Visible-Light-Initiated Multicomponent Reactions of α-Diazoesters to Access Organophosphorus Compounds.

A simple visible-light-initiated strategy has been established for the construction of organophosphorus compounds via aerobic multicomponent reaction of α-diazoesters, cyclic ethers, and P(O)H compounds under air. A number of phosphonates and phosphinates could be efficiently isolated in moderate to good yields without the use of photosensitizers and metal reagents. This multicomponent reaction has advantages of mild condition, simple operation, eco-friendly energy, good functional-group tolerance, and gram-scale synthesis.

Ratiometric fluorescence sensing of formaldehyde in food samples based on bifunctional MOF.

A new fluorescence strategy was described for ratiometric sensing of formaldehyde (FA) with bifunctional MOF, which acted as a fluorescence reporter as well as biomimetic peroxidase. With the assistance of H2O2, NH2-MIL-101 (Fe) catalyzes the oxidation of non-luminescent substrate o-phenylenediamine (OPD) to produce fluorescent product (oxOPD) with the maximum emission at 570 nm. Besides, intrinsic fluorescence of MOF (λem = 445 nm) was quenched by oxOPD through inner filter effect (IFE). However, FA and OPD reacted to generate Schiff bases, which competitively consumed OPD inhibiting the generation of oxOPD. Under the excitation wavelength of 375 nm, a ratiometric strategy was designed to detect FA with the fluorescence intensity ratio at 445 nm and 570 nm (F445/F570) as readout signal. This strategy exhibited a wide linear range (0.1-50 µM) and low detection limit of 0.03 µM. This method was confirmed for FA detection in food samples. In addition to establishing a new method to detect FA, this work will open new applications of MOF in food safety.

Carbon quantum dots-functionalized silica stationary phase for pharmaceutical analysis by a green liquid chromatography mode.

Facing the trends of green chemistry, this work tries to find a novel material for per aqueous liquid chromatography (PALC) aiming to reduce the consumption of hazardous reagents. As a kind of green nanomaterials, the chromatographic performance of carbon quantum dots (CQDs) in PALC was rarely studied. Here, hydrophilic CQDs were prepared by a simple hydrothermal method using citric acid and ethylenediamine as carbon sources. The synthesized CQDs with functional groups of amino, carboxyl, and hydroxyl were decorated on silica gels forming a novel Si-CQDs stationary phase. This Si-CQDs column possesses the typical retention feature of PALC. Compounds with different polarities including hydrophobic pesticides, polar sulfonamides, ß-adrenoceptor blockers and agonists, as well as hydrophilic nucleosides and bases obtained satisfactory separation on this Si-CQDs column under PALC mode, even better resolution than in hydrophilic interaction liquid chromatography (HILIC) mode. A mixture of four sulfonamides can be separated within 6 min using a mobile phase containing only 5% acetonitrile, and the resolution achieves 2.39, 2.13, and 1.83 with an average column efficiency of 1400. For certain compounds, this Si-CQDs column showed better separation performance than commercial SiO2 column, NH2 column, and C18 column. The retention mechanism includes hydrophobic and electrostatic interactions due to the multifunctional groups of CQDs. This Si-CQDs column achieved the rapid detection of residual sulfonamides in milk with simplified sample pretreatment process and the detection of atenolol in commercial atenolol tablets. The developed Si-CQDs column has great prospects in low-cost and environmentally friendly separation and analysis.

Lead halide perovskites with aggregation-induced emission feature coupled with gold nanoparticles for fluorescence detection of heparin.

Herein, a new kind of lead halide perovskite (LHP, (C12H25NH3)2PbI4) with aggregation-induced emission (AIE) feature is developed as a fluorescent probe for heparin (Hep). The LHPs exhibit high emission when they aggregate in water. Interestingly, a few picomoles of dispersed gold nanoparticles (AuNPs) can quench the emission of LHPs, but the aggregated AuNPs are invalid. When protamine (Pro) is mixed with AuNPs at first, the negatively charged AuNPs aggregate through electrostatic interaction, producing the AIE recovery. Nevertheless, Hep disturbs the interaction between AuNPs and Pro due to its strong electrostatic interaction with Pro. Therefore, the dispersed AuNPs quench the fluorescence of LHPs again. A response linear range of Hep of 0.8-4.2 ng ml-1is obtained, and the detection limit is 0.29 ng ml-1. Compared with other probes for determination of Hep with AuNPs, this strategy exhibits better sensitivity due to the small quantity of AuNPs used. Finally, it is also successfully applied to detect Hep in human serum samples with satisfactory recoveries.

