In Situ Laser-Induced Breakdown Spectroscopy for Chromium Speciation Analysis Based on the Interactions of Oxygen-Containing Groups with Functionalized Co3O4-rGO: Evidence from Advanced Optical Techniques and Density Functional Theoretical Calculations under Electric Field.

Achieving accurate detection of different speciations of heavy metal ions (HMIs) in an aqueous solution is an urgent problem due to the different bioavailabilities and physiological toxicity. Herein, we nominated a novel strategy to detect HCrO4- and Cr(OH)2+ at a trace level via the electrochemical sensitive surface constructed by Co3O4-rGO modified with amino and carboxyl groups, which revealed that the interactions between distinct functional groups and different oxygen-containing groups of target ions are conducive to the susceptible and anti-interference detection. The detection sensitivities of 19.46 counts µg-1 L for HCrO4- and 13.44 counts µg-1 L for Cr(OH)2+ were obtained under optimal conditions, while the limits of detection were 0.10 and 0.12 µg L-1, respectively. Satisfactory anti-interference and actual water sample analysis results were obtained. A series of advanced optical techniques like X-ray photoelectron spectroscopy, X-ray absorption near-edge structure technology, and density functional theory calculations under an electric field demonstrated that chemical interactions between groups contribute more to the fixation of target ions than electrical attraction alone. The presence of oxygen-containing groups distinct from simple ionic forms was a critical factor in the selectivity and anti-interference detection. Furthermore, the valence cycle of Co(II)/(III) synergistically boosted the detection performance. This research provides a promising tactic from the microscopic perspective of groups' interactions to accomplish the precise speciation analysis of HMIs in the water environment.

Highly Stable Solid Contact Calcium Ion-Selective Electrodes: Rapid Ion-Electron Transduction Triggered by Lipophilic Anions Participating in Redox Reactions of CunS Nanoflowers.

Solid contact (SC) calcium ion-selective electrodes (Ca2+-ISEs) have been widely applied in the analysis of water quality and body fluids by virtue of the unique advantages of easy operation and rapid response. However, the potential drift during the long-term stability test hinders their further practical applications. Designing novel redox SC layers with large capacitance and high hydrophobicity is a promising approach to stabilize the potential stability, meanwhile, exploring the transduction mechanism is also of great guiding significance for the precise design of SC layer materials. Herein, flower-like copper sulfide (CunS-50) composed of nanosheets is meticulously designed as the redox SC layer by modification with the surfactant (CTAB). The CunS-50-based Ca2+-ISE (CunS-50/Ca2+-ISE) demonstrates a near-Nernstian slope of 28.23 mV/dec for Ca2+ in a wide activity linear range of 10-7 to 10-1 M, with a low detection limit of 3.16 × 10-8 M. CunS-50/Ca2+-ISE possesses an extremely low potential drift of only 1.23 ± 0.13 µV/h in the long-term potential stability test. Notably, X-ray absorption fine-structure (XAFS) spectra and electrochemical experiments are adopted to elucidate the transduction mechanism that the lipophilic anion (TFPB-) participates in the redox reaction of CunS-50 at the solid-solid interface of ion-selective membrane (ISM) and redox inorganic SC layer (CunS-50), thereby promoting the generation of free electrons to accelerate ion-electron transduction. This work provides an in-depth comprehension of the transduction mechanism of the potentiometric response and an effective strategy for designing redox materials of ion-electron transduction triggered by lipophilic anions.

Practical Strategy for Arsenic(III) Electroanalysis without Modifier in Natural Water: Triggered by Iron Group Ions in Solution.

