Tetrabutylammonium particle

Table IV. Extrathermodynamic Assumption Based on Scaled Particle Theory Calculations for a Tetrabutylammonium Particle in Water - - Acetone Mixtures at 298.15 Ka 5...

Some reviews [5-7] have appeared on NCE-electrospray ionization-mass spectrometry (NCE-ESI-MS) discussing various factors responsible for detection. Recently, Zamfir [8] reviewed sheathless interfacing in NCE-ESI-MS in which the authors discussed several issues related to sheathless interfaces. Feustel et al. [9] attempted to couple mass spectrometry with microfluidic devices in 1994. Other developments in mass spectroscopy have been made by different workers. McGruer and Karger [10] successfully interfaced a microchip with an electrospray mass spectrometer and achieved detection limits lower than 6x 10-8 mole for myoglobin. Ramsey and Ramsey [11] developed electrospray from small channels etched on glass planar substrates and tested its successful application in an ion trap mass spectrometer for tetrabutylammonium iodide as model compound. Desai et al. [12] reported an electrospray microdevice with an integrated particle filter on silicon nitride. 

Figure 9.112 Separation of substrates and products of reaction catalyzed by adenylosuccinate synthetase. Column Prepacked C18 /xBondapak, 10 /im particle size. Mobile phase 65 mM potassium phosphate, 1 mM tetrabutylammonium phosphate, 10% methanol at pH 4.4. Absorbance was measured at 254 nm. (From Rossomando, 1987.)...

The application of ultrasound dramatically increases the rate of exfoliation of HxTi2 x/404 yH20 in the presence of aqueous tetrabutylammonium (TBA) hydroxide [130]. The effect of ultra sonication power and processing time on particle size distributions are evaluated. Applied powers of 60-300 W and reaction times of 2-30 min effectively reduce the H-Ti particle size to <100 nm. Both particle size distribution analysis and UV-Vis spectroscopy were used to study the effect of the... 

Several reversed-phase methods were also developed which do not use a C18 column. A reversed-phase method using a C8 Spherisorb column has been reported (54) to quantitate diltiazem and two of its metabolites (N-monodemethyl diltiazem and desacetyl diltiazem). A 10 pm particle size PRP-1 column (55), mobile phase of 60% acetonitrile and 0.01 M aqueous KH2PO4, 40% 0.005M aqueous tetrabutylammonium hydroxide and UV absorbance detection at 254 nm was used to determine diltiazem present in plasma. Several HPLC methods have been developed which use a cyano-bonded column. One such method was developed for the determination of diltiazem and its metabolite desacetyl diltiazem in human plasma (56). The analytes are extracted from plasma made basic with 0.5M aqueous dibasic sodium phosphate (pH 7.4) using 1% 2-propanol in hexane. The method uses a cyanopropylsilane column with a mobile phase of 45% acetonitrile and 55% 0.05M aqueous acetate buffer (pH 4.0). The minimum detectable limit was 2 ng/mL in plasma. A similar HPLC method was developed by Johnson and Pieper (57) for the determination of diltiazem and three of its metabolites. Also, an HPLC method was developed (58) for the analysis of diltiazem and desacetyl diltiazem in plasma using UV detection at 237 nm, a Zorbax CN 6 pm particle size column and a mobile phase of 45% methanol, 55% 0.05M aqueous ammonium dihydrogen phosphate and 0.25% triethylamine adjusted to pH 5. 

The Carbon Black Pearls labeled BP 2000 was supplied by Cabot Corp. 10 g of carbon black pearls (BP-2000) was dried in an oven at 110 °C overnight. In a 200-mL flask, 17.2 g of 40 % tetrabutylammonium hydroxide, 2.5 g of I BO and 15.1 g of ethanol was stirred to obtain a homogeneous solution. The dried carbon black was impregnated with this solution to incipient wetness. After evaporation of ethanol at room temperature for 12 h, carbon particles were impregnated with 19.3 g of tetraethyl orthosilicate. This mixture was left at ambient conditions to hydrolyze overnight. The hydrothermal synthesis was performed in a Teflon-lined autoclave at 180 °C for 72 h. Then the autoclave was cooled, a solid product was filtered and washed with distilled water. Calcination was carried out in a muffle oven at 550 °C for 18 h [86],... 