MOF@MnO2nanocomposites prepared usingin situmethod and recyclable cholesterol oxidase-inorganic hybrid nanoflowers for cholesterol determination.

In this work, through thein situgrowth of MnO2nanosheets on the surface of terbium metal-organic frameworks (Tb-MOFs), MOF@MnO2nanocomposites are prepared and the fluorescence of Tb-MOFs is quenched significantly by MnO2. Additionally, the hybrid nanoflowers are self-assembled by cholesterol oxidase (ChOx) and copper phosphate (Cu3(PO4)2·3H2O). Then a new strategy for cholesterol determination is developed based on MOF@MnO2nanocomposites and hybrid nanoflowers. Cholesterol is oxidized under the catalysis of hybrid nanoflowers to yield H2O2, which further reduces MnO2nanosheets into Mn2+. Hence, the fluorescence recovery of Tb-MOFs is positively correlated to the concentration of cholesterol in the range of 10 to 360µM. The limit of detection (LOD) of cholesterol is 1.57µM. On the other hand, the hierarchical and confined structure of ChOx-inorganic hybrid nanoflowers greatly improve the stability of the enzyme. The activity of hybrid nanoflowers remains at a high level for one week when stored at room temperature. Moreover, the hybrid nanoflowers can be collected by centrifugation and reused. The activity of hybrid nanoflowers can continue at a high level for five cycles of determination. Therefore, it can be concluded that the hybrid nanoflowers are more stable and more economic than free enzymes, and they show a similar sensitivity and specificity to cholesterol compared with free ChOx. Finally, this strategy has been further validated for the determination of cholesterol in serum samples with satisfactory recoveries.

A fluorescence strategy for monitoring α-glucosidase activity and screening its inhibitors from Chinese herbal medicines based on Cu nanoclusters with aggregation-induced emission.

Herein, the self-assembly of 1-dodecanethiol-capped Cu nanoclusters (DT-Cu NCs) is obtained by annealing of dibenzyl ether solution of nanoclusters. These aggregates are composed of small clusters and emit a high level of aggregation-induced emission (AIE) in water. Based on the quenching effect of 4-nitrophenol (4-NP) on DT-Cu NCs, a fluorescence strategy is developed to monitor α-glucosidase (α-Glu) activity and screen its inhibitors from Chinese herbal medicines. 4-Nitrophenyl-α-D-glucopyranoside (NGP) is selected as the substrate, which is further hydrolyzed to yield 4-NP through the catalysis of α-Glu. The quenching efficiency is positively correlated to the concentration of α-Glu. Furthermore, the inhibitory effects of the extracts from four Chinese herbal medicines (i.e., the rind of Punica granatum L., Momordica grosvenorii Swingle., Crataegus pinnatifida Bge., and Lycium barbarum L.) on the α-Glu activity have been studied. The IC50 values of extracts from the rind of Punica granatum L. and Momordica grosvenorii Swingle are 0.23 and 0.37 g/L, respectively, so they show obvious inhibitory effects on α-Glu. The extracts of Crataegus pinnatifida Bge. and Lycium barbarum L. exhibit relatively weak inhibitory effects. Hence, the proposed strategy can be applicable for screening α-Glu inhibitors from Chinese herbal medicines. Last but not the least, by immobilizing DT-Cu NCs into agarose hydrogels in polyethylene tubes, a visual device is fabricated to screen α-Glu inhibitors with high throughput and sensitivity.

pH-modulated aggregation-induced emission of Au/Cu nanoclusters and its application to the determination of urea and dissolved ammonia.

