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Simultaneous Determination of 10 Kinds of Algal Toxins in Water Samples by Online Solid Phase Extration Coupled with Ultra High Performance Liquid Chromatography- Quadrupole Linear Ion Trap Mass Spectrometry

Ying Xiao XU ; Zhu LIU ; Qi Bing ZHU ; Jing Jing LIANG ; Qin Wan CHEN ; Wen Jin LUO

Chinese Journal of Analytical Chemistry.2017;45(11):1703-1710. doi:10.11895/j.issn.0253-3820.170339

An online solid phase extraction ( online-SPE) combined with ultra high performance liquid chromatography-quadrupole linear ion trap mass spectrometry (UHPLC-MS / MS-Qtrap) was established for the simultaneous identification and determination of 10 kinds of algal toxins in water samples. Multiple injections of water samples were controlled by a preset program, and the target analytes were enriched by trap column. The six-way valve was switched subsequently, and the algal toxins in the trap column were back-flushed to the analytical column for separation and analysis. The results showed that the online SPE significantly simplified pretreatment process, and the linear ion trap tandem mass spectrometry improved the sensitivity of the determination. Moreover, the establishment of enhanced product ion (EPI) scan library provided evidence for the confirmation of algal toxins. The 10 kinds of algal toxins showed a good linear relationship with correlation coefficient R2>0. 99. The limits of detection (LOD) were 0. 0015 -0. 0050 μg / L. The mean recoveries at three spiked levels of 0. 02, 0. 1, 1. 0 μg / L were from 83. 7% to 98. 5% . The method was suitable for the rapid confirmation and quantitative determination of various algal toxins in water.

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Rapid Quantitative Detection and Model Optimization of Trans Fatty Acids in Edible Vegetable Oils by Near Infrared Spectroscopy

Xin Xin MO ; Tong SUN ; Hua Mu LIU ; Nan Zhen YE

Chinese Journal of Analytical Chemistry.2017;45(11):1694-1702. doi:10.11895/j.issn.0253-3820.170329

Near infrared spectroscopy (NIR) was used to detect trans fatty acids (TFA) in edible vegetable oils quantitatively. And prediction model of TFA was optimized through band selection, pretreatment method, variable selection and modeling method. NIR spectra of 98 edible vegetable oil samples were collected in spectral range of 4000-10000 cm-1 using an Antaris Ⅱ Fourier transform near infrared spectrometer, and the true content of TFA was measured by gas chromatography. First, optimization of waveband and pretreatment method was conducted on original spectra. On this basis, competitive adaptive reweighted sampling (CARS) was used to select important variables that related to TFA. Finally, the prediction models of TFA content in edible vegetable oils were established using principal component regression ( PCR), partial least square (PLS) and least square support vector machine (LS-SVM). The results indicated that NIR spectroscopy was feasible for detecting TFA content in edible vegetable oils, R2 of the best prediction model after optimized in calibration and prediction sets were 0. 992 and 0. 989, and root mean square error of calibration (RMSEC) and root mean square error of prediction ( RMSEP) were 0. 071% and 0. 075% , respectively. Only 26 variables were used in the best prediction model, accounting for 0. 854% of the whole waveband variables. In addition, compared with the full waveband PLS prediction model, the R2 in prediction set increased from 0. 904 to 0. 989, and RMSEP decreased from 0. 230% to 0. 075% . It shows that model optimization is very necessary, CARS method can select important variables related to TFA effectively and immensely reduce the number of modeling variables, so it can simplify the prediction model, and greatly improve the accuracy and stability of prediction model.

