Ammonium acetate hydroxide

Mehta et al. (26) separated guanine on PEI-cellulose with triethylammonium bicarbonate (TEAB) 0.5 M pH 7.6. Good separation of cyclics, phosphates and nucleosides was evident. Trifilo and Dobson (27) separated cyclic purines by PEI, ammonium acetate/hydroxide-ethanol at pH 9.0. One dimension, ascending, from triphosphates to nucleobases. Gulyassy and Farrand (28) also separated cyclic purines with PEI in 0.4 M acetic, then 0.125 M LiCl. Manhandhar and Dyke (29) separated GTP with PEI and luciferase, water and then 1.4 M LiCl for 50 min. Assay was by scintillation counter. 

Ammonium acetate solutions formed by neutralizing acetic acid using ammonium hydroxide are essentially neutral. Thus, these solutions are suitable for standardization of electrodes, and for use as titration standards. Solutions must be used while fresh, however, as they become acidic on standing. 

For binder preparation, dilute hydrochloric or acetic acids are preferred, because these faciUtate formation of stable silanol condensation products. When more complete condensation or gelation is preferred, a wider range of catalysts, including moderately basic ones, is employed. These materials, which are often called hardeners or accelerators, include aqueous ammonia, ammonium carbonate, triethanolamine, calcium hydroxide, magnesium oxide, dicyclohexylamine, alcohoHc ammonium acetate, and tributyltin oxide (11,12). 

AMMO 2.5 EC , cypermetlu-in, 13 Ammonia, 13 Ammonium acetate, 13 Ammonium arsenate, 13 Ammonium benzoate, 13 Ammonium bicarbonate, 13 Ammonium bifluoride, 14 Ammonium bisulfite, 14 Ammonium carbamate, 14 Ammonium carbonate, 14 Ammonium chloride, 14 Ammonium chlorplatmate, 14 Ammonium clu omate, 14 Ammonium citrate, 14 Ammonium diclu omate, 14 Ammonium fluoride, 14 Ammonium fomiate, 15 Ammonium hexafluorosilicate, 15 Ammonium hydroxide, 15 Ammonium metavanadate, 15 Ammonium molybdate, 15 Ammonium nitrate, 15 Ammonium oxalate, 15 Ammonium perfluorooctanoate, 15 Ammonium persulfate, 15 Ammonium phosphate, 15 Ammonium picrate, 16 Ammonium salicylate, 16... 

A green chemistry variation makes use of solventless conditions to minimize the waste stream from reactions of this type. To a mortar are added aldehyde 67, ketone 68 and solid sodium hydroxide. The mixture is ground and within 5 minutes aldol product 69 is produced. Addition of the second ketone and further grinding affords the 1,5-diketone 70, which can be isolated and cyclized to pyridine 71 with ammonium acetate. The authors report that this method can substantially reduce the solid waste (by over 29 times) and is about 600% more cost effective than previously published procedures. 

Balabanov et al. [499] investigated the efficiency of different solutions for the washing of niobium hydroxide. The effectiveness of water and solutions of ammonia, NH4OH, ammonium acetate, CH3COONH4, and ammonium carbonate, (NH4)2C03, were tested. It was shown that ammonium acetate interacts with solid ammonium oxyfluoroniobates yielding niobium oxide even at temperatures as low as 125°C. The interaction that takes place between the solid components can be presented as follows (144) ... 

Beryllium is sometimes precipitated together with aluminium hydroxide, which it resembles in many respects. Separation from aluminium (and also from iron) may be effected by means of oxine. An acetic (ethanoic) acid solution containing ammonium acetate is used the aluminium and iron are precipitated as oxinates, and the beryllium in the filtrate is then precipitated with ammonia solution. Phosphate must be absent in the initial precipitation of beryllium and aluminium hydroxides. 

Weak acids with weak bases. The titration of a weak acid and a weak base can be readily carried out, and frequently it is preferable to employ this procedure rather than use a strong base. Curve (c) in Fig. 13.2 is the titration curve of 0.003 M acetic acid with 0.0973 M aqueous ammonia solution. The neutralisation curve up to the equivalence point is similar to that obtained with sodium hydroxide solution, since both sodium and ammonium acetates are strong electrolytes after the equivalence point an excess of aqueous ammonia solution has little effect upon the conductance, as its dissociation is depressed by the ammonium salt present in the solution. The advantages over the use of strong alkali are that the end point is easier to detect, and in dilute solution the influence of carbon dioxide may be neglected. 

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). 

Formic acid Ammonium hydroxide Ammonium acetate" Ammonium formate"... 

Acetonitrile (ACN), HPLC grade Ammonium acetate (NH4OAC), reagent grade Ammonium hydroxide, 28%, reagent grade Autosampler vials and septa caps Celite, or equivalent... 

Acetonitrile Water DME (10% or less) DMSO (10% or less) Acetic acid Eormic acid Ammonium acetate Ammonium hydroxide Trifluoroacetic acid (TEA) Triethylamine (TEA) Carbon disulfide... 

Fuhrmann and Werrbach [32] used a field test for the quantitative detection of primaquine in urine. Filter urine and place 10 mL in a 50-mL graduated cylinder. Add 1 mL of 25% ammonium hydroxide and 20 mL ammonium acetate and shake... 

Propanol/ethyl acetate/ water/25% ammonium hydroxide/ pyridine/3.85% aqueous ammonium acetate... 