A fluorescence platform is designed based on aggregation-induced emission of Au/Cu nanoclusters (Au/Cu NCs) driven by pH value. When pH increases from 6.0 to 7.0, Au/Cu NCs change from aggregation to dispersion, accompanied by the oxidation of Cu cores. Under the catalysis of urease, urea is hydrolysed to release ammonia, which further undergoes a hydrolysis reaction to produce OH-, causing the pH to increase. The fluorescence of Au/Cu NCs quenches linearly at 590 nm with the excitation wavelength at 320 nm when the concentration of urea varies from 5.0 to 100 µM. The limit of detection (LOD) and limit of quantification (LOQ) of urea are 2.23 and 7.45 µM, respectively. Combined with headspace single-drop microextraction technology, Au/Cu NCs are employed to monitor dissolved ammonia with low-cost and simple operation. The linear range of dissolved ammonia is from 20 to 300 µM. The LOD and LOQ of dissolved ammonia are 7.04 and 23.4 µM, respectively. The relative standard deviation (RSD) values of the intra-day and inter-day precision of urea are 2.4-3.0% and 3.0-3.7%, respectively, and those of dissolved ammonia are in the range 3.4-5.1% (intra-day precision) and 4.2-5.8% (inter-day precision). No interferences have been indentified in the determination of urea and dissolved ammonia. Finally, the proposed method has been applied to determine urea in human urine samples and dissolved ammonia in water samples with satisfactory results.Graphical abstract The pH increase produces the dispersion and decomposition of Au/Cu NCs, leading to the fluorescence quenching. Both urea and dissolved ammonia are detected successfully because they cause the pH change to alkaline.

Recent progresses of derivatization approaches in the targeted lipidomics analysis by mass spectrometry.

Lipidomics plays an essential role in the development of an improved understanding of lipids metabolism and the identification of new biomarkers or therapeutic targets of related diseases. The strong analytical power of mass spectrometry and its rapid developments in the respect of instruments and techniques have significantly accelerated the emerging lipidomics and related application fields in biology, medicine, and pharmacy. The strategy of chemical derivatization can remarkably improve the shortcomings of mass spectrometric analytical technologies of shotgun lipidomics and liquid chromatography mass spectrometry, and in the past decade many related studies have been reported for fatty acids, glycerophospholipids, sphingomyelins, monoglycerides, diacylglycerols, long-chain bases, steroids, and so on. Therefore, this review will focus on new chemical derivatization approaches about the research progresses of shotgun-based and liquid chromatography mass spectrometry-based targeted lipidomics (from 2005 to July 2019, most of reports emerged in the past 5 years), and put forward the problems and prospects in this field. It is expected to be helpful for the design and synthesis of new derivatization reagents, especially the outstanding stable isotope labeling derivatization reagents, and the development and application of new chemical derivatization strategies and matched mass spectrometric analysis methods.

Multiplexed derivatization strategy-based dummy molecularly imprinted polymers as sorbents for magnetic dispersive solid phase extraction of globotriaosylsphingosine prior to UHPLC-MS/MS quantitation.

A new series of 9-plex chemical isotope-labeling reagents, levofloxacin-based mass tags (LMTs) named as LMT359, 360, 361, 362, 363, 373, 375, 376, and 378, was firstly designed and synthesized for the high-throughput labeling of globotriaosylsphingosine (lyso-Gb3), a disease biomarker of Fabry disease. Creatively based on derivatization strategy-dummy template technique, dummy magnetic molecularly imprinted polymers (DMMIPs) were designed and prepared using LMT387-labeled lyso-Gb3 as a dummy template. The novel DMMIP material was used as sorbents for magnetic dispersive solid-phase extraction of 9-plexed LMT derivatives of lyso-Gb3 from equally mixed derivatization solutions. The enriched 8-plexed lyso-Gb3 derivatives from 8 real samples were quantified by ultra-high-performance liquid chromatography tandem mass spectrometry in a single run using simultaneously extracted LMT359-labeled standard lyso-Gb3 as internal standards. DMMIPs were characterized by using the transmission electron microscope (TEM), Fourier transform infrared, X-ray photoelectron spectroscopy, and some other characterization techniques. TEM micrograph showed that the prepared DMMIPs had an apparent imprinting layer. Triple-recognition abilities of DMMIPs towards LMT-lyso-Gb3 mainly rely on the hydrogen bonding, electrostatic attraction, hydrophobic interaction, and boronate affinity. The imprinting factor of DMMIPs towards LMT-lyso-Gb3 was 5.1. This method shows the advantages of high selectivity (triple recognition), high sensitivity, high accuracy (recovery 93.5-108.8%), and high throughput (8 samples in a single run). The proposed method was successfully applied to the determination of lyso-Gb3 in plasma samples with spiked recoveries in the range of 95.0-102.4%. This indicates that the method is promising in bioanalysis and medical testing of lyso-Gb3 in the future. Graphical abstract Synthesis of multiplexed derivatization reagents and its correlative molecularly imprinted polymers for magnetic extraction of globotriaosylsphingosine.

