Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 20 de 31
Filter
1.
Front Nutr ; 9: 1034751, 2022.
Article in English | MEDLINE | ID: mdl-36419553

ABSTRACT

Artificial induction of polyploidy is an efficient technique for improving biological properties and developing new varieties of many plants. In this study, we analyzed and compared differences in characteristics (morphological and biological) of diploid and tetraploid Anoectochilus roxburghii plants. We found significant differences between tetraploid plants and their diploid counterparts. The tetraploid plants exhibited dwarfing and stockiness. They were also bigger and had more voluminous roots and larger stomata than the diploid plants. Moreover, the biochemical analyses showed that the contents of some amino acids and minerals elements were significantly higher in tetraploid plants. The chlorophyll content of the leaves exhibited no definitive changes, but the photosynthetic performance was higher in the tetraploid plants. In addition, contents of major bioactive compounds, such as kinsenoside and some flavonoids, were enhanced in tetraploids. This is the first detailed analysis of characteristics in diploid and tetraploid A. roxburghii plants. The results may facilitate breeding programs with the species.

2.
Fish Shellfish Immunol ; 99: 555-561, 2020 Apr.
Article in English | MEDLINE | ID: mdl-32109610

ABSTRACT

Bursicon (burs) is a neuropeptide hormone consisting of two cystine-knot proteins (burs α and burs ß), and burs α-ß is responsible for cuticle tanning in insects. Further studies show that burs homodimers induce prophylactic immunity. Here, we investigated the hypothesis that burs homodimers act in regulating immunity in the red swamp crayfish Procambarus clarkii. We found that burs α and burs ß are expressed in neural system of crayfish. Treating crayfish with recombinant burs-homodimer proteins led to up-regulation of several anti-microbial peptide (AMP) genes, and RNAi-mediated knockdown of burs led to decreased expression of AMP genes. The burs proteins also facilitated bacterial clearance and decreased crayfish mortality upon bacterial infection. Furthermore, burs proteins activated the transcriptional factor Relish, and knockdown of Relish abolished the influence of recombinant burs homodimers on AMP induction. We infer the burs homodimers induce expression of AMP genes via Relish in crayfish and this study extends this immune signaling pathway from insects to crustaceans.


Subject(s)
Arthropod Proteins/genetics , Astacoidea/genetics , Immunity, Innate , Invertebrate Hormones/physiology , Transcription Factors/genetics , Animals , Antimicrobial Cationic Peptides/genetics , Arthropod Proteins/immunology , Astacoidea/immunology , Gene Expression Regulation , Protein Conformation , Signal Transduction , Transcription Factors/immunology
3.
Neuroreport ; 30(17): 1191-1196, 2019 12 10.
Article in English | MEDLINE | ID: mdl-31634239

ABSTRACT

To explore the involvement of hypoxia-inducible factor-1 alpha (HIF-1α) in the upregulation of P-glycoprotein (P-gp) in refractory epilepsy. Brain tissue specimens were collected and analyzed for expression of HIF-1α and P-gp using an immunohistochemical (IHC) staining method in both refractory epilepsy group and control group. Correlation between HIF-1α and P-gp expression level in refractory epilepsy group was analyzed. Then, a hypoxia cell model was established by simulating the nerve cell hypoxic microenvironment in the human U251 cell line using cobalt chloride (CoCl2). Western blot analysis was used to detect expression levels of HIF-1α and P-gp in the hypoxic cell model. Finally, expression of HIF-1α and P-gp was detected using real-time quantitative PCR and Western blot, respectively, after U251 hypoxic model cells were infected with HIF-1α siRNA. IHC scores of HIF-1α and P-gp in refractory epilepsy group were significantly higher than that in control group. In addition, the expression of HIF-1α was positively correlated with the expression of P-gp in refractory epilepsy group. Expression levels of HIF-1α and P-gp in U251 cells cultured with 250 µmol/L CoCl2 for 48 hours were significantly higher than that in controls. After transfection with siRNA targeting HIF-1α, expressions of HIF-1α and P-gp at mRNA and protein level were decreased, respectively, in the hypoxia cell model. HIF-1α may be involved in the upregulation of P-gp in refractory epilepsy through inducement of P-gp expression. Therefore, activation of the HIF-1α/P-gp pathway is one hypothesis proposed to explain the pathogenesis of refractory epilepsy.


