Scutellaria baicalensis Georgi is a well-known medical plant widely used as a famous traditional Chinese medicine. It has been reported that S. baicalensis can protect against oxidative stress and possess anti-inflammatory effect. In the present paper, an HPLC-diode array-chemiluminescence detection method for on-line detection was successfully developed to screen antioxidants in complex S. baicalensis extracts. Using the proposed approach, eight compounds in the S. baicalensis extracts were found to possess a potential antioxidant activity. Furthermore, the effects of purified compounds on protecting RAW 264.7 cells from hydrogen peroxide injury were also investigated in vitro to confirm the established method, which were consistent with the results of HPLC-diode array-chemiluminescence detection method. These results demonstrated that this method was a useful technique for rapidly screening and identifying bioactive components from complex herbal medicines.
Metal organic frameworks of type MOF-5 exhibit good adsorption capacity for many organic compounds. The authors have used nanoscale silica-coated zerovalent iron and MOF-5 to prepare, by co-precipitation, a novel magnetic nanomaterial of type Fe@MOF-5. Its morphology and structure were characterized by transmission electron microscopy and X-ray diffraction. The nanomaterial is shown to be well suited for magnetic solid phase extraction for five kinds of N- and S-containing polycyclic aromatic hydrocarbons prior to quantitation by HPLC. The limits of detection are in the 25 to 33 ng⋅L −1 concentration range. Four real water samples were used to validate the method, and the recoveries of spiked samples with concentrations of 5 and 10 ppb were found to be in the range between 92.6 and 97.3% ( n = 3). The Fe@MOF-5 sorbent obviously has excellent adsorption capability for such compounds, can be fairly easily synthesized, displays sensitivity, simplicity, ease of operation, and can be prepared at low costs. In our perception, it has a large potential in terms of monitoring such environmental pollutants.
A metal organic framework of type Fe@MOF-5 is found to exhibit good adsorption capacity for N- and S-containing polycyclic aromatic hydrocarbons. A sensitive magnetic solid phase extraction method with Fe@MOF-5 was developed for the determination of N- and S-containing polycyclic aromatic hydrocarbons from the water samples.
Polystyrene nanofibers were coated with copper nanoparticles (CuNPs) by a combination of electrospinning and in-situ reduction of Cu(II) using sodium borohydride as the reductant. The CuNPs on the nanofibers were characterized by energy dispersive spectrometry, scanning electron microscopy and transmission electron microscopy. A cartridge was packed with the nanofibers which then were activated with methanol and water. Glutathione (GSH) is found to quantitatively adsorbed by the packed cartridge at pH 3.0, and then can be desorbed with aqueous 2-mercaptoethanol and detected, after derivatization with ortho-phthalaldehyde, via high performance liquid chromatography with fluorometric detection. Under optimized conditions, the method has a 1.1 ng·mL −1 detection limit and a response that is linear in the 10–1000 ng·mL −1 GSH concentration range. The recoveries of GSH from artificial urine spiked at three levels (80, 400 and 800 ng·mL −1 ) are in the range of 94.6–98.6% with relative standard deviations (RSD) of <4.5% ( n = 5). The method was applied to assessing the differences in urinary GSH between high-risk infants and healthy infants. The results show that the levels of GSH of normal infants are significantly higher than those of high-risk infants ( P < 0.05).
Schematic of the preparation of CuNP-assembled nanofibers and the mechanism of extracting glutathione (GSH). GSH can be extracted by this material based on a strong interaction between the sorbent and GSH. This is attributed to the formation of Cu-S bonds between Cu and -SH.
Youyi Wu,Zhihao Gu,Wei Wei,Ruiming Xu,Yong Qian,Xuedong Wang
Herein, for the first time, a ternary natural deep eutectic solvent (NADES) was synthesized from nerol, menthol and formic acid, and was modulated by surfactant trioctylphosphine oxide (TOPO). A novel hollow fiber liquid–liquid–liquid microextraction method based on the NADES (SM-NADES-HF-LLLME) was proposed to enrich trace bisphenols (BPs) residues in water and subsequently detected by HPLC. The modulation of NADES with TOPO significantly improved the extraction efficiency (average enrichment factor) of BPs by 51.6 %. After performing single-factor optimization, a Plackett-Burman design was carried out to screen out four key factors, which were further optimized and evaluated by a central composite design. Under the optimal extraction conditions, the proposed method exhibited good linear relationship in the ranges of 0.36–400 μg L −1 ( r 2 ＞0.9994). The limits of detection (LODs) at three times ratio of signal to noise ( S/N = 3) and limits of quantification (LOQs, S/N = 10) for bisphenol A, bisphenol E, bisphenol F and bisphenol S were ranged from 0.11 to 0.49 and 0.36–1.62 μg L −1 , respectively. The intra-day and inter-day precisions ( n = 6) were less than 4.1 % with enrichment factors ranged from 173 to 192. Bisphenol A with concentration of 4.42–13.71 µg/L was detected in real water samples with good recoveries (90.4–105.6 %). The proposed SM-NADES-HF-LLLME/HPLC method proved to be a green alternative for the determination of bisphenoic compounds in environmental waters.
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