Colorimetric determination of the activities of tyrosinase and catalase via substrate-triggered decomposition of MnO2 nanosheets.

The authors describe novel colorimetric assays for tyrosinase (TYR) and catalase (CAT) based on the substrate-triggered decomposition of MnO2 nanosheets (NSs). The MnO2 NSs can act as oxidase mimics that catalyze the oxidation of the substrate tetramethylbenzidine (TMB) to form a blue dye with an absorption maximum at 652 nm. The oxidase-mimicking activity of the MnO2 NSs is inhibited by dopamine (DA)/hydrogen peroxide (H2O2) due to their decomposition of the MnO2 NSs. TYR catalyzes the oxidation of DA while CAT can decompose H2O2 into water and oxygen. Therefore, the oxidase-mimicking activity of MnO2 NSs is restored in the presence of both enzymes and their substrates. Based on the competitive consumption of substrates between enzymes and MnO2 NSs, a colorimetric method for determination of enzyme activity and its substrate is developed. The detection limits for TYR and CAT are 6 mU·mL-1 and 33 mU·mL-1, respectively. Graphical abstractA colorimetric method for monitoring enzyme activity and its substrate is described. It is based on the substrate-inhibited oxidase-mimicking activity of MnO2 nanosheets.

Molecular beacon-templated silver nanoclusters as a fluorescent probe for determination of bleomycin via DNA scission.

The authors describe a molecular beacon-based fluorescent probe for the determination of the cancer drug bleomycin (BLM). The probe was tagged with DNA-templated silver nanoclusters (DNA-AgNCs) and guanine-rich sequences (GRSs) at two terminals serving as signal reporter with a loop. In the absence of the BLM-iron(II) complex [BLM-Fe(II)], the probe has a hairpin shape and displays strong fluorescence because the AgNCs are close to the GRSs. In the presence of the BLM-Fe(II) complex, it will selectively cleave the probe at the 5'-GC-3' scission site of the loop. This displaces the AgNCs away from the GRSs and causes a decrease in fluorescence, best measured at excitation/emission wavelengths of 565/623 nm. This effect enables BLM to be detected with a detection limit as low as 33 pM, which was 1-3 orders of magnitude more sensitive than most of the previous reports. The probe was applied for the determination of BLM in spiked human serum samples, and excellent performance was achieved. In our perception, the method described here represents a promising tool for highly sensitive and specific analysis of BLM during cancer treatment. Graphical abstract Schematic of a highly sensitive fluorometric assay forbleomycin. It is based on molecular beacon-templated silver nanoclusters and DNA scission.

Wide-Acidity-Range pH Fluorescence Probes for Evaluation of Acidification in Mitochondria and Digestive Tract Mucosa.

The cells control their pH change in a very accurate range. pH plays important roles in cell autophagy and apoptosis. Previous evidence implies that the internal milieu of a tumor is acidified. Although the acidification in cells is investigated, the biological effects from multiple stimulating factors under the complex intracellular environment have not been thoroughly elaborated yet. Currently, there are few pH probes that perform in a wide acidity range, and a probe that is capable of measuring a wide pH range needs to be developed. Herein, we report two new fluorescent probes (BHNBD and CM-BHNBD) for the detection of mitochondrial and intramucosal acidification. The two probes respond to pH via an H+-driven TICT (twist intramolecular charge transfer) mechanism, and they can linearly report pH within a wide pH range: 7.00-2.00 following ∼148-fold fluorescence increase. The two probes also possess excellent membrane permeability, good photostability, and negligible cytotoxicity. The probes are successfully applied for quantifying the acidification in HeLa cells under the simultaneous stimulation of nutrient deprivation and oxidative stress. Our results demonstrate that the mitochondrial pH is in a dynamic fluctuating state during the acidification process, which suggests a potential cross-talk effect between cell autophagy and apoptosis. We also use the probes for quantifying the intramucosal pH variation in stomach and esophagus via manipulating cellular proton pump. The development of our probes is potentially expected to be used to monitor the intracellular/intramucosal acidification for biomedical research.