Subject(s)
ATP Binding Cassette Transporter, Subfamily B, Member 1/metabolism , Drug Resistant Epilepsy/metabolism , Gene Expression Regulation/physiology , Hypoxia-Inducible Factor 1, alpha Subunit/metabolism , ATP Binding Cassette Transporter, Subfamily B/metabolism , Adult , Female , Humans , Male , Middle Aged , Up-Regulation , Young Adult
4.
Front Psychol ; 10: 583, 2019.
Article in English | MEDLINE | ID: mdl-30941078

ABSTRACT

This study used piecewise growth modeling to describe the developmental trajectories of self-rated health (SRH) in the elderly and longitudinal associations with activities of daily living (ADL), educational level, economic status, age, and gender. Data were drawn from the Chinese Longitudinal Healthy Longevity Survey (CLHLS), collected over 12 years (from 2002 to 2014) at five waves. A total of 16,064 Chinese elders (57.4% females) were analyzed. Results showed two phases of development for SRH; specifically, the decreasing trend of SRH was from slow (in the first phase, waves 1 to 3) to fast (in the second phase, waves 3 to 5). Descriptives showed that the turning point age was at the age of 83.69 (range = 68 to 116, median age = 82 years old). ADL were positively associated with SRH within each time point (wave of data). Female elders had a higher initial state (i.e., worse) of SRH than did male elders, and poorer economic status was associated with worse initial status of SRH.

5.
Heart Surg Forum ; 22(1): E019-E023, 2019 01 28.
Article in English | MEDLINE | ID: mdl-30802192

ABSTRACT

BACKGROUND: To study the effect of miR-29b on myocardial infarction via Notch signaling pathway in rats. METHODS: The rat acute myocardial infarction (AMI) models were established and were divided into AMI group, sham group and normal group (N = 10 in each group). HE (Hemotoxylin and eosin) staining was used to detect whether the model was constructed successfully. MiR-29b mimics, inhibitors, mimics negative control (NC) were transfected into H9c2 (2-1) cells. Then, cells were divided into a mimics group, inhibitor group, NC group, and blank group. The relative expression levels of miR-29b, Notch1, DII4 and Hesl were detected by qRT-PCR. The expression of NICD1 was detected by Western blotting. RESULTS: The rat AMI model was successfully constructed. Compared with normal and sham groups, the miR-29b expression was down-regulated, while the expression of Notch1, DII4 and Hesl was increased, and the NICD1 protein expression was increased in the myocardial infarction area of the AMI group (P < .05). Compared with the NC and blank groups, the relative expression of Notch1, DII4, Hesl and NICD1 were upregulated in the mimics group (P < .05), whereas the expression of Notch1, DII4, Hesl and NICD1 in the inhibitor group was decreased (P < .05). CONCLUSION: MiR-29b inhibited myocardial fibrosis and cardiac hypertrophy by activating the Notch signaling pathway and protected myocardium against myocardial infarction.


Subject(s)
Gene Expression Regulation , MicroRNAs/genetics , Myocardial Infarction/genetics , RNA/genetics , Receptor, Notch1/genetics , Ventricular Remodeling , Animals , Blotting, Western , Disease Models, Animal , Male , MicroRNAs/biosynthesis , Myocardial Infarction/metabolism , Myocardial Infarction/physiopathology , Rats , Real-Time Polymerase Chain Reaction , Receptor, Notch1/metabolism , Signal Transduction
6.
Arch Gynecol Obstet ; 299(3): 891-899, 2019 03.
Article in English | MEDLINE | ID: mdl-30656442

