Buffer ammonium acetate

Abbreviations. DNB dinitrobenzoyl DNP 2,4-dinitrophenyl DNZ 3,5-dinitrobenzyloxycarbonyl. CSP tert-butyl carbamoylated quinine based buffer ammonium acetate. 

Bile was collected, added with 100 Ezetimibe ketone 50% pL buffer ammonium acetate 0.1 M, pH 4.5 then stored at (-)... 

The activity of the immobilized enzyme bioreactor plays an important role in the quality of the spectra. Immobilized enzyme activity is dependent on pH, temperature, solvents and buffers used for the hydrolysis. Extremes in any one condition can irreversibly destroy the bioreactor activity. Hydrolysis at conditions far from optimal can lead to no-hydrolysis or partial hydrolysis of a peptide, providing limited information on the peptide. In order to successfully employ an immobilized enzyme column on-line with HPLC/thermospray MS, organic modifiers must be kept minimal (less than 30-50%), pH must be between 6.5 and 8.5 and buffer (ammonium acetate) concentration around 0.05-0.1M [12]. 

Buffers Ammonium acetate, ammonium formate, triethylammo-nium acetate (10 mM) Phosphate, citrate, carbonate... 

CZE separation of synthetic dyes has been approached by simple (borate and citrate) and volatile buffers (ammonium acetate) modified by solvents as well as nonaqueous systems (ammonium acetate/acetic acid in MeOH). Environmental applications of CZE methodologies include the analysis of spent dyebaths and wastewater samples and the monitoring of groundwater migration, where eosin was used as a fluorescent tracer (details in Table 31.8). ... 

Sample sequences were generated, started, and completed as with ordinary quantitative LC-MS analyses. Except for the lack of an analytical column, the LC-MS system was configured as a typical LC-MS system for quantitative analyses. The four mobile phase constituents were the most frequently used for ordinary quantitative LC-MS analysis two organic solvents, acetonitrile and methanol, and two buffers, ammonium acetate (50 mM) and formic acid (25 mM). A LC-MS system configured this way can easily be switched between fin-... 

FIGURE 4.14 Mass spectrum of hemoglobin in buffered ammonium acetate at pH 9.5 from 1500 to 4500 mlz- All observed peaks are annotated. The elevated pH stabilizes tetramer signal with the [Q+17H+] + tetramer dominating the spectrum. Holoheterodimer and a are also present. 

Sodium acetate Phosphate buffer Hydrochloric acid Sodium hydroxide Phosphate buffer Acetate buffer Sodium hydroxide Sulfuric acid Phosphate buffer Borate buffer Sodium hydroxide Phosphate buffer Sodium hydroxide Sodium hydroxide Borate buffer Ammonium acetate... 

Since all samples and standards are prepared using the same volume of ammonium acetate buffer, the contribution of this source of iron is accounted for by the calibration curve s reagent blank. 

Cyanoamidines such as (10) are converted into the more useful 2-formyl-A-norsteroids (11) by reduction with lithium in methylamine (buffered with ammonium acetate) followed by hydrolysis on hydrated alumina. This yields a mixture containing approximately 5 parts of the 2j5-aldehyde and 3 parts of the 2a-aldehyde (11). Both aldehydes are smoothly dehydrogenated by 2,3-dichloro-5,6-dicyanobenzoquinone in the presence of acid to the 2-formyl--A-iiorsteroids (12). ... 

For most free amino acids and small peptides, a mixture of alcohol with water is a typical mobile phase composition in the reversed-phase mode for glycopeptide CSPs. For some bifunctional amino acids and most other compounds, however, aqueous buffer is usually necessary to enhance resolution. The types of buffers dictate the retention, efficiency and - to a lesser effect - selectivity of analytes. Tri-ethylammonium acetate and ammonium nitrate are the most effective buffer systems, while sodium citrate is also effective for the separation of profens on vancomycin CSP, and ammonium acetate is the most appropriate for LC/MS applications. 