Rapid and sensitive determination of multiple endocrine-disrupting chemicals by ultrasound-assisted in situ derivatization dispersive liquid-liquid microextraction coupled with ultra-high-performance liquid chromatography/tandem mass spectrometry.

RATIONALE: Endocrine-disrupting chemicals (EDCs) in environment samples and food stuffs are an increasing serious public health issue due to their potency to interfere and deregulate several aspects of the endocrine system. Because of their extremely low abundance, it remains a challenging task to develop a sensitive detection method. METHODS: 4'-Carbonyl chloride rosamine (CCR) was used as a derivatization reagent for EDCs for the first time. A new ultrasound-assisted in situ derivatization/dispersive liquid-liquid microextraction (UA-DLLME with in situ derivatization) method for multiple EDCs including five estrogens, two alkylphenols, eight bisphenols, seven parabens and triclosan coupled with ultra-high-performance liquid chromatography/tandem mass spectrometry (UHPLC/MS/MS) has been developed and validated. RESULTS: The ionization efficiency of EDCs was greatly enhanced through the introduction of a permanent charged moiety of CCR into the derivatives during electrospray ionization (ESI)-MS analysis. The main variables potentially affecting the UA-DLLME with in situ derivatization process are optimized. The recoveries and matrix effects of 23 EDCs for the spiking samples were in the range of 83.0-116.0% and 85.8-114.6%, respectively. Good method reproducibility was achieved. CONCLUSIONS: The limits of detection (LODs) for 23 EDCs were 0.05-0.40 ng/L and 0.03-0.25 ng/g (dry weight, d.w.) for environment samples and food stuffs, respectively. The proposed method has been demonstrated to be suitable for simultaneous determination of multiple EDCs in real samples with high sensitivity, speediness, and good sample clean-up ability. Copyright © 2017 John Wiley & Sons, Ltd.

In situ quantification and evaluation of ClO-/H2S homeostasis in inflammatory gastric tissue by applying a rationally designed dual-response fluorescence probe featuring a novel H+-activated mechanism.

Homeostasis of ClO-/H2S plays a crucial role in the damage and repair of gastric tissue, but has rarely been investigated due to the challenge of in situ analysis in the highly acidic gastric environment. Herein, we designed a new H+-activated optical mechanism, involving controllable photoinduced electron transfer (PET) and switch of electron push-pull (SEPP), to develop the simple yet multifunctional probe (Z)-4-(2-benzylidenehydrazinyl)-7-nitrobenzo[c][1,2,5]oxadiazole (BNBD). First, the BNBD probe (Off) was protonated by the highly acidic media to trigger strong fluorescence (On). Then, the analytes ClO- and H2S reacted with the protonated BNBD, leading to ultrasensitive (ClO-: 2.7 nM and H2S: 6.9 nM) fluorescence quenching via the rapid oxidation of C[double bond, length as m-dash]N (50 s) and nitro reduction (10 s), respectively. With the logical discrimination by absorbance/colour (ClO-: 300 nm/colorless and H2S: 400 nm/orange), a strategy for the in situ quantification of ClO-/H2S in gastric mucosa and juice was developed. For the first time, the in situ quantitative monitoring of endogenous H2S and ClO-/H2S homeostasis as well as the pathologic manifestation in gastric mucosa were realized, thus overcoming the challenge of ClO-/H2S analysis under highly acidic conditions and enabling the in situ tissue quantification of ClO-/H2S. In combination with the assessment of mucosal damage, this study confirms the injurious/rehabilitative effects of ClO-/H2S on gastric mucosa (at 50-90 µm depth), which may facilitate the auxiliary diagnosis of stomach diseases induced by oxidative stress.

A versatile ratiometric nanosensing approach for sensitive and accurate detection of Hg2+ and biological thiols based on new fluorescent carbon quantum dots.