ABSTRACT

PURPOSE: Diabetic women appear to have adverse pregnancy outcomes. Although there were two meta-analyzes that examined the association between health care and adverse pregnancy outcomes, their results were limited because they only included congenital anomaly and perinatal mortality, and they did not clarify the detailed situations of diabetes and health care. This meta-analysis aims to completely evaluate the effects of health care in improving adverse pregnancy outcomes among diabetic mothers. METHODS: CNKI, EMBASE, Web of Science, and PubMed databases were searched for eligible studies up to December 2017, without any restrictions. Relevant cohort studies characterizing the relationship between health care and adverse pregnancy outcomes were selected for inclusion in the meta-analysis. We also screened the reference list of relevant studies. The fixed-effect models or random-effect models were used to calculate the risk estimates. The potential sources of heterogeneity were explored by stratified and sensitivity analyzes. RESULTS: Twenty-one studies with 6685 cases were included in our analysis. Health care was associated with significantly decreased risk of congenital anomaly (RR 0.237; 95% CI 0.166-0.338), perinatal death (RR 0.457; 95% CI 0.294-0.712), large for gestational age (LGA) (RR 0.794; 95% CI 0.640-0.986), and neonatal hypoglycemia (RR 0.672; 95% CI 0.486-0.929). Publication bias was not found in most results, with the exception of congenital anomaly and small for gestational age (SGA). CONCLUSION: Health care is associated with decreased risk of congenital anomaly, perinatal death, LGA, neonatal hypoglycemia.


Subject(s)
Diabetes, Gestational , Pregnancy Complications/etiology , Female , Humans , Infant, Newborn , Pregnancy , Pregnancy Outcome
7.
Birth ; 46(2): 222-233, 2019 06.
Article in English | MEDLINE | ID: mdl-30284325

ABSTRACT

BACKGROUND: The association between active maternal smoking and congenital malformations is well established, but little is known about the association between secondhand smoke and congenital malformations. Moreover, studies regarding the association between congenital malformations and secondhand smoke have not yielded consistent results. METHODS: In July 2018, we searched PubMed, EMBASE, and China Biology Medicine databases for observational studies characterizing the relationship between secondhand smoke and congenital malformations of offspring in nonsmoking women. Two reviewers independently decided on whether a study should be included, did data extraction, and assessed study quality. Pooled risks with 95% confidence intervals were calculated using either the fixed-effects models or random-effects models. Further subgroup analyses and sensitivity analyses were performed to explore the potential source of heterogeneity and to examine the robustness of risk estimates. RESULTS: Thirty-three studies with a total of 31 944 cases and 32 335 controls were included. Secondhand smoke exposure was associated with an increased risk of congenital malformations (odds ratio = 1.92; 95% confidence interval 1.61-2.30). Secondhand smoke was correlated with significantly increased risk for digestive system (1.17 [1.05-1.32]), nervous system (1.74 [1.33-2.29]), and cardiovascular system (2.10 [1.32-3.35]) malformations and for oral clefts (1.87 [1.47-2.39]). CONCLUSIONS: Secondhand smoke exposure increases the risk for overall and several organ-system malformations. These findings highlight the necessity of improving community awareness to prevent secondhand smoke exposure during the preconception and conception periods.


Subject(s)
Congenital Abnormalities/etiology , Prenatal Exposure Delayed Effects , Tobacco Smoke Pollution/adverse effects , Female , Humans , Infant, Newborn , Infant, Newborn, Diseases/etiology , Pregnancy , Risk Assessment
8.
J Sep Sci ; 36(14): 2323-9, 2013 Jul.
Article in English | MEDLINE | ID: mdl-23630192