Significant progress has been made in nanomaterial-modified electrodes for highly efficient electroanalysis of arsenic(III) (As(III)). However, the modifiers prepared using some physical methods may easily fall off, and active sites are not uniform, causing the potential instability of the modified electrode. This work first reports a promising practical strategy without any modifiers via utilizing only soluble Fe3+ as a trigger to detect trace-level As(III) in natural water. This method reaches an actual detection limit of 1 ppb on bare glassy carbon electrodes and a sensitivity of 0.296 µA ppb-1 with excellent stability. Kinetic simulations and experimental evidence confirm the codeposition mechanism that Fe3+ is preferentially deposited as Fe0, which are active sites to adsorb As(III) and H+ on the electrode surface. This facilitates the formation of AsH3, which could further react with Fe2+ to produce more As0 and Fe0. Meanwhile, the produced Fe0 can also accelerate the efficient enrichment of As0. Remarkably, the proposed sensing mechanism is a general rule for the electroanalysis of As(III) that is triggered by iron group ions (Fe2+, Fe3+, Co2+, and Ni2+). The interference analysis of coexisting ions (Cu2+, Zn2+, Al3+, Hg2+, Cd2+, Pb2+, SO42-, NO3-, Cl-, and F-) indicates that only Cu2+, Pb2+, and F- showed inhibitory effects on As(III) due to the competition of active sites. Surprisingly, adding iron power effectively eliminates the interference of Cu2+ in natural water, achieving a higher sensitivity for 1-15 ppb As(III) (0.487 µA ppb-1). This study provides effective solutions to overcome the potential instability of modified electrodes and offers a practical sensing platform for analyzing other heavy-metal anions.

Generalizable Descriptors of Highly Sensitive Detection of As(III) over Transition-Metal Single Atoms: A Combined Density Function Theory and Gradient Boosting Regression Approach.

Traditional nanomodified electrodes have made great achievements in electrochemical stripping voltammetry of sensing materials for As(III) detection. Moreover, the intermediate states are complicated to probe because of the ultrashort lifetime and complex reaction conditions of the electron transfer process in electroanalysis, which seriously hinder the identification of the actual active site. Herein, the intrinsic interaction of highly sensitive analytical behavior of nanomaterials is elucidated from the perspective of electronic structure through density functional theory (DFT) and gradient boosting regression (GBR). It is revealed that the atomic radius, d-band center (εd), and the largest coordinative TM-N bond length play a crucial role in regulating the arsenic reduction reaction (ARR) performance by the established ARR process for 27 sets of transition-metal single atoms supported on N-doped graphene. Furthermore, the database composed of filtered intrinsic electronic structural properties and the calculated descriptors of the central metal atom in TM-N4-Gra were also successfully extended to oxygen evolution reaction (OER) systems, which effectively verified the reliability of the whole approach. Generally, a multistep workflow is developed through GBR models combined with DFT for valid screening of sensing materials, which will effectively upgrade the traditional trial-and-error mode for electrochemical interface designing.

Engineering Electron-Rich Sites on CoSe2-x Nanosheets for the Enhanced Electroanalysis of As(III): A Study on the Electronic Structure via X-ray Absorption Fine Structure Spectroscopy and Density Functional Theory Calculation.

Vacancy and doping engineering are promising pathways to improve the electrocatalytic ability of nanomaterials for detecting heavy metal ions. However, the effects of the electronic structure and the local coordination on the catalytic performance are still ambiguous. Herein, cubic selenium vacancy-rich CoSe2 (c-CoSe2-x) and P-doped orthorhombic CoSe2-x (o-CoSe2-x|P) were designed via vacancy and doping engineering. An o-CoSe2-x|P-modified glass carbon electrode (o-CoSe2-x|P/GCE) acquired a high sensitivity of 1.11 µA ppb-1 toward As(III), which is about 40 times higher than that of c-CoSe2-x, outperforming most of the reported nanomaterial-modified glass carbon electrodes. Besides, o-CoSe2-x|P/GCE displayed good selectivity toward As(III) compared with other divalent heavy metal cations, which also exhibited excellent stability, repeatability, and practicality. X-ray absorption fine structure spectroscopy and density functional theory calculation demonstrate that electrons transferred from Co and Se to P sites through Co-P and Se-P bonds in o-CoSe2-x|P. P sites obtained plentiful electrons to form active centers, which also had a strong orbital coupling with As(III). In the detection process, As(III) was bonded with P and reduced by the electron-rich sites in o-CoSe2-x|P, thus acquiring a reinforced electrochemical sensitivity. This work provides an in-depth understanding of the influence of the intrinsic physicochemical properties of sensitive materials on the behavior of electroanalysis, thus offering a direct guideline for creating active sites on sensing interfaces.