Herein, we first reported a facile synthesis method for fabrication of highly photoluminescent carbon quantum dots (CQDs) using sodium alginate as the carbon source and histidine as both the nitrogen source and functional monomer by one-pot hydrothermal synthesis. The as-prepared CQDs gave a high quantum yield of 32%. By employing the new CQDs and rhodamine B (RhB), we demonstrated a simple, facile, sensitive, and accurate ratiometric sensor for detection of Hg2+ and biological thiols. The photoluminescence of CQDs in the ratiometric sensor can be selectively and intensively suppressed by Hg2+ due to strong electrostatic interaction between the surface functional groups of the CQDs and Hg2+. When glutathione (GSH) was introduced into the "Turn Off" CQDs-RhB-Hg2+ sensing system, the fluorescence of the CQDs can be recovered rapidly due to the stronger affinity between thiol and Hg2+, while the fluorescence of the RhB remained constant in this sensing process. Based on the above principle, the ratiometric strategy for detecting Hg2+ and GSH can be achieved readily, and gives satisfactory limit of detections (LODs) of 30 and 20 nM for Hg2+ and GSH, respectively. The dual-emission fluorescent CQDs-RhB sensor does not need the complicated molecular design and the synthesis of dual-emission fluorophores. Meanwhile, the feasibility of the proposed method for analysis of water samples, food samples, and biological samples (plasma from mice oxidative stress study) was investigated. The developed ratiometric nanosensor is proven to be facile, with less sample consumption, rapid, lost cost, highly sensitive, and very selective for Hg2+ and biological thiol detection, which offers a new approach for environmental, food, and biological analysis. Graphical abstract Ratiometric nanosensing approach detection of Hg2+ and biological thiols.

Rapid and sensitive determination of phytosterols in functional foods and medicinal herbs by using UHPLC-MS/MS with microwave-assisted derivatization combined with dual ultrasound-assisted dispersive liquid-liquid microextraction.

In this work, a hyphenated technique of dual ultrasound-assisted dispersive liquid-liquid microextraction combined with microwave-assisted derivatization followed by ultra high performance liquid chromatography tandem mass spectrometry has been developed for the determination of phytosterols in functional foods and medicinal herbs. Multiple reaction monitoring mode was used for the tandem mass spectrometry detection. A mass spectrometry sensitive reagent, 4'-carboxy-substituted rosamine, has been used as the derivatization reagent for five phytosterols, and internal standard diosgenin was used for the first time. Parameters for the dual microextraction, microwave-assisted derivatization, and ultra high performance liquid chromatography tandem mass spectrometry were all optimized in detail. Satisfactory linearity, recovery, repeatability, accuracy and precision, absence of matrix effect, extremely low limits of detection (0.005-0.015 ng/mL) and limits of quantification (0.030-0.10 ng/mL) were achieved. The proposed method was compared with previously reported methods. It showed better sensitivity, selectivity, and accuracy. The matrix effect was also significantly reduced. The proposed method was successfully applied to the determination of five phytosterols in vegetable oil (sunflower oil, olive oil, corn oil, peanut oil), milk and orange juice (soymilk, peanut milk, orange juice), and medicinal herbs (Ginseng, Ganoderma lucidum, Cordyceps, Polygonum multiflorum) for the quality control of functional foods and medicinal herbs.

3-(2-Bromoacetamido)-N-(9-ethyl-9H)-carbazol fluorescent probe and its application for the determination of thiophenols in rubber products by HPLC with fluorescence detection and atmospheric chemical ionization mass spectrometry identification.

A rapid, sensitive, and selective precolumn derivatization method for the simultaneous determination of eight thiophenols using 3-(2-bromoacetamido)-N-(9-ethyl-9H)-carbazol as a labeling reagent by high-performance liquid chromatography with fluorescence detection has been developed. The labeling reagent reacted with thiophenols at 50°C for 50 min in aqueous acetonitrile in the presence of borate buffer (0.10 mol/L, pH 11.2) to give high yields of thiophenol derivatives. The derivatives were identified by online postcolumn mass spectrometry. The collision-induced dissociation spectra for thiophenol derivatives gave the corresponding specific fragment ions at m/z 251.3, 223.3, 210.9, 195.8, and 181.9. At the same time, derivatives exhibited intense fluorescence with an excitation maximum at λex = 276 nm and an emission maximum at λem = 385 nm. Excellent linear responses were observed for all analytes over the range of 0.033-6.66 µmol/L with correlation coefficients of more than 0.9997. Detection limits were in the range of 0.94-5.77 µg/L with relative standard deviations of less than 4.54%. The feasibility of derivatization allowed the development of a rapid and highly sensitive method for the quantitative analysis of trace levels of thiophenols from some rubber products. The average recoveries (n = 3) were in the range of 87.21-101.12%.

Development of a facile and sensitive HPLC-FLD method via fluorescence labeling for triterpenic acid bioavailability investigation.