ABSTRACT

Benzoylurea (BU) insecticides have contributed greatly to the output of crops. Their residue in the environment put serious threats on human health and environmental safety. In this study, we have established a new, rapid, and reliable method for the monitoring of typical BU insecticides such as diflubenzuron, flufenoxuron, triflumuron, and chlorfluazuron with dispersive liquid-liquid microextraction prior to HPLC. Chlorobenzene and ethanol were employed as the extraction solvent and disperser solvent, respectively. The possible parameters which would influence the extraction efficiency such as the kinds and volumes of extraction and disperser solvents, extraction time, sample pH, centrifuging time, and salting-out effect were optimized in detail. Under the optimal conditions, the linear range of proposed method was in the range of 1.0-70 µg/L. The detection limits varied from 0.24 to 0.82 µg/L and the precision of the method was <6.5% (RSD, n = 6). The proposed method was validated with real water samples and satisfactory spiked recoveries were achieved. All these results indicate that the proposed method is a low cost, easy to operate, efficient, and sensitive method for the analysis of BU insecticides in water samples.


Subject(s)
Chromatography, High Pressure Liquid/methods , Insecticides/analysis , Insecticides/isolation & purification , Liquid Phase Microextraction/methods , Phenylurea Compounds/analysis , Phenylurea Compounds/isolation & purification , Water Pollutants, Chemical/analysis , Water Pollutants, Chemical/isolation & purification , Limit of Detection
9.
J Environ Sci Health B ; 48(3): 191-7, 2013.
Article in English | MEDLINE | ID: mdl-23356340

ABSTRACT

The goal of the present study was to investigate the feasibility of silicon dioxide (SiO(2)) microspheres without special modification to enrich dichlorodiphenyltrichloroethane (DDT) and its main metabolites, p,p'-dichlorodiphenyl-2,2-dichloroethylene (p,p'-DDD) and p,p'-dichlorodiphenyldichloroethylene (DDE) in combination with gas chromatography-electron-capture detection. The experimental results indicated that an excellent linear relationship between the recoveries and the concentrations of DDT and its main metabolites was obtained in the range of 0.2-30 ng mL(-1) and the correlation coefficients were in the range of 99.96-99.99%. The detection limits based on the ratio of signal to the baseline noise (S/N = 3) were 2.2, 2.9, 3.8 and 4.1 ng L(-1) for p,p'-DDD, p,p'-DDT, o,p'-DDT, and p,p'-DDE, respectively. The precisions of the proposed method were all below 10% (n = 6). Four real water samples were utilized for validation of the proposed method, and satisfactory spiked recoveries in the range of 72.4-112.9% were achieved. These results demonstrated that the developed method was a simple, sensitive, and robust analytical method for the monitoring of pollutants in the environment.


Subject(s)
DDT/chemistry , DDT/isolation & purification , Gas Chromatography-Mass Spectrometry/methods , Solid Phase Extraction/methods , Water Pollutants, Chemical/chemistry , Water Pollutants, Chemical/isolation & purification , Adsorption , Environmental Monitoring , Silicon Dioxide/chemistry , Solid Phase Extraction/instrumentation
10.
Chemosphere ; 90(2): 338-43, 2013 Jan.
Article in English | MEDLINE | ID: mdl-22921656

ABSTRACT

Fungicides have been widely used throughout the world, and the resulted pollution has absorbed great attention in recent years. Present study described an effective measurement technique for fungicides including thiram, metalaxyl, diethofencarb, myclobutanil and tebuconazole in environmental water samples. A micro-solid phase extraction (µSPE) was developed utilizing ordered TiO(2) nanotube array for determination of target fungicides prior to a high performance liquid chromatography (HPLC). The experimental results indicated that TiO(2) nanotube arrays demonstrated excellent merits on the preconcentration of fungicides, and excellent linear relationship between peak area and the concentration of fungicides was obtained in the range of 0.1-50 µg L(-1). The detection limits for the targeted fungicides were in the range of 0.016-0.086 µg L(-1) (S/N=3). Four real environmental water samples were used to validate the applicability of the proposed method, and good spiked recoveries in the range of 73.9-114% were achieved. A comparison of present method with conventional solid phase extraction was made and the results exhibited that proposed method resulted in better recoveries. The results demonstrated that this µ-SPE technique was a viable alternative for the analysis of fungicides in complex samples.


