoum, bromadiolone, warfarin, coumachlor, coumatetralyl, difenacoum, pindone, diphacinone and chlorophacinone. The parameters that influence the extraction recovery in the UA-LDS-DLLME were systematically investigated and optimized. With the optimized extraction parameters, recoveries ranging from 64.6%-124.2% were obtained for the target analytes. The linear range for all analytes was 0.1-100 ng/mL with correlation coefficients higher than 0.99. Very low LODs ranging in 0.003-0.03 ng/mL were obtained. LOQs were in the range of 0.01-0.1 ng/mL for the nine target analytes. The accuracy that was expressed as mean relative error was within ±5.8% while the precision expressed as relative standard error was less than 5.9%. The combination of UA-LDS-DLLME with UPLC-MS/MS is a feasible, sensitive and rapid analytical approach for the determination of ARs in urine matrix, which is particularly suitable for clinical and forensic purposes.

A highly anti-selective asymmetric Henry reaction catalyzed by a chiral copper complex: applications to the syntheses of (+)-spisulosine and a pyrroloisoquinoline derivative.

A highly anti-selective asymmetric Henry reaction has been developed, affording synthetically versatile ß-nitroalcohols in a predominately anti-selective manner (mostly above 15:1) and excellent ee values (mostly above 95%). Moreover, the anti-selective Henry reaction was carried out in the presence of water for the first time with up to 99% ee. The catalytic mechanism was proposed based on the detection of the intermediates by extractive electrospray ionization mass spectrometry (EESI-MS). Furthermore, the anti adducts have been successfully transformed into the biochemically important (+)-spisulosine and a pyrroloisoquinoline derivative.