Sensing Material-Dependent Interference of Multiple Heavy Metal Ions: Experimental and Simulated Thermodynamics Study on Cu(II), Cd(II), and As(III) Electroanalysis.

Interference among multiple heavy metal ions (HMIs) is a significant problem that must be solved in electroanalysis, which extremely restricts the practical popularization of electrochemical sensors. However, due to the limited exploration of the intrinsic mechanism, it is still difficult to confirm the influencing factors. In this work, a series of experimental and theoretical electroanalysis models have been established to investigate the electroanalysis results of Cu(II), Cd(II), As(III), and their mixtures, which were based on the simple structure and stable coordination of nickel single-atom catalysts. X-ray absorption spectroscopy and density functional theory calculations were used to reveal the underlying detection mechanism of the 50-fold boosting effect of Cu(II) on As(III) while Cd(II) inhibits As(III). Combining the application of the thermodynamic model and Fourier transform infrared reflection, the specific interaction of the nanomaterials and HMIs on the interface is considered to be the fundamental source of the interference. This work opens up a new way of thinking about utilizing the unique modes of interplay between nanomaterials and HMIs to achieve anti-interference intelligent electrodes in stripping analysis.

Transplantation of Human Neural Stem Cells in a Parkinsonian Model Exerts Neuroprotection via Regulation of the Host Microenvironment.

Parkinson's disease (PD) is characterized by a progressive loss of dopaminergic neurons and consequent dopamine (DA) deficit, and current treatment still remains a challenge. Although neural stem cells (NSCs) have been evaluated as appealing graft sources, mechanisms underlying the beneficial phenomena are not well understood. Here, we investigate whether human NSCs (hNSCs) transplantation could provide neuroprotection against DA depletion by recruiting endogenous cells to establish a favorable niche. Adult mice subjected to 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) were transplanted with hNSCs or vehicle into the striatum. Behavioral and histological analyses demonstrated significant neurorescue response observed in hNSCs-treated animals compared with the control mice. In transplanted animals, grafted cells survived, proliferated, and migrated within the astrocytic scaffold. Notably, more local astrocytes underwent de-differentiation, acquiring the properties of NSCs or neural precursor cells (NPCs) in mice given hNSCs. Additionally, we also detected significantly higher expression of host-derived growth factors in hNSCs-transplanted mice compared with the control animals, together with inhibition of local microglia and proinflammatory cytokines. Overall, our results indicate that hNSCs transplantation exerts neuroprotection in MPTP-insulted mice via regulating the host niche. Harnessing synergistic interaction between the grafts and host cells may help optimize cell-based therapies for PD.

Transforming crystal structures of cobalt molybdate to generate electron-rich sites for electrochemical detection of Pb(II).

