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Search results for: 3 Chlorocarbonylphenylboronic anhydride CAS Number [332154 58 2]

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#37387278   // To Up

[Determination of catecholamines in urine by disperse solid-phase extraction-liquid chromatography based on TiCT/polyimide composites].

Neurotransmitters (NTs) are basic signaling chemicals used for communication between cells. The most well-known catecholamines (CAs) are epinephrine, norepinephrine, and dopamine. CAs are an important class of monoamine NTs that contain catechins and amine groups. The accurate determination of CAs in biological samples can provide essential information on potential pathogenic mechanisms. However, biological samples generally contain only trace levels of CAs. Therefore, sample pretreatment is necessary to separate and enrich CAs before instrument analysis. Dispersive solid-phase extraction (DSPE) technology combines the principles of liquid-liquid extraction and solid-phase extraction and is a useful method for purifying and enriching the target analytes in complex matrices. This method has the advantages of low solvent consumption, environmental safety, and high sensitivity and efficiency. In addition, the adsorbents used in DSPE do not need to be packed into a column and can simply be completely dispersed in the sample solution; this excellent feature greatly improves the extraction efficiency and simplifies the extraction process. Therefore, the development of new DSPE materials with high efficiency and adsorption capacity using simple preparation procedures has received wide attention from the research community. Carbon nitrides (MXenes) are a class of two-dimensional layered materials that possess good hydrophilicity, a large number of functional groups (-O, -OH, and -F), large layer spacing, different elemental compositions, excellent biocompatibility, and environmental friendliness. However, these materials have a small specific surface area and poor adsorption selectivity, which limits their applications in SPE. The separation selectivity of MXenes can be significantly improved by functional modification. Polyimide (PI) is a crosslinking product that is mainly formed by the condensation polymerization of binary anhydride and diamine. It has a unique crosslinked network structure, as well as a large number of carboxyl groups, and shows excellent characteristics. Therefore, the synthesis of new PI-functionalized TiCT (TiCT/PI) composites by growing a PI layer on the surface of two-dimensional MXene nanosheets in situ may not only overcome the adsorptive limitations of MXenes but also effectively improve their specific surface area and porous structure, thereby enhancing their mass transfer capacity, adsorption capacity, and selectivity. In this study, a TiCT/PI nanocomposite was fabricated and successfully applied as a DSPE sorbent to enrich and concentrate trace CAs in urine samples. The prepared nanocomposite was examined using various characterization methods, including scanning electron microscopy, Fourier transform-infrared spectroscopy, X-ray diffraction, and zeta potential analysis. The effects of the extraction parameters on the extraction efficiency of TiCT/PI were also investigated in detail. The adsorption performance of TiCT/PI can be described by pseudo-second-order kinetics and the Freundlich isotherm model. The adsorption process appeared to occur on the outer surface, as well as surface voids, of the nanocomposite. The adsorption mechanism of TiCT/PI indicated a chemical adsorption process based on multiple electrostatic, , and hydrogen-bonding interactions. The optimal adsorption conditions included an adsorbent dosage of 20 mg, sample pH of 8, adsorption and elution times of 10 and 15 min, respectively, and eluent composed of acetic acid-acetonitrile-water (5∶47.5∶47.5, v/v/v). A sensitive method for detecting CAs in urine was subsequently developed by coupling TiCT/PI as a DSPE sorbent with HPLC-FLD analysis. The CAs were separated on an Agilent ZORBAX ODS analytical column (250 mm×4.6 mm, 5 μm). Methanol and an aqueous solution of 20 mmol/L acetic acid were used as the mobile phases for isocratic elution. Under optimal conditions, the proposed DSPE-HPLC-FLD method exhibited good linearity in the range of 1-250 ng/mL with correlation coefficients >0.99. The limits of detection (LODs) and limits of quantification (LOQs) were calculated based on signal-to-noise ratios of 3 and 10 and found to be in the range of 0.20-0.32 and 0.7-1.0 ng/mL, respectively. The recoveries of the method were in the range of 82.50%-96.85% with RSDs≤9.96%. Finally, the proposed method was successfully applied to the quantification of CAs in urine samples from smokers and nonsmokers, thereby indicating its applicability for determining trace CAs.
Yuan-Qing Zhao, Kai Hu, Cheng Yang, Peng-Zhao Han, Li-Xin Li, Xiao-Bing Liu, Zhen-Qiang Zhang, Shu-Sheng Zhang

1765 related Products with: [Determination of catecholamines in urine by disperse solid-phase extraction-liquid chromatography based on TiCT/polyimide composites].

100 1 mg100 5 mg20 100 5 mg100 1 mg100 5 mg96 wells

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#24705883   2014/04/03 To Up

Inhaled multiwalled carbon nanotubes modulate the immune response of trimellitic anhydride-induced chemical respiratory allergy in brown Norway rats.

