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11.
Cyanuric chloride (2,4,6-trichloro-1,3,5-triazine) can be determined by fastscan differential pulse polarography in methanolic acetate buffer solution at pH 5.6 at a hanging mercury drop electrode. At positive potentials, the insoluble salt formed between cyanuric chloride and mercury(I) is adsorbed on the mercury surface and the d.p.p. current is enhanced. The detection limit is 0.2gmg ml?1. Cyanuric chloride in air can be determined after absorption in methanol. 相似文献
12.
Tomcík P Jencusová P Krajcíková M Bustin D Brescher R 《Analytical and bioanalytical chemistry》2005,383(5):864-868
An interdigitated microelectrode array (IDA) was applied to the determination of formaldehyde released from textiles produced
in industry. The proposed method is based on formaldehyde reaction with hypobromite which is formed in weakly basic media
by control current electrooxidation of bromide on the generator segment of the IDA array. The unreacted hypobromite diffuses
through the gap between individually polarisable IDA segments and it is amperometrically detected on the collector segment
of the IDA. The efficiency of this nonconvective transfer process in the absence of formaldehyde was substantially higher
(78%) in comparison with that when using the rotating ring disc electrode. The influence of the added formaldehyde on the
transfer process can be utilised to develop a simple and sensitive analytical procedure for formaldehyde detection with a
detection limit of 4×10−6 mol dm−3. 相似文献
13.
An efficient and mild one‐pot synthesis of bis(oxazoline) (BOX) ligands is developed from reactions of dicarboxy dichlorides with β‐amino alcohols in the presence of 11.0 equiv. NEt3 followed by the addition of 3.6 equiv. methanesulfonyl chloride (MsCl). Nine different BOX ligands were prepared in excellent yields of ≥ 80%. Advantages of this improved synthesis are mild reaction conditions, short total reaction time of 9 h, and high isolated yields. 相似文献
14.
15.
It is well known how the Kostant-Rowen Theorem extends the validity of the famous Amitsur-Levitzki identity to skew-symmetric matrices. Here we give a general method, based on a graph theoretic approach, for deriving extensions of known permanental-type identities to skew-symmetric and symmetric matrices over a commutative ring of prime characteristic. Our main result has a typical Kostant-Rowen flavour: IfM≥p[n+1/2] then $C_M (X,Y) = \sum\limits_{\alpha ,\beta \in Sym(M)} {x_{\alpha (1)} y_{\beta (1)} x_{\alpha (2)} y_{\beta (2)} } ...x_{\alpha (M)} y_{\beta (M)} = 0$ is an identity onM n ? (Ω), the set ofnxn skew-symmetric matrices over a commutative ring Ω withp1Ω=0 (provided that $P > \sqrt {[n + 1/2)} $ ). Otherwise, the stronger conditionM≥pn implies thatC M(X,Y)=0 is an identity on the full matrix ringM n(Ω). 相似文献
16.
Jenö Kóbor Ferenc Fülöp M. Sami El-Gharib Gábor Bernáth 《Journal of heterocyclic chemistry》1984,21(1):149-153
A large number of 4-substituted-9,10-dialkoxy-1,6,7,11b-tetrahydropyrimido[6,1-a]isoquinolin-2-ones were prepared by the reaction of 1-(ethoxycarbonylmethyl)-6,7-dialkoxy-1,2,3,4-tetrahydroisoquinolines with iminoethers. Reaction of the corresponding isoquinoline-1-acetic acid derivatives with iminoethers led to the formation of N-acyl-1,2,3,4-tetrahydroisoquinolin-1-acetamides. In the hydrolysis of the prepared 4-substituted-pyrimido[6,1-a]isoquinolin-2-ones, the corresponding N-acyl-1,2,3,4-tetrahydroisoquinolin-1-acetamides were obtained. While reduction of the 4-phenyl derivative resulted in the corresponding 1,3,4,6,7,11b-hexahydropyrimidinone. The steric structures of the tetrahydro- and hexahydropyrimido[6,1-a]isoquinolines were determined by nmr spectroscopy. 相似文献
17.
Wolfgang Hnle Walter Schmettow Karl Peters Jen‐Hui Chang Hans Georg von Schnering 《无机化学与普通化学杂志》2004,630(12):1858-1862
The novel ternary polyphosphides M4P21I (M = K, Rb) have been synthesized from the elements in single crystalline form, representing further examples for the formation of mixed crystals between simple salts and binary phosphides. They form as ruby‐red platelets and dark‐red prisms, respectively, and are only slightly sensitive to moisture and oxygen. The compounds are isotypic (Ccmm (no 63); Z = 4; oP104; K4P21I: a = 12.853Å; b = 21.795Å; c = 9.748Å; 1168 hkl, R = 0.033; Rb4P21I: a = 13.281Å; b = 21.868Å; c = 9.771Å; 777 hkl, R = 0.053) and feature corrugated 2D networks formed from two different types of polymerized P7 units. The networks form large cavities filled by M+ and I‐ ions. Zigzag chains of condensed trigonal M6 prisms, centered by the I‐ anions, separate the polyphosphide nets. The mean homoatomic P‐P bond length (d = 2.216Å) corresponds to a P‐P single bond. However, the individual P‐P distances vary with position and function (2.126 ‐ 2.247Å) and these are compared with those of the isolated P21‐3 anion. 相似文献
18.
In this study, the separation mechanism employed in hydrodynamic chromatography in microchannel devices is analyzed. The main purpose of this work is to provide a methodology to develop a predictive model for hydrodynamic chromatography for biological macromolecules in microchannels and to assess the importance of various phenomenological coefficients. A theoretical model for the hydrodynamic chromatography of particles in a microchannel is investigated herein. A fully developed concentration profile for non-reactive particles in a microchannel was obtained to elucidate the hydrodynamic chromatography of these particles. The external forces acting on the particles considered in this model include the van der Waals attractive force, double-layer force as well as the gravitational force. The surface forces, such as van der Waals attractive force as well as the double-layer repulsive force, can either enhance or hinder the average velocity of the macromolecular particles. The average velocity of the particles decreases with the molecular radius because the van der Waals attractive force increases the concentration of the particles near the channel surface, which is the low-velocity region. The transport velocity of the particles is dominated by the gravity and the higher density enlarges the effect caused by gravity. 相似文献
19.
A simple, rapid, and eco-friendly analytical method for simultaneous determination of uric acid and creatinine in urine applying high performance liquid chromatography (HPLC) is described. After dilution, de-protein, and filtration, the sample solution was injected to separate the species with C-18 column by an eluent containing 0.05 M ammonium phosphate buffer at pH 7.4. An UV detector was used to monitor the separation of species at 235 nm. Optimum conditions for separation and detection were investigated. Results indicated that under optimized condition measurements were achieved within 13 min. The detection limits were 0.127 and 0.156 mug ml(-1) for uric acid and creatinine respectively. The recovery was 95% (0.57% RSD) for uric acid and 99.2% (0.98% RSD) for creatinine, from five measurements. Real urine specimens were tested. 相似文献
20.
Investigation of the root extract of Antidesma pentandrum var. barbatum led to the isolation of seven new compounds, antidesmol ( 1 ), antidesmanins E ( 2 ) and F ( 3 ), antidesnone ( 4 ), antidesnol ( 5 ), barbatumols A ( 6 ) and B ( 7 ), together with 14 known compounds including sodium aristolochate‐I ( 10 ) and aristolochic acid‐I methyl ester ( 11 ). 相似文献