Ammonium acetate carbamate

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... 

The PO mode is a specific elution condition in HPLC enantiomer separation, which has received remarkable popularity especially for macrocyclic antibiotics CSPs and cyclodextrin-based CSPs. It is also applicable and often preferred over RP and NP modes for the separation of chiral acids on the cinchonan carbamate-type CSPs. The beneficial characteristics of the PO mode may arise from (i) the offset of nonspecific hydrophobic interactions, (ii) the faster elution speed, (iii) sometimes enhanced enan-tioselectivities, (iv) favorable peak shapes due to improved diffusive mass transfer in the intraparticulate pores, and last but not least, (v) less stress to the column, which may extend the column lifetime. Hence, it is rational to start separation attempts with such elution conditions. Typical eluents are composed of methanol, acetonitrile (ACN), or methanol-acetonitrile mixtures and to account for the ion-exchange retention mechanism the addition of a competitor acid that acts also as counterion (e.g., 0.5-2% glacial acetic acid or 0.1% formic acid) is required. A good choice for initial tests turned out to be a mobile phase being composed of methanol-glacial acetic acid-ammonium acetate (98 2 0.5 v/v/w). 

In simple experiments, particulate silica-supported CSPs having various cin-chonan carbamate selectors immobilized to the surface were employed in an enantioselective liquid-solid batch extraction process for the enantioselective enrichment of the weak binding enantiomer of amino acid derivatives in the liquid phase (methanol-0.1M ammonium acetate buffer pH 6) and the stronger binding enantiomer in the solid phase [64]. For example, when a CSP with the 6>-9-(tcrt-butylcarbamoyl)-6 -neopentoxy-cinchonidine selector was employed at an about 10-fold molar excess as related to the DNB-Leu selectand which was dissolved as a racemate in the liquid phase specified earlier, an enantiomeric excess of 89% could be measured in the supernatant after a single extraction step (i.e., a single equilibration step). This corresponds to an enantioselectivity factor of 17.7 (a-value in HPLC amounted to 31.7). Such a batch extraction method could serve as enrichment technique in hybrid processes such as in combination with, for example, crystallization. In the presented study, it was however used for screening of the enantiomer separation power of a series of CSPs. 

Aryl-, aryloxy- and arylthiocarboxylic acids, N-derivatized amino acids Quinine and quinidine carbamates Methanol—0.1 M 194 ammonium acetate, pH 6.0 (80 20)... 

Carbamates Reversed-phase-C18, acetonitrile-water-ammonium acetate MS (thermospray) 0.025-1 ppm 121... 

Urethane.—This ethyl ester of carbamic acid is known as urethane. Ammonium carbamate is the intermediate product in the relationship between ammonium carbonate and carbamide, analogous to that between ammonium acetate and acetamide. 

Ammonium acetate Ammonium bicarbonate Ammonium carbamate Ammonium carbonate Ammonium chloride Ammonium hydroxide Ammonium lactate Ammonium phosphate L-Ascorbic acid Bismuth citrate... 

Methyl 5-hydroxy-2-benzimidazole carbamate (MHBC, Figure 7.4), a urinary metabolite of the pesticides carbendazium, benomyl and thiophanate-methyl, has been measured using an ODS-modihed silica analytical column with methanol-aq. ammonium acetate (approximately 60 mmol L , pH 8) (27 + 73) as eluent and ED (PGE, +0.22 V vs Pd). Sample preparation was by a complex procedure involving SPE (SCX-modified silica) of hydrolysed specimens. No internal standard... 

Aminobiphenyl, 4-Aminocarb Aminopyridine, 4-Amiton Amitrole Ammonia Ammonia solutions Ammonium acetate Ammonium benzoate Ammonium bicarbonate Ammonium bisulphite Ammonium carbamate Ammonium carbonate Ammonium chlorate Ammonium chloride Ammonium chromate Ammonium citrate Ammonium dichromate Ammonium fluoride Ammonium hydrogen fluoride Ammonium hydrogen sulfate Ammonium hydroxide Ammonium nitrate Ammonium nitrate fertihzers Ammonium oxalate Ammonium phosphates Ammonium picrate Ammonium sulfamate Ammonium sulfate Ammonium sulfide Ammonium sulfite Ammonium tartrate Amyl acetate... 

In an extremely diverse survey, Bagheri et al. [215] generated a separation for 39 carbamates, triazines, phenylureas, and organophosphoros pesticides using a Cig column (thermospray MS) with a 10/90 ->-90/10 methanol/water (0.1 M ammonium acetate) gradient. Excellent overall resolution between all compounds and... 

Ammonium acetate buffer. Prepjire a 20 % aqueous solution of CH3COONH4 (a.g. to be stored at about 4 °C) and purify the buffer by repeated carbamate/Freon or chloroform extraction (eg., add 0.5 mL of 1 % APDC/DDDC for 100mL of the buffer, and extract three times with 5 mL of Freon or chloroform). 

Digest sample with HNO 3 evaporate to dryness add glacial acetic acid and adjust to pH 3 add ammonium pyrrolidine dlthlo-carbamate and extract with methyl 1sobutyl ketone heat organic organic phase to dryness dissolve residue with HNO3... 

Additional semipermeable membrane—forming polymers are selected from the group consisting of acetaldehyde dimethyl cellulose acetate, cellulose acetate ethyl carbamate, cellulose dimethylamino acetate, semipermeable polyamides, semipermeable polyurethanes, or semipermeable sulfonated polystyrenes. Semipermeable cross-linked selectively permeable polymers formed by coprecipitation of a polyanion and a polycation also can be used for this purpose.22 23 Other polymer materials such as lightly cross-linked polystyrene derivatives, semipermeable cross-linked poly(sodium styrene sulfonate), and semipermeable poly (vinylbenzyltrimethyl ammonium chloride) may be considered.24,25... 

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