Figure 3 Typical chromatograms showing speciation analyses of As(lll), As(V), MMA(V), DMA(V), MMA(lll), and DMA(lll) in deionized water (a), a urine sample (b), and the urine sample spiked with MMA(lll) (c), DMA(lll) (d), and As(V) (e). Separation was carried out on an ODS-3 column (15 cm X 4.6 mm, 3- rm particle size Phenomenex) with a mobile phase (pH 5.95) containing 5 mM tetrabutylammonium hydroxide, 3 mM malonic acid, and 5% methanol. The flow rate of the mobile phase was 1.2 ml/min. The column was maintained at 50°C. A hydride generation atomic fluorescence detector was used for detection of arsenic. Peaks labeled 1-6 correspond to As(lll), MMA(Itl), DMA(V), MMA(V), DMA(lll), and As(V) respectively. The urine sample was collected from a person 4 hr after the administration of 300 mg sodium 2,3-dimercapto-l-propane sulfonate (DMPS). For clarity, chromatograms were manually shifted on vertical axis. (Adapted from Ref. 96.)...

MEH-PPV can be synthesized by a liquid-solid two-phase reaction [24], The liquid phase consists of l,4-bis-(chloromethyl)-2-methoxy-5-(2 -ethylhexyloxy)benzene dissolved in tetrahydrofuran (THF) and tetrabutylammonium bromide as a phase transfer catalyst. The solid phase consists simply of small-sized potassium hydroxide particles. The reaction is sketched in Figure 3.10. 

Gold nanoparticles (2.5-7.5 nm diameter) were obtained by Martino and others [402] by reduction of AUCI4 via lithium borohydride in tetrahydrofuran in the reverse micelle system DDAB (didodecyldimethylammonium bromide)/toluene. A purple-colored gold colloid was observable. The particles were encapsulated by silica gels formed in the micellar system by hydrolysis-condensation of TEOS or a prehydrolyzed TEOS, already added in the system. Gelation of silica was achieved by the addition of tetrabutylammonium hydroxide (quicker in case of pre-hydrolyzed TEOS). The particle size was found to be independent of reaction stoichiometry, gel precursor type (TEOS/pre-hydrolyzed TEOS) and the washing step after synthesis. 

Ion pairing agents in liquid-liquid systems in reversed-phase mode have included dihydrogenphos-phate for separation of tricyclic amines, octyl sulfate for catecholamines, and tetrabutylammonium for aromatic carboxylates and anions of sulfonamides, to exemplify some of the comparatively few applications. Liquid stationary phases coated on the alkyl-bonded phase include 1-pentanol, butyronitrile, and tributylphosphate. In normal-phase liquid-liquid ion pair chromatography aqueous perchlorate solution has been coated on to silica particles for ion pair separation of catecholamines and related compovmds and tetrabutylammonium ion at neutral pH for carboxylates and anions of sulfonamides. The organic mobile phase often contained dichloromethane and butanol. In the normal-phase mode on silica alternative separation systems have been described with aqueous perchloric acid in methanol added to dichloromethane as mobile phase for separation of amines such as drug substances. This is not an extensively utilized, but quite useful, kind of separation, which has been named ion pair adsorption chromatography. 

A direct reaction between titanium alkoxides and tetraalkylammonium hydroxides brought quite interesting results. The addition of titanium isoprpoxide into aqueous solution of 15% tetramethylammonium hydroxide afforded an opaque colloidal solution. This opaque solution turned transparent within a few hoius, and a clear 1 mol/1 solution was obtained. The solution was basic with pH 13. The use of tetrabutylammonium hydroxide and tetrapropylammonium hydroxide also led to the same reaction (Ohya et al., 2002). The clear solution consisted of colloidal particles, which could be recognized by laser scattering, and the diameter of the particle was 15 nm, estimated by a dynamic laser scattering. 

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