Ammonium acetate, solution preparation

While stirring, slowly add 40 ml methanol/ammonium acetate solution prepared in step 1. 

Isolation of dry, normal ammonium acetate, prepared by neutralizing acetic acid with anhydrous ammonia or ammonium carbonate, is difficult because of ammonia loss during evaporation of water. Consequendy, commercial grades of ammonium acetate are often mixtures of the neutral and acid salts, or are suppHed as ammonium acetate solution [8013-61-4]. 

Ammonium acetate is prepared by the reaction of equal amounts of ammonium hydroxide and acetic acid. Determine the concentration of all solute species present in 0.100 M NH4CH3C02(aq). 

The tetraethylammonium-Beta (TEA-3) zeolites used in this work have been synthesized following the procedure described in the literature (5). Samples with Si/Al ratios between 7 and 106 (as measured by chemical analysis) and crystallite sizes in the range of 0.2-0.9 ym (as measured by scanning microscopy) were obtained. The H-form of these zeolites was prepared in the following way the TEA-3 samples were heated at 550 C for 3 hours by slowly increasing the calcination temperature (5°C min l), with one-hour intermediate steps at 350 and 450 C. After this treatment all TEA molecules had been removed from the zeolite (as monitored by IR spectroscopy). In a second step, the zeolite was exchanged with 1 M ammonium acetate solution and then heated at 550°C for 3 hours as described. 

V-containing silicalite (Al- and Na-free) samples were prepared hydrothermally and then treated with an ammonium acetate solution at room temperature in order to remove extralattice vanadium. Three samples with Si02A 203 ratios of 117, 237 and 545, respectively, were prepared. Hereinafter these samples will be referred to as follows V-SH117, V-SU237 and V-SH545. Details on the preparation procedure, and characterization of the samples have been reported previously (7,2). 

The sodium-ammonium forms (Na-NH4-X and Na-NH4-Y) were prepared by repeated exchange of the sodium zeolite with ammonium acetate solutions at room temperature. The sodium-hydrogen forms (Na-H-X and Na-H-Y) were obtained by heating the ammonium zeolite at 380°C for 15 hours. 

Where atomic absorption spectrophotometry is possible the ammonium acetate extract can be directly analysed for Ca and Mg. The spectrophotometric standards are prepared in the ammonium acetate solution and both the standard and extracts are read against ammonium acetate as blank. If AAS is not possible the calcium and magnesium are analysed by complexometric titrations using ethylene diamine tetra acetic acid (EDTA). 

Prepare a blank solution by taking 100 ml ammonium acetate solution by the same procedure. 

In a typical synthesis of Zr-Sil-2 (B), a solution of 0.48 g of Zr(acac)4 in 50 g of acetone was added to 21.25 g of TEOS. After stirring for 30 min., 25.95 g of TBAOH was added dropwise. The solution thus obtained was kept under stirring for 1 h. Finally, 27 g of water was added to it. After stirring for 30 min, the clear gel (pH = 12.3) was transferred to a teflon- lined autoclave and crystallized under similar conditions as those of Zr-Sil-2 (A). Samples having different Zr concentrations ( Si/Zr < 300) were synthesized using two different zirconium sources. The resultant material was filtered, washed with deionized water, dried at 383 K and calcined at 823 K for 16 h. All the Zr-Sil-2 samples were treated with 1 M ammonium acetate solution to remove alkali metal impurities. For comparison, a silica polymorph with MEL structure (Silicalite-2) and a Zr-impregnated Silicalite-2 samples were prepared [10]. 

Methanol/1 M anunonium acetate (1 1) one part methanol is mixed with one part of the 1 M ammonium acetate solution. This solution should be prepared every day. 

Amorphous silica was prepared by mixing the silica gel powder Aerosil A-175 with ammonium acetate solution. The obtained paste was molded via extmsion and dried in air first at room temperature, then at 100 C for 10-15h. The samples were calcined under air flow at 550 °C for 10-15h. a-Alumina was obtained via thermal decomposition of Y-AI2O3 for 12h at T = 1250 °C. yAlumina was obtained via thermal decomposition of pseudoboehmite at 500 C for 5 h. The latter was synthesized via aluminium nitrate solution treatment with ammonia. 

This chapter provides an in-depth protocol for our recendy reported cellular preparation procedure a simple wash and dry procedure using an iso-osmotic ammonium acetate solution and a gentle argon drying procedure (30). This method sufficiently cleans individual cells for unobscured mass spectral analysis while at the same time preserving the molecular content of the cells... 

Silver fulminate (SF) is a white crystalline material with heat of formatiOTi 179 kJ mol [15]. It crystallizes in the form of small rosettes or star-shaped clusters. Two polymorphic forms have been reported—orthorhombic and trigonal. The crystal shape depends on reaction conditions (temperature, concentration) during sUver fulminate preparation [94]. Recrystallization from ammonia leads to needles and multiple growths of leaf-like habits [92]. Long (4—5 mm) needle-shaped crystals were prepared by Singh and investigated by X-ray analysis. It was found that the crystal is orthorhombic [95]. The crystal structure of SF was later investigated in detail by Britton and Dunitz [96, 97] and their results were confirmed by Barrick et al. [98]. Ammonium acetate solution ( 20 %) is recommended as the solvent for... 

Basic LA sometimes appears in service lead azide in trace amounts [19]. This substance may be prepared by recrystaUization of a-LA from a 5 % ammonium acetate solution containing free ammonia to a pH of 8.7. The product takes the form... 