Triterpenic acids are widely distributed in many fruits and are known for their medicinal benefits. The study of bioavailability has been an important task for a better understanding of the triterpenic acids. Although many methods based on fluorescence labeling for triterpenic acid determination have been established, these reported methods needed anhydrous conditions, which are not suitable for the convenient study of triterpenic acid bioavailability. Inspired by that, a versatile method, which overcomes the difficulty of the reported methods, has been first developed in this study. The novel method using 2-[12-benzo[b]acridin-5- (12H)-yl]-acetohydrazide (BAAH) as the fluorescence labeling reagent coupled with high-performance liquid chromatography with fluorescence detection was first developed for the study of triterpenic acid bioavailability. Furthermore, the labeling conditions have been optimized in order to achieve the best fluorescence labeling yield. Under the optimal conditions, the quantitative linear range of analytes was 2-1000 ng mL-1 , and the correlation coefficients were >0.9998. The detection limits for all triterpenic acid derivatives were achieved within the range of 0.28-0.29 ng mL-1 . The proposed method was successfully applied to the study of triterpenic acid bioavailability with excellent applicability and good reproducibility.

Sensitive determination of cholesterol and its metabolic steroid hormones by UHPLC-MS/MS via derivatization coupled with dual ultrasonic-assisted dispersive liquid-liquid microextraction.

RATIONALE: Quantitative analysis of cholesterol and its metabolic steroid hormones plays a vital role in diagnosing endocrine disorders and understanding disease progression, as well as in clinical medicine studies. Because of their extremely low abundance in body fluids, it remains a challenging task to develop a sensitive detection method. METHODS: A hyphenated technique of dual ultrasonic-assisted dispersive liquid-liquid microextraction (dual-UADLLME) coupled with microwave-assisted derivatization (MAD) was proposed for cleansing, enrichment and sensitivity enhancement. 4'-Carboxy-substituted rosamine (CSR) was synthesized and used as derivatization reagent. An ultra-high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) method was developed for determination of cholesterol and its metabolic steroid hormones in the multiple reaction monitoring mode. RESULTS: Parameters of dual-UADLLME, MAD and UHPLC-MS/MS were all optimized. Satisfactory linearity, recovery, repeatability, accuracy and precision, absence of matrix effect and extremely low limits of detection (LODs, 0.08-0.15 pg mL(-1) ) were achieved. CONCLUSIONS: Through the combination of dual-UADLLME and MAD, a determination method for cholesterol and its metabolic steroid hormones in human plasma, serum and urine samples was developed and validated with high sensitivity, selectivity, accuracy and perfect matrix effect results. Copyright © 2016 John Wiley & Sons, Ltd.

Rapid and sensitive screening of some acidic micronutrients in infant foods by HPLC with fluorescent detector.

BACKGROUND: Currently, commercially prepared complementary foods have become an important part of the diet of many infants and toddlers. But the method for simultaneous analysis of different types of micronutrient remains poorly investigated, which hinders the rapid and comprehensive quality control of infant foods. In the presented study, we first tried to employ the fluorescence labeling strategy combined with high-performance liquid chromatography-fluorescence detection for simultaneous determination of some acidic micronutrients including biotin, nicotinic acid, linolenic acid, eicosapentaenoic acid, docosahexaenoic acid, arachidonic acid and linoleic acid in infant foods. RESULTS: 2-(5-Benzoacridine) ethyl-p-toluenesulfonate was used as the fluorescence labeling reagent for simultaneous labeling of the seven components. The labeling conditions were optimized systematically by response surface methodology. The correlation coefficients for the calibration curves of the tested compounds ranged from 0.9991 to 0.9998. Limits of detection were in the range of 1.99-3.05 nmol L(-1) . Relative standard deviation values of retention time and peak area of seven compounds were less than 0.05% and 0.75%, respectively. The intra- and inter-day precision was in the range of 1.81-3.80% and 3.21-4.30%, respectively. When applied to analysis of several infant foods it showed good applicability. CONCLUSION: The developed method has been proven to be simple, inexpensive, selective, sensitive, accurate and reliable for analysis of some acidic micronutrients in infant foodstuffs. Furthermore, this developed method also has powerful potential in the analysis of many other complementary foodstuffs. © 2015 Society of Chemical Industry.