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Determination of Organophosphorus Pesticide Residues in Fruits and Vegetables Using Porous Carbon Nanoparticles Based on Citrus Compose

Yu Ke REN ; Lin Wen ZHANG ; Rui Shu CAO ; Xian Cun XI ; Min Guo WANG ; Qin Zhi ZHOU

Chinese Journal of Analytical Chemistry.2017;45(11):1669-1677. doi:10.11895/j.issn.0253-3820.170224

Porous carbon nanoparticles ( NPC) were prepared by ZnCl2 activation and carbonization using citrus waste as carbon source. A sample pretreatment method with NPC as dispersive solid phase extraction (d-SPE ) absorbent was established for the determination of organophosphorus pesticides in fruits and vegetables by gas chromatography. The NPC was characterized by scanning electron microscopy (SEM), X-ray diffraction ( XRD), FT-IR spectra, Raman spectroscopy, Brunauer, Emmett and Teller surface area(BET). Those results showed that the NPC was an amorphous porous carbon material with pore size in the range of 0-15 nm. Its specific surface area and pore volume were 1243 m2 / g and 1. 28 cm3 / g, respectively. The analysis conditions, including the amount and clean up time of adsorbent, were optimized by analysis of 14 kinds of oranophosphorus pesticides in fruits and vegetables with gas chromatography-flame photometric determination(GC-FPD). Moreover, the comparison for NPC with commercial materials of PSA, C18 and GCB was investigated in this study. The results indicated that the purification time was only 2 min using 0. 01 g NPC. The cost of NPC was about 25% of C18 , 21% of PSA and 16% of GCB. Because of the porous structure of NPC, the purification efficiency was significantly higher than the three commercial materials mentioned above. Under the optimum conditions, the calibration curves of the 14 organophosphorus pesticides were linear in the range of 0. 02-1. 00 mg / L with good correlation coefficients (R2>0. 99) and detection limits (S / N=3) of 0. 63-5. 30 μg / kg. The recoveries of the pesticides at three spiked levels ranged from 71. 3% to 114. 7%with the relative standard deviations (RSDs) of 0. 9% -12. 9% . The method is simple, rapid, sensitive, and low cost, and can satisfy the requirements of detection of organophosphorus pesticide residues in fruits and vegetables, displaying a good application prospect.

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Components and Their Antioxidant Activity of Essential Oil of Herba Artimisiae Sieversianae from Different Growth Periods

Heng Zhi SUN ; Lan Min LYU ; Jia Zhi ZHANG ; Ying ZHANG ; Jun Xiao HAN

Chinese Journal of Analytical Chemistry.2017;45(11):1655-1661. doi:10.11895/j.issn.0253-3820.170333

The effective exploitation of natural products is of great significance. Herein the essential oil from Herba Artimisiae Sieversianae in growth period and flower/ fruit bearing period was extracted by ethanol extraction method. The optimal extraction condition was determined by orthogonal experiment, including extracting 3 times, soaking for 90 min, and the ratios of liquid to solid for Herba Artimisiae Sieversianae in growth period and flower/ fruit bearing period were 10 mL : 1 g and 8 mL : 1 g, respectively. The main components of the products were confirmed by FT-IR and GC-MS, which were cineole, camphor, d-borneol, caryophyllene, cadina-1, 4-diene, calamenene, ethyl palmitate, etc. in herba artimisiae sieversianae in growth period, and camphor, caryophyllene, borneol, neryl formate, etc. in Herba Artimisiae Sieversianae in flower/ fruit bearing period. The radical scavenging activity of the products was determined. The results showed that the IC50 values of the essential oil from Herba Artimisiae Sieversianae in growth period and flower/fruit bearing period for 0. 05 mmol/ L DPPH solution were 0. 40 mg / mL and 1. 66 mg / mL, respectively. The essential oil extracted by ethanol from Herba Artimisiae Sieversianae was confirmed to possess good antioxidant activity.