Each variation was repeated four times in plots of 25 m of which 15.25 m were used in order to avoid edge effects. The plots were randomized as is accepted procedure in such tests. Soil samples were taken from each plot in the Ap horizon by the so-called compound sample technique. From each plot samples of vegetable parts were taken such as stalks, leaves, seeds, fruit tubers in quite representative quantities. The preparation of the soil was performed in such a way as to get fine soil as required by the various analytical methods used in the determination of the relevant physical and chemical parameters and in accordance with the pertinent official methods [3]. The exchangeable cations were determined according to a method proposed by Casalicchio and others. More specifically the soluble nickel was extracted from the soil with distilled water at a ratio of 1 5 with a shaker for 60 minutes, and in ammonium acetate solution and EDTA at a ratio of 1 10, shaking time 60 minutes. 

PbF2 is readily prepared by the action of hydrogen fluoride on lead hydroxide, lead carbonate, or a-lead oxide. It can also be obtained by precipitation from lead nitrate or lead acetate solutions using potassium fluoride, ammonium fluoride, or ammonium bifluoride. 

After the flask has been cooled by immersion in ice water, 44 g- (o-5 mole) of dry ethyl acetate (Note i) in an equal volume of ether is added over a period of twelve minutes. The cooling bath is removed and stirring is continued for ten minutes. When the reaction flask has again been cooled by the ice-water bath, a previously prepared ammonium chloride solution (Note 2) is added, very slowly at first, over a period of ten minutes, during which a pasty solid separates. 

The o-aminophenylpropiolic acid 4 (20 g) in water (60 mL) and aqueous ammonia (9 mL, d = 0.88) was added with shaking during 15 minutes to a mixture prepared from ferrous sulfate (220 g), water (440 mL), and aqueous ammonia (110 mL, d = 0.88). After 45 minutes, with occasional shaking but no external cooling, the suspension was filtered. The residue was washed with water, and the combined filtrates were treated with ammonium acetate (60 g) and made weakly acidic with acetic acid. The solution was then cooled to 0°C by addition of crushed ice, and then made acidic to Congo-red with concentrated hydrochloric acid (70-80 mL). Additional hydrochloric acid (20 mL, 2 N) was immediately added, and the turbid solution which resulted was diazotized with 20% aqueous sodium nitrite, after which the mixture was kept at 70°C. The cinnoline acid 6 was separated over 45 minutes as a dark brown, granular solid (12.5 g), m.p. 260-265°C. ... 

Either the Mohr titration or the adsorption indicator method may be used for the determination of chlorides in neutral solution by titration with standard 0.1M silver nitrate. If the solution is acid, neutralisation may be effected with chloride-free calcium carbonate, sodium tetraborate, or sodium hydrogencarbonate. Mineral acid may also be removed by neutralising most ofthe acid with ammonia solution and then adding an excess of ammonium acetate. Titration of the neutral solution, prepared with calcium carbonate, by the adsorption indicator method is rendered easier by the addition of 5 mL of 2 per cent dextrin solution this offsets the coagulating effect of the calcium ion. If the solution is basic, it may be neutralised with chloride-free nitric acid, using phenolphthalein as indicator. 

Thorium oxide on activated carbon was prepared by absorption of thorium nitrate from its solution in anhydrous acetone on the activated carbon Supersorbon. The excess solution was decanted, the catalyst was dried at 80 °C, and the adsorbed thorium oxide was decomposed by excess 5% ammonium hydroxide solution. After repeated washing and decanta-nation with distilled water and acetone, the catalyst was dried at 180°C. It was then stabilized by heating to 360°C for 5 hr in a stream of nitrogen. The content of thorium oxide was 2.9% (wt.). The BET surface area was 870 m2/g. Prior to kinetic measurements, the catalyst was modified by passing over acetic acid vapors (100 g acid/1 g catalyst). 

The SI70 supernatant (220 ml) was made to 40 % saturation with solid ammonium sulfate, stirred for 20 min, and then the precipitate was collected by centrifugation at 15,000 g for 15 min. The precipitate was suspended in small volume of buffer B-50 at pH 7.6 containing 20 mM HEPES/KOH, 0.1 mM EDTA, 1 mM dithiothreitol, 10 % (v/v) glycerol, and 50 mM potassium acetate. The 60 % saturated ammonium sulfate solution was prepared similarly. Protein concentrations for 0 - 40 % and 40 - 60 % ammonium sulfate fractions were 4.2 mg/ml and 4.7 mg/ml, respectively. 

At least four chromatographic standards prepared at concentrations equivalent to 50-70% of the limit of quantitation (LOQ) up to the maximum levels of analytes expected in the samples should be prepared and analyzed concurrently with the samples. In LC/MS/MS analysis, the first injection should be that of a standard or reagent blank and should be discarded. Then, the lowest standard should be injected, followed by two to four blanks, control samples, fortifications or investigation samples, followed by another chromatographic standard. This sequence is then repeated until all the samples have been injected. The last injection should be that of a standard. In order to permit unattended analysis of a normal analysis set, we recommend that samples and standards be made up in aqueous solutions of ammonium acetate (ca 5 mM) with up to 25% of an organic modifier such as acetonitrile or methanol if needed. In addition, use of a chilled autosampler maintained at 4 °C provides additional prevention of degradation during analysis. 

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