BACKGROUND: Most of the investigations on distinct crystal structures of catalysts are individually focused on the difference of surface functional groups or adsorption properties, but rarely explore the changes of active sites to affect the electrocatalytic performance. Catalysts with diverse crystal structures had been applied to modified electrodes in different electrocatalytic reactions. However, there is currently a lack of an essential understanding for the role of real active sites in catalysts with crystalline structures in electroanalysis, which is crucial for designing highly sensitive sensing interfaces. RESULTS: Herein, cobalt molybdate with divergent crystal structures (α-CoMoO4 and ß-CoMoO4) were synthesized by adjusting the calcination temperature, indicating that α-CoMoO4 (800 °C) (60.00 µA µM-1) had the highest catalytic ability than ß-CoMoO4 (700 °C) (38.68 µA µM-1) and α-CoMoO4 (900 °C) (29.55 µA µM-1) for the catalysis of Pb(II). It was proved that the proportion of Co(II) and Mo(IV) as electron-rich sites in α-CoMoO4 (800 °C) were higher than ß-CoMoO4 (700 °C) and α-CoMoO4 (900 °C), possessing more electrons to participate in the valence cycles of Co(II)/Co(III) and Mo(IV)/Mo(VI) to boost the catalytic reduction of Pb(II). Specifically, Co(II) transferred a part of electrons to Mo(VI), promoting the formation of Mo(IV). Co(II) and Mo(IV), as the electron-rich sites, providing electrons to Pb(II), further accelerating the conversion of Pb(II) into Pb(0). SIGNIFICANCE: In the process of detecting Pb(II), the CoMoO4 structures under different temperatures have distinct content of electron-rich sites Co(II) and Mo(IV). α-CoMoO4 (800 °C), with the highest content are benefited to detect Pb(II). This work is conducive to understanding the effect of the changes of active sites resulting from crystal transformation on the electrocatalytic performance, and provides a way to construct sensitive electrochemical interfaces of distinct active sites.

Multi-dimensional signals coupling of simultaneous acquisition stripping current with laser-induced breakdown spectroscopy for accurate analysis of Cd(II) in coexisting Cu(II).

BACKGROUND: Despite significant advancements in detecting Cd(II) using nanomaterials-modified sensitive interfaces, most detection methods rely solely on a single electrochemical stripping current to indicate concentration. This approach often overlooks potential inaccuracies caused by interference from coexisting ions. Therefore, establishing multi-dimensional signals that accurately reflect Cd(II) concentration in solution is crucial. RESULTS: In this study, we developed a system integrating concentration, electrochemical stripping current, and laser-induced breakdown spectroscopy (LIBS) characteristic peak intensity through in-situ laser-induced breakdown spectroscopy and electrochemical integrated devices. By simultaneously acquiring multi-dimensional signals to dynamically track the electrochemical deposition and stripping processes, we observed that replacement reactions occur between Cu(II) and Cd(II) on the surface of Ru-doped MoS2 modified carbon paper electrodes (Ru-MoS2/CP). These reactions facilitate the oxidation of Cd(0) to Cd(II) during the stripping process, significantly increasing the currents of Cd(II). Remarkably, the ingenious design of the Ru-MoS2 sensitive interface allowed for the undisturbed deposition of Cu(II) and Cd(II) during the electrochemical deposition process. Consequently, our in-situ integrated device achieved accurate detection of Cd(II) in complex environments, boasting a detection sensitivity of 8606.5 counts µM⁻1. SIGNIFICANCE: By coupling multi-dimensional signals from stripping current and LIBS spectra, we revealed the interference process between Cu(II) and Cd(II), providing valuable insights for accurate electrochemical analysis of heavy metal ions in complex water environments.

Modulating paired Ir-O-Ir via electronic perturbations of correlated Ir single atoms to overcome catalytic selectivity.

Single-atom catalysts have been extensively utilized for electrocatalysis, in which electronic metal-support interactions are typically employed to stabilize single atoms. However, this neglects the metal-metal interactions of adjacent atoms, which are essential for the fine-tuning of selective sites. Herein, the high-loading of Ir single atoms (Ir SAs) (8.9 wt%) were adjacently accommodated into oxygen vacancy-rich Co3O4 nanosheets (Ir SAs/Co3O4). Electronic perturbations for both Ir single atoms and Co3O4 supports were observed under electronic metal-support and metal-metal interactions, thus generating Ir-O-Co/Ir units. Electrons were transferred from Co and Ir to O atoms, inducing the depletion of 3d/5d states in Co/Ir and the occupation of 2p states in O atoms to stabilize the Ir SAs. Moreover, the O atoms of Ir-O-Ir functioned as the main active sites for the electrocatalysis of As(iii), which reduced the energy barrier for the rate-determining step. This was due to the stronger electronic affinities for intermediates from reduction of As(iii), which were completely distinct from other coordinated O atoms of Co3O4 or IrO2. Consequently, the resultant Ir SAs/Co3O4 exhibited far more robust electrocatalytic activities than IrO2/Co3O4 and Co3O4 in the electrocatalysis of As(iii). Moreover, there was a strong orbital coupling effect between the coordinated O atoms of Ir SAs and the -OH of H3AsO3, thus exhibiting superior selectivity for As(iii) in contrast to other common heavy metal cations. This work offers useful insights into the rational design of intriguing SACs with high selectivity and stability for the electrocatalysis and electrochemical analysis of pollutants on an electronic level.