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Determination of Seven Urinary Metabolites of Organophosphate Esters Using Liquid Chromatography-Tandem Mass Spectrometry

Pei LI ; Ying Xiang ZENG ; Tao Jun CUI ; Juan Ling ZHAO ; Qiang Zhi YU

Chinese Journal of Analytical Chemistry.2017;45(11):1648-1654. doi:10.11895/j.issn.0253-3820.171027

A simple method was developed for simultaneous determination of seven urinary metabolites of organophosphate esters by liquid chromatography-tandem mass spectrometry (LC-MS / MS). Based on different physical and chemical properties of these OPs metabolites, the solid phase extraction cartridges and the washing and eluting solvents were optimized in details. Furthermore, the mobile phase and mass spectrometric parameters were also investigated. The results showed that Oasis WAX cartridge was the best SPE column in this study, and 2 mL of NH3 ·H2 O (5% ) in methanol and 2 mL of methanol were chosen as the eluting solvents. The recoveries of six analytes were ranged from 60. 5% to 104. 0% , whereas DEP ranged from 17. 8% to 36. 2% . Seven analytes could be baseline separated from each other under the optimized chromatographic conditions. The limits of detection and quantification of seven analytes ranged from 0. 005 to 0. 2 μg / L and 0. 02 to 0. 5 μg / L, respectively. The standard deviations of response repeatability for intra-day and inter-day period were lower than 15. 4% . This method was finally applied to determination of metabolites of OPs from 10 urines from general population in Guangzhou city. The concentrations of total OPs metabolites in urine samples ranged from 0. 5 to 6. 7 μg / L.

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Research on Cataluminescence Type Formaldehyde Sensor Based on CeO2-Co3 O4 Nanofibers

Jiang Ming HU ; Wang Chun LYU ; Bin Shi YANG ; Zhong WANG

Chinese Journal of Analytical Chemistry.2017;45(11):1621-1627. doi:10.11895/j.issn.0253-3820.170221

CeO2-Co3 O4 composite nanofibers were prepared by the double jets electrospinning method. The nanofibers were then deposited onto the surface of a ω-type heating coil as cataluminescence material to prepare a new cataluminescence ( CTL ) type formaldehyde gas sensor. The crystalline phase and microstructure of CeO2-Co3 O4 composite nanofibers were characterized by X-ray diffraction ( XRD) and scanning electron microscope (SEM), and the cataluminescence mechanism and electrochemical characteristic of formaldehyde on the surface of CeO2-Co3 O4 nanofibers were analyzed by H2 temperature programmed reduction (H2-TPR) and X-ray photoelectron spectroscopy (XPS). Under the optimal conditions (500 nm of wavelength, 0. 2 L/ min of flow rate and 550℃), there was a good relationship between the CTL intensity of this formaldehyde gas sensor (Ce30) and formaldehyde concentration in the range of 1. 2 -50 μg / m3 , the sensitivity was 40. 04 a. u. / (μg / m3 ), the detection limit was 1. 2 μg / m3 , the dynamic response time and recover time of formaldehyde gas were 2. 4 s and 3. 5 s, respectively. The formaldehyde sensor was successfully applied to the determination of formaldehyde in the automotive exhaust, with relative errors of 0. 39% -1. 07% and relative standard deviations of less than 3% .

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Continuously Monitoring of Concentration of Extracellular Ascorbic Acid in Spinal Cord Injury Model

Yang LYU ; Wen Ya ZHANG ; Lei TAN ; Liang Wen JI ; Ping YU ; Qun Lan MAO ; Fang ZHOU

Chinese Journal of Analytical Chemistry.2017;45(11):1595-1599. doi:10.11895/j.issn.0253-3820.171091

Acute traumatic spinal cord injury (SCI) represents one of the most devastating injuries that afflict the human body. Ascorbic acid ( AA) plays an important role in mammalian central nervous system, especially in SCI. In this study, the change of AA concentration after SCI was investigated by using an on-line electrochemical method integrated with in vivo microdialysis. A microdialysis probe (2 mm in length) was implanted into the spinal cord of an anesthetized rat (Thoracic-10). Microdialysis perfusate (2 μL/ min) was collected in the sample loop of an on-line injector for direct injection onto a glassy carbon electrode which was modified with the heat-treated single-walled carbon nanotubes (SWNTs). Normal ascorbic acid concentration in the extracellular fluids of spinal cords was (26. 17 ± 1. 25) μmol/ L (n =8). The experimental spinal cord injury, induced by a lesion at T-10, significantly increased the extracellular ascorbic acid levels to (53. 24± 1. 95) μmol/ L (n =8). This study provides the experimental evidence on the essential roles of ascorbic acid in spinal cord injuries.