Subject(s)
Fungicides, Industrial/analysis , Nanotubes/chemistry , Solid Phase Microextraction/methods , Titanium/chemistry , Water Pollutants, Chemical/analysis , Chromatography, High Pressure Liquid , Fungicides, Industrial/chemistry , Water Pollutants, Chemical/chemistry
11.
J Sep Sci ; 35(24): 3569-74, 2012 Dec.
Article in English | MEDLINE | ID: mdl-23166097

ABSTRACT

Present study described a simple, environmental benign, easy to operate, and determination method for fungicides including thiram, metalaxyl, diethofencarb, myclobutanil, and tebuconazole. The method is based on temperature-controlled ionic liquid dispersive liquid phase microextraction coupled to HPLC with ultraviolet detector. In the enrichment procedure, ionic liquid 1-octyl-3-methylimidazolium hexafluorophosphate [C(8)MIM][PF(6)] was used as the extraction solvent. Variable affecting parameters such as the volume of [C(8)MIM][PF(6)], temperature, extraction time, centrifuging time, and salting-out effect have been optimized in detail. Under the optimal conditions, this method has been found to have good linear relationship in the concentration range of 1.0-100 µg/L and excellent detection sensitivity with LODs (S/N = 3) in the range of 0.32-0.79 µg/L. Precisions of proposed method were in the range of 3.7-5.9% for intraday and 7.8-11.0% for interday (RSDs, n = 6). The proposed method was used for the analysis of real water samples and good spiked recoveries at two different spiked levels were achieved in the range of 84.6-102%.


Subject(s)
Chromatography, High Pressure Liquid/methods , Fungicides, Industrial/analysis , Liquid Phase Microextraction/methods , Spectrophotometry, Ultraviolet/methods , Temperature , Osmolar Concentration
12.
J AOAC Int ; 95(5): 1534-40, 2012.
Article in English | MEDLINE | ID: mdl-23175990

ABSTRACT

This paper reports a new method for the determination of aromatic amines with temperature-controlled ionic liquid dispersive liquid-phase microextraction in combination with HPLC and results of investigation of the influence of anions in ionic liquids on the extraction performance. In these experiments, 1-octyl-3-methylimidazolium hexafluorophosphate ([C8MIM][PF6]), 1-octyl-3-methylimidazolium bis (trifluoromethanesulfonyl) imide ([C8MIM][NTf2]), and 1-octyl-3-methylimidazolium tetrafluoroborate ([C8MIM][BF4]) were used as the extraction solvents for the investigation of the effect of anions in ionic liquids. Other parameters affecting the microextraction performance were also investigated. Under the optimal conditions, the proposed method had good linearity over the concentration ranges of 1.0-100 microg/L for 2, 4-dimethylaniline, 2-chloroanline, and N,N-dimethylaniline, and 1.5-150 microg/L for N,N-dimethylaniline and alpha-naphthylamine, with excellent correlation coefficients (R2 > or = 0.999), excellent detection sensitivity with LODs (S/N = 3) in the range of 0.39-0.63 microg/L, and precision in the range of 3.2-5.4% RSD (n = 6). Real water samples were analyzed with the established method, and good spike recoveries in the range of 86.3 to 98.9% were obtained. These results indicated that this method would be useful in the routine analysis of such pollutants.