The interaction between exposure to nanomaterials and existing inflammatory conditions has not been fully established. Multiwalled carbon nanotubes (MWCNT; Nanocyl NC 7000 CAS no. 7782-42-5; count median diameter in atmosphere 61 ± 5 nm) were tested by inhalation in high Immunoglobulin E (IgE)-responding Brown Norway (BN) rats with trimellitic anhydride (TMA)-induced respiratory allergy. The rats were exposed 2 days/week over a 3.5-week period to a low (11 mg/m(3)) or a high (22 mg/m(3)) concentration of MWCNT. Nonallergic animals exposed to MWCNT and unexposed allergic and nonallergic rats served as controls. At the end of the exposure period, the allergic animals were rechallenged with TMA. Histopathological examination of the respiratory tract showed agglomerated/aggregated MWCNT in the lungs and in the lung-draining lymph nodes. Frustrated phagocytosis was observed as incomplete uptake of MWCNT by the alveolar macrophages and clustering of cells around MWCNT. Large MWCNT agglomerates/aggregates were found in granulomas in the allergic rats, suggesting decreased macrophage clearance in allergic rats. In allergic rats, MWCNT exposure decreased serum IgE levels and the number of lymphocytes in bronchoalveolar lavage. In conclusion, MWCNT did not aggravate the acute allergic reaction but modulated the allergy-associated immune response.
Yvonne C M Staal, Jos J van Triel, Thérèse V P Maarschalkerweerd, Josje H E Arts, Evert Duistermaat, Hans Muijser, Johannes J M van de Sandt, C Frieke Kuper

2524 related Products with: Inhaled multiwalled carbon nanotubes modulate the immune response of trimellitic anhydride-induced chemical respiratory allergy in brown Norway rats.

50 ul1 mg5ug96T1 100 UG50 ul96T

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#11799847   // To Up

Synthesis and antibacterial activity of 5-nitrofuryl and 3-methoxy-2-nitrophenyl derivatives of 6 beta-aminopenicillanic, 7 beta-aminocephalosporanic and 7 beta-aminodesacetoxy-cephalosporanic acids.

A number of 5-nitrofuryl and 3-methoxy-2-nitrophenyl derivatives of 6 beta-aminopenicillanic (6 beta-APA), 7 beta-aminocephalosporanic (7 beta-ACA) and 7 beta-aminodesacetoxycephalosporanic (7 beta-ADCA) acids were synthesized by the method of mixed anhydrides or via Schiff bases. The chemical structures of the new compounds were confirmed by IR-, 1H-NMR and mass spectral data, obtained by negative ion electrospray ionization. The in vitro testing results indicated that all penicillins and cephalosporins prepared exhibited antibacterial activity equal to or in many cases considerably higher than those of ampicillin (CAS 69-53-4) and cephalexin (CAS 23325-78-2) against the Gram-positive microorganisms, excluding B. subtilis L2, B. subtilis HB2 and S. aureus 1/45 "Oxford". Their activity towards the two strains of Proteus mirabilis was also good being greater than that of cephalexin contrary to the demonstrated lower activity towards all strains of E. coli tested. The most active compounds which simultaneously possessed the broadest spectrum of antibacterial activity proved to be compounds 1 and 8 both bearing as a substituent a 5-nitrofuran group.
R Stoyanova, N Kaloyanov, P Traldi, M Bliznakov

2035 related Products with: Synthesis and antibacterial activity of 5-nitrofuryl and 3-methoxy-2-nitrophenyl derivatives of 6 beta-aminopenicillanic, 7 beta-aminocephalosporanic and 7 beta-aminodesacetoxy-cephalosporanic acids.

5 G100ug Lyophilized100 MG1 g100 MG 5 G1 mg 100 G 1 G 1 G100ug Lyophilized 25 MG

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#12692648   // To Up

NTP Toxicology and Carcinogenesis Studies of Succinic Anhydride (CAS No. 108-30-5) in F344/N Rats and B6C3F1 Mice (Gavage Studies).