A Ferritin-Albumin-Cu Nanoparticle that Efficaciously Delivers Copper(II) Ions to a Tumor and Improves the Therapeutic Efficacy of Disulfiram.

The application of disulfiram can be traced back to the 1920s, from when it was utilized to facilitate alcohol abstinence by producing allergic reactions toward alcohol. In previous research, combination of disulfiram and copper ions has demonstrated significant anti-tumor activity. However, both disulfiram and copper ions lack the ability of specific targeting to tumor tissues and may lead to a high risk of side effects, especially for copper ion, which is a kind of toxic heavy metal. Herein, a ferritin-albumin-Cu nanoparticle (FHC NP) was introduced. The nanoparticle was synthesized by first covalently cross-linking ferritin and albumin and then encapsulating the copper ions in the ferritin nanocage. The nanoparticle showed good accumulation in a tumor and when combined with disulfiram exhibited good in vitro selectivity toward cancer cells and better in vivo anti-tumor activity. Herein, the nanoparticle invented here represented a good strategy to efficaciously deliver copper ions into tumors and thus improve the therapeutic efficacy of disulfiram in tumor therapy.

Enhancing the Effect of Pharmacological Ascorbate in Cancer Therapy via Acid-Triggered Ferritin Nanoparticles.

The application of ascorbate (vitamin C) for cancer therapy was first proposed in the 1970s and has shown promising results in recent clinical trials. Pharmacological doses of ascorbate selectively induce cell death in different types of cancer cells through the generation of H2 O2. However, some cancer cells are resistant to ascorbate. So increasing the sensitivity of resistant cancer cells to ascorbate has attracted considerable attention. Till now, a few attempts in nanomaterials have been made to improve the effect of ascorbate. In this study, a simple ferritin caged copper nanoparticle (Fn-Cu) significantly improves the susceptibility of ascorbate-resistant cancer cells to pharmacological ascorbate via selective inhibition of catalase activity in cancer cells, while having negligible cytotoxicity to normal cells. Remarkably, combination of Fn-Cu with a lower dose of ascorbate significantly inhibits ascorbate-resistant tumor growth and metastasis in vivo. These data demonstrate Fn-Cu has the therapeutic potential by enhancing the effect of ascorbate in cancer therapy.

Value of intra-operative Doppler sonographic measurements in predicting post-operative anastomotic leakage in rectal cancer: a prospective pilot study.