Subject(s)
Amines/chemistry , Ionic Liquids/chemistry , Liquid Phase Microextraction/methods , Water Pollutants, Chemical/chemistry , Chromatography, High Pressure Liquid/methods , Hydrogen-Ion Concentration , Temperature , Time Factors , Water/chemistry
13.
Article in English | MEDLINE | ID: mdl-22934999

ABSTRACT

The goal of present study was to investigate the applicability of nanoscale zerovalent iron (NZVI) on the degradation of 1-(2-chlorobenzoyl)-3-(4-chlorophenyl) urea (CCU) under aerobic and anaerobic conditions, respectively. The experimental results showed that NZVI could effectively degrade CCU, but the removal efficiencies were different under these two different conditions. The best removal efficiencies for CCU were 90.2 and 75.8% under aerobic and anaerobic conditions, respectively. The highly oxidative hydroxyl radicals and reductively hydrogen would account for the rapid degradation of CCU under aerobic and anaerobic conditions, respectively. The experimental results also showed that surfactant Tween 20 significantly inhibited the degradation of CCU under aerobic conditions. However it markedly enhanced the degradation of CCU under anaerobic condition.


Subject(s)
Environmental Pollutants/chemistry , Environmental Restoration and Remediation/methods , Insecticides/chemistry , Iron/chemistry , Metal Nanoparticles/chemistry , Urea/analogs & derivatives , Aerobiosis , Anaerobiosis , Juvenile Hormones/chemistry , Microscopy, Electron, Scanning , Urea/chemistry
14.
J Chromatogr A ; 1237: 24-9, 2012 May 11.
Article in English | MEDLINE | ID: mdl-22464436

ABSTRACT

Present study investigated the applicability of ordered TiO(2) nanotube arrays for the enrichment and determination of polychlorinated biphenyls (PCBs) in water samples. A new and reliable method was developed for the preconcentration and determination of PCBs by micro-solid phase equilibrium extraction in combination with gas chromatography and electron capture detection (GC-ECD), which exploited the special physical and chemical properties of ordered TiO(2) nanotube arrays. The experimental results indicated that low LODs were easily achieved in the range of 0.02-0.10 µg L(-1) for PCB-28, PCB-52, PCB-101, PCB-153, PCB-138, and PCB-180. The proposed method was validated with several real water samples, and good spiked recoveries have been obtained in the range of 95.8-110.5%. The experimental results demonstrated that TiO(2) nanotube arrays could be reused for over 200 times without the lost of the extraction efficiency. All these showed that TiO(2) nanotube arrays would be very useful in the enrichment and determination of trace pollutants.


Subject(s)
Nanotubes , Polychlorinated Biphenyls/analysis , Titanium/chemistry , Water Pollutants, Chemical/analysis , Chromatography, Gas , Hydrogen-Ion Concentration , Limit of Detection , Microscopy, Electron, Scanning
15.
Talanta ; 85(3): 1598-602, 2011 Sep 15.
Article in English | MEDLINE | ID: mdl-21807227

ABSTRACT

Present study described a simple, sensitive, and viable method for the determination of bisphenol A, 4-n-nonylphenol and 4-tert-octylphenol in water samples using temperature-controlled ionic liquid dispersive liquid-phase microextraction coupled to high performance liquid chromatography-fluorescence detector. In this experiment, 1-octyl-3-methylimidazolium hexafluorophosphate ([C(8)MIM][PF(6)]) was used as the extraction solvent, and bisphenol A, 4-n-nonylphenol and 4-tert-octylphenol were selected as the model analytes. Parameters affecting the extraction efficiency such as the volume of [C(8)MIM][PF(6)], dissolving temperature, extraction time, sample pH, centrifuging time and salting-out effect have been investigated in detail. Under the optimized conditions, good linear relationship was found in the concentration range of 1.0-100 µg L(-1) for BPA, 1.5-150 µg L(-1) for 4-NP, and 3-300 µg L(-1) for 4-OP, respectively. Limits of detection (LOD, S/N=3) were in the range of 0.23-0.48 µg L(-1). Intra day and inter day precisions (RSDs, n=6) were in the range of 4.6-5.5% and 8.5-13.3%, respectively. This method has been also successfully applied to analyze the real water samples at two different spiked concentrations and excellent results were obtained.