Succinic anhydride, a food additive, is also used in the manufacture of polymeric materials, pharmaceuticals, and agricultural and industrial chemicals. NTP Toxicology and Carcinogenesis studies were conducted by administering suspensions of succinic anhydride (97% pure) in corn oil by gavage to groups of F344/N rats and B6C3F1 mice of each sex for 16 or 20 days, 13 weeks, or 2 years. Genetic toxicology studies were conducted in Salmonella typhimurium and Chinese hamster ovary (CHO) cells. Twenty-Day or Sixteen-Day and Thirteen-Week Studies: In the 20-day studies in rats, doses of succinic anhydride given on 14 exposure days ranged from 47 to 750 mg/kg. Compound-related deaths occurred in the groups of males that received 375 mg/kg or higher doses and in females that received 187 mg/kg or higher doses. Necrosis and inflammation of the upper respiratory tract were seen in 3/10 male and 3/10 female rats given 750 mg/kg and 2/10 female rats given 375 mg/kg. In the 16-day studies in mice, doses of succinic anhydride given on 12 exposure days ranged from 219 to 3,500 mg/kg. All animals that received 875 mg/kg or higher doses of succinic anhydride died before the end of the studies. No compound-related lesions were seen in male or female mice examined from the 438 mg/kg dose group. In the 13-week studies in rats, doses of succinic anhydride ranged from 25 to 400 mg/kg for males and from 12.5 to 200 mg/kg for females. Deaths of 8/10 male rats that received 400 mg/kg and 4/10 males and 5/10 females that received 200 mg/kg were compound related. At necropsy, the mean body weights of male rats that received 200 or 400 mg/kg were 9% or 15% lower than that of vehicle controls, whereas the mean body weights of dosed and vehicle control female rats were similar. No compound-related gross or microscopic lesions were observed. In the 13-week studies in mice, doses of succinic anhydride ranged from 37 to 600 mg/kg. All 10 males and 8/10 females that received 600 mg/kg and 2/10 males and 2/10 females that received 300 mg/kg died before the end of the studies. The final mean body weights of mice that received 150 or 300 mg/kg were 13% or 9% lower than that of vehicle controls for males and 8% or 7% lower for females. Mild inflammation of the stomach was observed in 7/10 male mice that received 150 mg/kg and 5/10 males that received 300 mg/kg compared with 2/10 vehicle controls. Based primarily on the effects of administration of succinic anhydride on survival and mean body weights of rats and mice, doses for the 2-year studies were 0, 50, or 100 mg/kgto groups of 60 rats of each sex; 0, 38, or 75 mg/kg to groups of 50 male mice; and 0, 75, or 150 mg/kg to groups of 50 female mice. Succinic anhydride was administered as a suspension in corn oil by gavage, 5 days per week for 103 weeks. Body Weights and Survival in the Two-Year Studies: Mean body weights of high dose rats were 5%-11% lower than those of vehicle controls during the second year of the studies. No significant differences in survival after 2 years were observed between any groups of rats of either sex (male: vehicle control, 36/60; low dose, 33/60; high dose, 32/60; female: 31/60; 27/60; 27/60). For mice, mean body weights of high dose males were generally 5%-12% lower than those of vehicle controls throughout the study. Mean body weights of high dose female mice were 10%-32% lower than those of vehicle controls; mean body weights of low dose female mice were 10%-20% lower than those of vehicle controls. The survival of high dose male mice was significantly greater than that of vehicle controls after week 77 (survival after 2 years--male: 27/50; 30/50; 42/50; female: 37/50; 38/50; 41/50). No other differences in survival were observed between any groups of mice of either sex. Nonneoplastic and Neoplastic Effects in the Two-Year Studies: At no site in rats or mice was there a chemical-related increase in the incidence of nonneoplastic or neoplastic lesions. A sufficient number of animals in each dose group lived long enough to allow evaluation of the potential carcinogenicity ofr of animals in each dose group lived long enough to allow evaluation of the potential carcinogenicity of succinic anhydride. Genetic Toxicology: Succinic anhydride was not mutagenic in S. typhimurium with or without exogenous metabolic activation. The chemical did not induce sister chromatid exchanges or chromosomal aberrations in cultured CHO cells in the presence or absence of exogenous metabolic activation. Conclusions: Under the conditions of these 2-year studies, there was no evidence of carcinogenic activity of succinic anhydride for male or female F344/N rats given 50 or 100 mg/kg succinic anhydride. There was no evidence of carcinogenic activity for male B6C3F1 mice given 38 or 75 mg/kg succinic anhydride or for female B6C3F1 mice given 75 or 150 mg/kg. Synonyms: butanedioic anhydride; dihydro-2,5-furandione; 2,5-diketotetrahydrofuran; succinic acid anhydride; succinyl anhydride; succinyl oxide; tetrahydro-2,5-dioxofuran

1248 related Products with: NTP Toxicology and Carcinogenesis Studies of Succinic Anhydride (CAS No. 108-30-5) in F344/N Rats and B6C3F1 Mice (Gavage Studies).



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#12732897   // To Up

NTP Toxicology and Carcinogenesis Studies of Xylenes (Mixed) (60% m-Xylene, 14% p-Xylene, 9% o-Xylene, and 17% Ethylbenzene) (CAS No. 1330-20-7) in F344/N Rats and B6C3F1 Mice (Gavage Studies).