BACKGROUND: Anastomotic leakage is a serious surgical complication in rectal cancer; however, effective evaluation methods for predicting anastomotic leakage individual risk in patients are not currently available. This study aimed to develop a method to evaluate the risk of leakage during surgery. METHODS: The 163 patients with rectal cancer, who had undergone anterior resection and low-ligation procedures for Doppler sonographic hemodynamic measurement from April 2011 to January 2015 in Peking University Cancer Hospital, were prospectively recruited. A predictive model was constructed based on the associations between anastomotic leakage and alterations in the anastomotic blood supply in the patients, using both univariate and multivariate statistical analyses, as well as diagnostic methodology evaluation, including Chi-square test, logistic regression model, and receiver operating characteristic curve. RESULTS: The overall anastomotic leakage incidence was 9.2% (15/163). Doppler hemodynamic parameters whose reduction was significantly associated with anastomotic leakage were peak systolic velocity, pulsatility index, and resistance index. The areas under the receiver operating characteristic curve of residual rates of peak systolic velocity, pulsatility index, and resistance index in predicting anastomotic leakage were 0.703 (95% confidence interval [CI]: 0.552-0.854), 0.729 (95% CI: 0.579-0.879), and 0.689 (95% CI: 0.522-0.856), respectively. The predictive model revealed that the patients with severely reduced blood-flow signal exhibited a significantly higher incidence rate of anastomotic leakage than those with sufficient blood supply (19.6% vs. 3.7%, P = 0.003), particularly the patients with low rectal cancer (25.9% vs. 3.9%, P = 0.007) and those receiving neoadjuvant chemoradiotherapy (32.1% vs. 3.7%, P = 0.001), independent of prophylactic ileostoma. Multivariate analysis revealed that insufficient blood supply of the anastomotic bowel was an independent risk factor for anastomotic leakage (odds ratio: 10.37, 95% CI: 2.703-42.735, P = 0.001). CONCLUSION: Based on this explorative study, Doppler sonographic hemodynamic measurement of the anastomotic bowel presented potential value in predicting anastomotic leakage.

Analysis of volatile components in a Chinese fish sauce, Fuzhou Yulu, by gas chromatography-mass spectrometry.

Volatile components of Fuzhou Yulu, a Chinese fish sauce, were analyzed by gas chromatography-mass spectrometry (GC-MS), and two pretreatment methods, i.e., purge and trap (P&T) GC-MS and ethyl acetate extraction followed by GC-MS, were compared. P&T-GC-MS method determined 12 components, including sulfur-containing constituents (such as dimethyl disulfide), nitrogen-containing constituents (such as pyrazine derivatives), aldehydes and ketones. Ethyl acetate extraction followed by GC-MS method detected 10 components, which were mainly volatile organic acids (such as benzenepropanoic acid) and esters. Neither of the two methods detected alcohols or trimethylamine. This study offers an important reference to determine volatile flavor components of traditional fish sauce through modern analysis methods.

Optimization of acidic extraction of astaxanthin from Phaffia rhodozyma.

Optimization of a process for extracting astaxanthin from Phaffia rhodozyma by acidic method was investigated, regarding several extraction factors such as acids, organic solvents, temperature and time. Fractional factorial design, central composite design and response surface methodology were used to derive a statistically optimal model, which corresponded to the following optimal condition: concentration of lactic acid at 5.55 mol/L, ratio of ethanol to yeast dry weight at 20.25 ml/g, temperature for cell-disruption at 30 degrees C, and extraction time for 3 min. Under this condition, astaxanthin and the total carotenoids could be extracted in amounts of 1294.7 microg/g and 1516.0 microg/g, respectively. This acidic method has advantages such as high extraction efficiency, low chemical toxicity and no special requirement of instruments. Therefore, it might be a more feasible and practical method for industrial practice.

A case of subdural hematoma with a medical history of hemophilia a and a review of related literature.

BACKGROUND: Intracranial hemorrhage is the most common emergency in the neurology department, and patients with a medical history of hemophilia have a risk of severe bleeding. CASE PRESENTATION: A 56-year-old man was admitted to the emergency department in our hospital. He was diagnosed with hemophilia A and subdural hematoma. We administered an infusion of factor VIII to decrease the risk of bleeding and improve the prognosis. Factor VIII infusion is the most important factor in treating hemophilia A patients. CONCLUSION: We recommend carefully checking coagulation function and the medical history once these patients are admitted, especially in the emergency department.