Subject(s)
Chromatography, High Pressure Liquid/methods , Liquid Phase Microextraction/methods , Phenols/analysis , Water Pollutants, Chemical/analysis , Benzhydryl Compounds , Environmental Monitoring/methods , Fresh Water/analysis , Fresh Water/chemistry , Humans , Imidazoles/chemistry , Ionic Liquids/chemistry , Reproducibility of Results , Rivers/chemistry , Sewage/analysis , Sewage/chemistry , Solvents/chemistry , Spectrometry, Fluorescence/methods , Temperature
16.
J Hazard Mater ; 193: 82-9, 2011 Oct 15.
Article in English | MEDLINE | ID: mdl-21807462

ABSTRACT

This paper described a simple and novel analytical technique for the determination of polycyclic aromatic hydrocarbons (PAHs) in environmental water samples. A micro-solid phase extraction (µ-SPE) was developed utilizing cetyltrimethylammonium bromide modified ordered TiO(2) nanotube array. The experimental results indicated that modified TiO(2) nanotube arrays demonstrated an excellent merit on the preconcentration of PAHs, and there were excellent linear relationships between peak area and the concentration of PAHs in the range of 0.2-100 µg L(-1) and 1.0-100 µg L(-1), respectively. The detection limits of proposed method for the targeted PAHs were in the range of 0.026-0.82 µg L(-1) (S/N = 3). The real-world environmental water samples were used to validate the applicability of the proposed method and good spiked recoveries were in the range of 75.0-114%. All these results demonstrated that this new µ-SPE technique was a viable alternative to conventional enrichment techniques for the extraction and analysis of PAHs in complex samples.


Subject(s)
Cetrimonium Compounds/chemistry , Nanotubes , Polycyclic Compounds/analysis , Titanium/chemistry , Water Pollutants, Chemical/analysis , Cetrimonium , Chromatography, High Pressure Liquid , Hydrogen-Ion Concentration , Limit of Detection , Microscopy, Electron, Scanning , Solid Phase Microextraction
17.
J Hazard Mater ; 189(1-2): 48-53, 2011 May 15.
Article in English | MEDLINE | ID: mdl-21398026

ABSTRACT

This paper established a new, rapid and sensitive method for the determination of lead in water samples preconcentrated by dispersive liquid-liquid microextraction (DLLME) prior to atomic fluorescence spectrometry. Dithizone was used as the chelating agent. In the DLLME procedure, lead formed lead-dithizone complex and migrated into the carbon tetrachloride micro-droplets. Important factors that would affect the extraction efficiency had been investigated including the kind and volume of extraction solvent and dispersive solvent, sample pH, the amount of chelating agent, extraction time and centrifugation time. The results showed that the coexisting ions containing in water samples had no obvious negative effect on the determination of lead. The experimental results indicated that the proposed method had a good linear range of 0.01-100 ng mL(-1) (r(2) = 0.9990). The precision was 2.12% (RSD, n = 7) and the detection limit was 0.95 ng L(-1). Proposed method was validated with four real environmental samples and the results indicated that the proposed method was excellent for the future use and satisfied spiked recoveries were in the range of 92.9-97.4%.


Subject(s)
Lead/analysis , Water Pollutants, Chemical/analysis , Water/analysis , Chemical Fractionation/methods , Limit of Detection , Reproducibility of Results , Spectrophotometry, Atomic/methods
18.
Anal Bioanal Chem ; 400(1): 205-12, 2011 Apr.
Article in English | MEDLINE | ID: mdl-21344165

ABSTRACT

Ordered TiO(2) nanotube arrays have been widely used in many fields such as photocatalysis, self-cleaning, solar cells, gas sensing, and catalysis. This present study exploited a new functional application of the ordered TiO(2) nanotube arrays. A micro-solid phase equilibrium extraction using ordered TiO(2) nanotube arrays was developed for the enrichment and measurement of organochlorine pesticides prior to gas chromatography-electron capture detection. Ordered TiO(2) nanotube arrays exhibited excellent merits on the pre-concentration of organochlorine pesticides and lower detection limits of 0.10, 0.10, 0.10, 0.098, 0.0076, 0.0097, 0.016, and 0.023 µg L(-1) for α-HCH, ß-HCH, γ-HCH, δ-HCH, p,p'-DDE, p,p'-DDD, o,p'-DDT, and p,p'-DDT, respectively, were achieved. Four real water samples were used for validation, and the spiked recoveries were in the range of 78-102.8%. These results demonstrated that the developed micro-solid phase equilibrium extraction using ordered TiO(2) nanotube arrays would be very constructive and have a great beginning with a brand new prospect in the analysis of environmental pollutants.