The technical grade of xylenes (mixed) (hereafter termed xylenes) contains the three isomeric forms and ethylbenzene (percentage composition shown above). The annual production for 1985 was approximately 7.4 x 108 gallons. Xylenes is used as a solvent and a cleaning agent and as a degreaser and is a constituent of aviation and automobile fuels. Xylenes is also used in the production of benzoic acid, phthalate anhydride, and isophthalic and terephthalic acids as well as their dimethyl esters. Toxicology and carcinogenesis studies of xylenes were conducted in laboratory animals because a large number of workers are exposed and because the long- term effects of exposure to xylenes were not known. Exposure for the present studies was by gavage in corn oil. In single-administration studies, groups of five F344/N rats and B6C3F1 mice of each sex received 500, 1,000, 2,000, 4,000, or 6,000 mg/kg. Administration of xylenes caused deaths at 6,000 mg/kg in rats and mice of each sex and at 4,000 mg/kg in male rats. In rats, clinical signs observed within 24 hours of dosing at 4,000 mg/kg included prostration, muscular incoordination, and loss of hind limb movement; these effects continued through the second week of observation. Tremors, prone position, and slowed breathing were recorded for mice on day 3, but all mice appeared normal by the end of the 2- week observation period. In 14- day studies, groups of five rats of each sex were administered 0, 125, 250, 500, 1,000, or 2,000 mg/kg, and groups of five mice of each sex received 0, 250, 500, 1,000, 2,000, or 4,000 mg/kg. Chemical- related mortality occurred only at 2,000 mg/kg in rats and at 4,000 mg/kg in mice. Rats and mice exhibited shallow breathing and prostration within 48 hours following dosing at 2,000 mg/kg. These signs persisted until day 12 for rats, but no clinical signs were noted during the second week for mice. In 13- week studies, groups of 10 rats of each sex received 0, 62.5, 125, 250, 500, or 1,000 mg/kg, and groups of 10 mice of each sex received 0, 125, 250, 500, 1,000, or 2,000 mg/kg. No deaths or clinical signs of toxicity were recorded in rats. However, high dose male rats gained 15% less weight and females 8% less weight than did the vehicle controls. Two female mice died at the 2,000 mg/kg dose. Lethargy, short and shallow breathing, unsteadiness, tremors, and paresis were observed for both sexes in the 2,000 mg/kg group within 5- 10 minutes after dosing and lasted for 15- 60 minutes. Two- year toxicology and carcinogenesis studies were conducted by administering 0, 250, or 500 mg/kg xylenes in corn oil by gavage to groups of 50 F344/N rats of each sex, 5 days per week for 103 weeks. Groups of 50 B6C3F1 mice of each sex were administered 0, 500, or 1,000 mg/kg xylenes on the same schedule. Although the mortality was dose related in male rats (final survival: vehicle control, 36/50; low dose, 26/50; high dose, 20/50), many of the early deaths in the dosed males were gavage related. Body weights of the high dose male rats were 5%- 8% lower than those of the vehicle controls after week 59. The mean body weights of low dose and vehicle control male rats and those of dosed and vehicle control female rats were comparable. Survival rates of female rats and both sexes of dosed mice were not significantly different from those of the vehicle controls. The mean weights of dosed male and female mice were comparable to those of the vehicle controls. Hyperactivity lasting 5- 30 minutes was observed in high dose mice after dosing, beginning after week 4 and continuing through week 103. At no site was the incidence of nonneoplastic or neoplastic lesions in dosed rats or mice of either sex considered to be related to the administration of xylenes. Neither xylenes nor any of its components (o- xylene, m-xylene, p- xylene, or ethylbenzene) were mutagenic when tested with or without metabolic activation in Salmonella typhimurium strains TA100, TA1535, TA97, or TA98 with the preincubation protocol. In addition, ethylbenzene was tested in cytogenetic assays using cultured Cetic assays using cultured Chinese hamster ovary cells both with and without metabolic activation; neither sister- chromatid exchanges nor chromosomal aberrations were induced by ethylbenzene. An audit of the experimental data was conducted for the 2-year studies of xylenes. No data discrepancies were found that influenced the final interpretations. Under the conditions of these 2-year gavage studies, there was no evidence of carcinogenicity of xylenes (mixed) for male or female F344/N rats given 250 or 500 mg/kg or for male or female B6C3F1 mice given 500 or 1,000 mg/kg.

1575 related Products with: NTP Toxicology and Carcinogenesis Studies of Xylenes (Mixed) (60% m-Xylene, 14% p-Xylene, 9% o-Xylene, and 17% Ethylbenzene) (CAS No. 1330-20-7) in F344/N Rats and B6C3F1 Mice (Gavage Studies).

5 G 100 G 100 G 5 G 5 G 100 G 100 G500 MG 25 G 100 G

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