Water accelerated transformation of d-limonene induced by ultraviolet irradiation and air exposure.

d-Limonene is a fragrant chemical that widely exists in aromatic products. Isotopic labelling of water molecules plus GC-MS and GC-PCI-Q-TOF analyses were used to investigate the influence of water molecules on chemical transformation of d-limonene induced by UV irradiation and air exposure. The results showed that the synergistic effect of UV irradiation, air exposure and water presence could facilitate d-limonene transformation into the limonene oxides: p-mentha-2,8-dienols, hydroperoxides, carveols, l-carvone and carvone oxide. UV irradiation, air exposure, or water alone, however, caused negligible d-limonene transformation. With the aid of isotopic labelling of water and oxygen molecules, it was found that water molecules were split into hydrogen radicals and hydroxyl radicals, and the hydrogen radicals, in particular, promoted the transformation reactions. This study has elucidated the mechanism and factors that influence the transformation of d-limonene, which will benefit industries involved in production and storage of d-limonene-containing products.

Studies on optimization of nitrogen sources for astaxanthin production by Phaffia rhodozyma.

Fermentation of Phaffia rhodozyma is a major method for producing astaxanthin, an important pigment with industrial and pharmaceutical application. To improve astaxanthin productivity, single factor and mixture design experiments were used to investigate the effects of nitrogen source on Phaffia rhodozyma cultivation and astaxanthin production. Results of single factor experiments showed nitrogen source could significantly affect P. rhodozyma cultivation with respect to carbon source utilization, yeast growth and astaxanthin accumulation. Further studies of mixture design experiments using (NH(4))(2)SO(4), KNO(3) and beef extract as nitrogen sources indicated that the proportion of three nitrogen sources was very important to astaxanthin production. Validation experiments showed that the optimal nitrogen source was composed of 0.28 g/L (NH(4))(2)SO(4), 0.49 g/L KNO(3) and 1.19 g/L beef extract. The kinetic characteristics of batch cultivation were investigated in a 5-L pH-stat fermentor. The maximum amount of biomass and highest astaxanthin yield in terms of volume and in terms of biomass were 7.71 mg/L and 1.00 mg/g, respectively.

Recovery and purification of limonin from pummelo [Citrus grandis] peel using water extraction, ammonium sulfate precipitation and resin adsorption.

Limonin is a bioactive compound that is traditionally extracted from citrus seeds using organic solvents or alkaline/metal ion solutions. In the present study, pummelo [Citrus grandis] peel was investigated for limonin preparation using a novel process consisting of water extraction, ammonium sulfate precipitation and resin adsorption. The pummelo peel was determined to have 4.7mg/g limonin, which could be extracted by water and further recovered by ammonium sulfate precipitation with a yield of 2.4mg/g, which was similar to that of traditional process using ethanol extraction and vacuumed evaporation. The precipitated limonin was purified by resin adsorption and crystallization with a purity of 96.4%. In addition, the limonin was identified via the analyses of retention time, infrared spectrum and nuclear magnetic resonance. This study indicates a novel and eco-friendly process for recovering limonin, providing a new candidate for limonin preparation.

Characterization of the Aldehydes and Their Transformations Induced by UV Irradiation and Air Exposure of White Guanxi Honey Pummelo (Citrus Grandis (L.) Osbeck) Essential Oil.

Aldehydes are key aroma contributors of citrus essential oils. White Guanxi honey pummelo essential oil (WPEO) was investigated in its aldehyde constituents and their transformations induced by UV irradiation and air exposure by GC-MS, GC-O, and sensory evaluation. Nine aldehydes, i.e., octanal, nonanal, citronellal, decanal, trans-citral, cis-citral, perilla aldehyde, dodecanal, and dodecenal, were detected in WPEO. After treatment, the content of citronellal increased, but the concentrations of other aldehydes decreased. The aliphatic aldehydes were transformed to organic acids. Citral was transformed to neric acid, geranic acid, and cyclocitral. Aldehyde transformation caused a remarkable decrease in the minty, herbaceous, and lemon notes of WPEO. In fresh WPEO, ß-myrcene, d-limonene, octanal, decanal, cis-citral, trans-citral, and dodecenal had the highest odor dilution folds. After the treatment, the dilution folds of decanal, cis-citral, trans-citral, and dodecenal decreased dramatically. This result provides information for the production and storage of aldehyde-containing products.