Subject(s)
Hydrocarbons, Chlorinated/analysis , Nanotubes , Pesticides/analysis , Titanium/chemistry , Water Pollutants, Chemical/analysis , Chromatography, Gas , Hydrogen-Ion Concentration , Limit of Detection , Microscopy, Electron, Scanning , Reproducibility of Results
19.
Anal Methods ; 3(2): 356-361, 2011 Feb 01.
Article in English | MEDLINE | ID: mdl-32938036

ABSTRACT

This paper developed a new method with temperature controlled ionic liquid dispersive liquid-phase microextraction for the determination of pyrethroid insecticides such as fenpropathrin, fenvalerate and bifenthrin in water samples. The effect of alkyl chain length of ionic liquid 1-alkyl-3-methylimidazolium hexafluorophosphate and other parameters such as sample pH, temperature, salting-out effect and sample volume on the extraction efficiency were investigated in detail. Four different alkyl chain length ionic liquids ([CnMIM][PF6], n = 4, 6, 7, 8) were tested. The experimental results demonstrated that the alkyl chain length of ionic liquids (ILs) did have an important role on the extraction efficiency. The experimental results indicated that the longer alkyl chain length of ILs resulted in better extraction efficiency. Among the four ILs, 1-octyl-3-methylimidazolium hexafluorophosphate [C8MIM] [PF6] was the best one for extraction of the target analytes. Under the optimized conditions, three pyrethroid insecticides had limits of detection (LOD, S/N = 3) in the range of 0.34∼0.48 µg L-1. The precisions of the proposed method (RSDs, n = 6) with a spiked concentration of 20 µg L-1 were in the range of 2.0∼3.4%. The proposed method was evaluated with real water samples spiked at a concentration of 10 ng mL-1 and good spiked recoveries over the range of 89.2∼102.7% were obtained.

20.
Anal Methods ; 3(3): 653-658, 2011 Mar 01.
Article in English | MEDLINE | ID: mdl-32938086

ABSTRACT

This paper established a new determination method for phenols using temperature-controlled ionic liquid dispersive liquid-phase microextraction prior to high-performance liquid chromatography. In this experiment, 1-octyl-3-methylimidazolium hexafluorophosphate ([C8MIM][PF6]) was employed as the extraction solvent for the enrichment of 2-chlorophenol, 2-naphthol, 2,4-dinitrophenol, and 2,4-dichlorophenol. Parameters that may affect the extraction efficiency including the volume of [C8MIM][PF6], dissoluble temperature, extraction time, sample pH, amount of ethanol, centrifugation time and salting-out effect have been investigated in detail. Under the optimal conditions, they have good linear relationships over the concentration range of 1.0-100 ng mL-1 for 2-chlorophenol, 2-naphthol, 2,4-dinitrophenol, and 1.5-150 ng mL-1 for 2,4-dichlorophenol, and excellent detection sensitivity with limits of detection (LOD, S/N = 3) in the range of 0.27-0.68 µg L-1. Intra day and inter day precisions of the proposed method (RSDs, n = 6) were 2.1-3.7% and 5.1-7.2%, respectively. The proposed method has been successfully applied to analyze real water samples spiked with two different concentrations and good spiked recoveries over the range of 85.8-117.0% were obtained. These results indicated that the proposed method would be competitive in the analysis of phenols in the future.

SELECTION OF CITATIONS
SEARCH DETAIL
...