Therefore, the way to ensure reproducible adduct formation is to use mobile-phase additives (e.g. ammonium acetate or formate, formic, acetic or trifluoroacetic acid (in APCI), ammonium hydroxide, etc.). Their application in the mobile phase can be an effective way to improve the intensity of the MS signal and LC-MS signal correlation between matrix and standard samples. However, it is observed that some additives like trifluoroacetic acid or some ion-pairing agents (triethyl-amine) may play a role in ionisation suppression [3]. In addition, high concentrations of involatile buffers will cause precipitation on, and eventually blocking of, the MS entrance cone, leading to a fast decrease of sensitivity. For the in volatile NaAc buffer, it is advisable to maintain... 

All reagents and solvents were used as received (Sigma-Aldrich) if not stated otherwise. NOL-130 stab initiation mix and preformed, 19 mg graphite-blended l,3,5-trinitro-l,3,5-triazacyclohexane (RDX) pellets were purchased from Day Zimmerman (DZI). Samples prepared for LC-MS analysis were dissolved in ammonium hydroxide and run utilizing a Phenomenex Gemini C6-Phenyl column (4.6 mm X 150 mm) and a mobile phase of 20 mM ammonium acetate in water pH 7.02 at 0.75 ml,-min The HPLC analysis is done using... 

FIGURE 1.25 HPLC determination of impurities in a levothyroxin (L-T4) formulation. Experimental conditions Column, Chiralpak QN-AX (150 rum x 4 rum ID) mobile phase, acetonitrile-50 mM ammonium acetate (60 40, v/v) (pHa 4.5) flow rate, 0.7 mLmiu UV detection, 240 nm temperature, 25 C. Sample, T4-200 tablets (Uni-Pharma, Greece) containing 0.2 mg L-T4 sodium per tablet the tablet was pulverized, suspended in methanol-10 mM sodium hydroxide (1 1 v/v) and after ultrasonication for 5 min the residues were removed by filtration. An aliquot of 10 xL of the filtrate was directly injected. (Reproduced from H. Gika et al., J. Chromatogr. B, 800 193 (2004). With permission.)... 

The addition of buffering salts to the mobile phase often improves chromatographic separation, provides a stable pH during separation, and reduces problems associated with column disturbances produced by highly variable samples. These salts are usually volatile (examples are ammonium formate, ammonium acetate, and i-ethylammonium hydroxide) and the concentrations used are usually less than 10 mM. With the advent of orthogonal interfaces for ESI and APCI, the absolute requirement for volatile salts has disappeared. However, the prolonged use of nonvolatile salts is not recommended as the accumulation of salts in the spray chamber of the MS reduces sensitivity and increases maintenance requirements. 

Chemical/Physical. The estimated hydrolysis half-life of acetonitrile at 25 °C and pH 7 is >150,000 yr (Ellington et al., 1988). No measurable hydrolysis was observed at 85 °C at pH values 3.26 and 6.99. At 66.0 °C (pH 10.42) and 85.5 °C (pH 10.13), the hydrolysis half-lives based on first-order rate constants were 32.2 and 5.5 d, respectively (Ellington et al., 1987). The presence of hydroxide or hydronium ions facilitates hydrolysis transforming acetonitrile to the intermediate acetamide which undergoes hydrolysis forming acetic acid and ammonia (Kollig, 1993). Acetic acid and ammonia formed react quickly forming ammonium acetate. 

Figure 1 Separation of impurities A, B, and C from the peak of interest (P) using seven different HPLC systems. Reprinted from [14], copyright 2004, with permission from Elsevier. (For each system the column temperature is 30°C, the detector is UV 254 nm and the gradient is a 60-min gradient from 5% to 95% organic modifier. Ml column 250 X 4.6 mm i.d. 5 pm Kromasil C4, mobile-phase acetonitrile/0.1% trifluoroacetic acid [pH 1.9] M2 column 100X4.6 mm i.d. 5 pm Luna phenyl-hexyl, mobile-phase acetonitrile/0.1% acetic acid adjusted to pH 3.5 with ammonium hydroxide M3 column 100 X 4.6 mm i.d. 5 pm Luna phenyl-hexyl, mobile-phase acetonitrile/10 mM ammonium acetate [pH 7.0] M4 column 100 X 4.6 mm i.d. 5 pm Luna phenyl-hexyl, mobile phase THF/10 mM ammonium acetate adjusted to pH 5.0 with glacial acetic acid M5 column 150 X 4.6 mm i.d. 3 pm Spherisorb ODSl, mobile-phase methanol/10 mM ammonium acetate [pH 7.0] M6 column 150 X 4.6 mm i.d. 5 pm Monitor Cl8, mobile-phase methanol/0.1% acetic acid adjusted to pH 3.5 with ammonium acetate M8 column 100 X 4.6 mm i.d. 4 pm YMC J Sphere ODS H80, mobile-phase acetonitrile/0.1% formic acid [pH 2.1] [M7 is a variation on the M8 gradient and is not shown].)...

Some commonly used buffers, such as sodium and potassium phosphate, are incompatible with ELSD, but there are ready alternatives. For example, ammonium acetate has similar buffering properties to potassium phosphate, and ammonium carbonate, ammonium formate, pyridinium acetate, and pyridinium formate are options for different pH ranges. Typical mobile phase modifiers that do not meet the volatility criteria can be replaced by a wide variety of more volatile alternates. For example, phosphoric acid, commonly used as an acid modifier fo control pH and ionization, can be replaced by trifluoroacetic acid other acids that are sufficiently volatile for use with FLSD include, acetic, carbonic, and formic acids. Triethylamine, commonly used as a base modifier, is compatible with FLSD other base modifiers that can be used are ethylamine, methylamine, and ammonium hydroxide [78]. 

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