Buffer solution, concentrated. Dissolve 27.5 g ammonium acetate and 11.0 g hydrated sodium acetate in 100 mL water add 1.0 mL glacial acetic (ethanoic) acid and mix well. 

Fig. 10. HPLC of proteins (commercial samples) on the /V-butyl polyacrylamide coated silica gel column. Sample 20 pi of 5-15 mg/ml protein solution in buffer A. Buffer A 10% methanol, 0.2 mol/1 ammonium acetate, pH 4.5. Buffer B methanol. Gradient 50-min linear, 0-100% B. Flow rate 0.8 ml/min. Peaks (/) — lysozym, (2,3) — insulin, (4,5) — myoglobin [57]...

One of the functions of an LC-MS interface is to remove the mobile phase and this results in buffer molecules being deposited in the interface and/or the source of the mass spectrometer with a consequent reduction in detector performance. Methods involving the use of volatile buffers, such as ammonium acetate, are therefore preferred. 

Reference has been made to the problems associated with the presence of highly involatile analytes. Many buffers used in HPLC are inorganic and thus involatile and these tend to compromise the use of the interface, in particular with respect to snagging of the belt in the tunnel seals. The problem of inorganic buffers is not one confined to the moving-belt interface and, unless post-column extraction is to be used, those developing HPLC methods for use with mass spectrometry are advised to utilize relatively volatile buffers, such as ammonium acetate, if at all possible. 

Involatile inorganic buffers, when used as mobile-phase additives, are the prime canse of blocking of the pinhole. The situation can be alleviated either by replacing them by a more volatile alternative, such as ammonium acetate, or by nsing post-colnmn extraction to separate the analytes from the buffer, with the analytes, dissolved in an appropriate organic solvent, being introduced into the mass spectrometer. 

In many cases, a protonated molecular ion (M - - H)+ is the only ion observed in a thermospray spectrum but if ammonium acetate buffer is used, depending upon the relative proton affinities of the species present, an ammonium adduct (M - - NH4)+ may be the predominant ion. In addition, clusters may be formed with components of the mobile phase. Although the thermospray ionization process involves less energy than conventional Cl, and very little intense fragmentation is usually observed, the presence of ions due to the elimination of small molecules, e.g. water, methanol and ketene, is not unknown. These latter ions are usually of relatively low intensity when compared to the protonated or... 

A buffer soiution must contain both the acid and its conjugate base, so at least two reagents must be added to water to prepare a buffer soiution. An acetate buffer can be prepared, for example, from pure water, concentrated acetic acid, and an acetate salt. The cation contained in the salt should not have acid-base properties of its own, so sodium acetate would be an appropriate choice, but ammonium acetate would not. 

Chromatography on immobilized reactive dyes (1-4 ml) was performed in 10 mM ammonium acetate buffer (pH 4 or 5) and elution followed with a linear 0-1 M NaCl gradient in the same buffer. 

Compounds that were included in the pharmacologic profile of [ H]MDA binding were subjected to reverse-phase HPLC analysis to assess their relative lipophilicity. Briefly, each compound (10 pg) was injected onto a Waters Nova-Pak C18 column and eluted with a linear gradient from 95 percent buffer A 5 percent buffer B to 20 percent buffer A 80 percent buffer B (buffer A=95 percent water, 5 percent acetonitrile, 0.1 percent ammonium acetate buffer B=20 percent water, 80 percent acetonitrile,... 

The determination of acifluorfen in soybean was performed using CE," under the following conditions capillary column (total length 83 cm, 65 cm to the detector, with a 3-mm pathlength, 75-p.m i.d.) absorbance detector, 240 nm capillary oven temperature, 20 °C mnning buffer, 50 mM ammonium acetate buffer (pH, 4.75) applied voltage, 17 kV injection, 0.4 min at 4 mbar migration time, 20 min. 

Figure 11 CE/MS of alfalfa hay fortified with 0.25mgkg of paraquat (upper half) and 0.28mgkg of diquat (lower half). Buffer 50mM ammonium acetate at pH 4.5. Sheath liquid methanol-water-50mM ammonium acetate (5 4 1). Positive ESI...

---