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Development of Nano-Polymerase Chain Reaction and Its Application

Ming Fu SANG ; Xin LI ; Jia LIU

Chinese Journal of Analytical Chemistry.2017;45(11):1745-1753. doi:10.11895/j.issn.0253-3820.170097

Polymerase chain reaction (PCR) has become one of the powerful technique since its invention in 1980s. Nevertheless, PCR technique is still frequently impaired by its low specificity, poor sensitivity, false positive results, etc. Recently, nanomaterials including metal nanoparticles, carbon nanomaterials, quantum dots and nano metal oxide have been added into PCR solution to improve both quality and productivity of PCR. The nanoparticles assisted PCR ( NanoPCR) has received considerable attentions due to its unprecedented sensitivity, selectivity and efficiency. In this view, the mainly used nanoparticles in NanoPCR, including gold nanoparticles, quantum dots, carbon nanomaterials, graphene and metallic oxide, was firstly summarized. And then, the possible mechanisms for highly improved sensitivity and selectivity were discussed. Finally, recent applications of NanoPCR were described.

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Advance in Bacteria Chemotaxis on Microfluidic Devices

Qian Xiao ZANG ; Yu Zhe LI ; Yan Xiao ZHANG ; Lei JIANG ; Qi Nan REN ; Kai SUN

Chinese Journal of Analytical Chemistry.2017;45(11):1734-1744. doi:10.11895/j.issn.0253-3820.170259

Chemotaxis is the response ability of motile cells to chemicals gradients in environment and the migration toward higher concentration of chemoattractant or lower concentration of repellent. This mechanism is a basic nature of microorganisms to adapt to the environmental changes. The research of microbial chemotaxis is of great significance in utilizing bacteria to solve environment problems, control the pathogen infection, and develop microbial industrial projects. Microfluidic devices can realize qualitatively and quantitatively detect of bacterial chemotaxis. In comparison with traditional detect methods, microfluidic assay has an accurate control over bacterial microenvironment, with a higher sensitivity. In the past few years, bacterial chemotaxis study based on microfluidic assay was developed rapidly. In this paper, the microfluidic chemotaxis detectors that appeared in recent years were introduced from the aspect of chip structure, working principle and their applications. Finally, we provided insights into the challenges of bacterial chemotaxis and provided future perspectives.

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Capillary Electrophoresis Fingerprint of Arnebia Euchroma (Royle) Johnst.

Lei ZHANG ; Qin Ai ZHANG ; Man WANG ; Yi Gang SHEN

Chinese Journal of Analytical Chemistry.2017;45(11):1727-1733. doi:10.11895/j.issn.0253-3820.171120

A method of capillary electrophoresis fingerprint was developed for evaluation of the quality of Arnebia euchroma ( Royle) Johnst. The samples were separated on a 50 μm × 40 cm uncoated capillary separation column at separation voltage of 25 kV with 100 mmol/ L borate buffer ( pH 8. 0) containing 25 mmol/ L SDS and 20% (V/ V) dehydrated alcohol as running buffer. The injection volume of sample was 0. 5 psi ×5 s and the detection wavelength was 214 nm. The results indicated that the samples of Arnebia euchroma (Royle) Johnst were well separated and detected in 35 min. With Shikonin peak as reference peak, 6 characteristic peaks of standard Arnebia euchroma (Royle) Johnst were determined. The quality discriminant analyses were accomplished for different kinds of samples named Arnebia euchroma ( Royle) Johnst that purchased from eight sources by means of characteristic fingerprint peak analysis, similarity evaluation and cluster analysis. This method had good reproducibility, and could be used for the quality control of Arnebia euchroma (Royle) Johnst.

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