Dtrate buffer

Hb 87 99 Methyl tert-butyl ether/dtrate buffer (pH 5.5), HCN, room temperature... 

Mobile phase MeCN 6.5 mM tetraheplylammonium bromide 100 mM pH 7.0 phosphate buffer 100 mM pH 5.0 dtrate buffer 40 55.2 4.4 0.4 Flow rate 1 Injection volume 20 Detector UV 271... 

Sample preparation Condition a 1 mL Bakerbond C18 SPE cartridge with MeOH and 50 mM pH 5.5 dtrate buffer. 500 p,L Serum -I- 17 p-L 600 p,g/mL sulfamethazine in MeCN water 20 80 + 500 p.L 50 mM pH 5.5 dtrate buffer, vortex, add to the SPE cartridge, wash twice with 50 mM pH 5.5 dtrate buffer, air dry, elute with MeOH. Evaporate the eluate to dryness under a stream of nitrogen at 45°, reconstitute the residue in 250 p.L mobile phase, inject a 10 pL aliquot. 

Peroxidase substrate solution 3,3, 5,5 -tetramethylbenzidine (100 jxl of a 10 mgftnl soluticHi in DMSO) and 7.5 (xl of 6% hydrogen peroxide (freshly prepared from 30% stock solution) in 10 ml of 0.1 M sodium acetate/dtrate buffer pH 6.0 Alkaline phosphatase stopping solution 2 MNaOH... 

A final ex danation of the slow deswelling is that above pH 6.5, the gel must deprotonate by transferring ite protons to hydroxyl ions and buffer spedes. Except at very high pH, hydrox ion concentrations are quite low. Neither citrate nor phosphate buffer can be very hdfrfid. The highest pK for citrate is approximately 6.4, well t low the pKa of the gel amines (7.8). Thus jn oton transfer from amine to dtrate is not favored. Phosphate buffer has pK values... 

Separations based on complex formation The relative retentions for closely similar metal ions often may be enhanced by use of a suitable reagent (such as EDTA) to take advantage of differences in formation constants of the complexes. A classic example is the separation of the lanthanides with a buffered dtrate solution as the eluting agent. Especially effective separations are possible when one metal is converted to an anionic complex while another is present as a cation. Teicher and... 

Important This assay is not compatible with buffers containing carboxylic add groups, such as sodiiun dtrate or 2i7-(2-acetamido)-iminoacetic acid (ADA), because the Biomol Green complex formation is compromised in such buffers. 

Different modified dtrate-based buffers are widely used and commercially available under different names such as Target Retrieval Solution, pH 6 (Dako) and Citra (BioGenex). Detergents could be added and slightly improve the efficiency of the buffer. 

Maximum hydrolytic stability of silica-based reversed-phase packings is obtained at pH values around 4. At pH 2 and pH 8 one may encounter a faster aging of the column, visible through decreased hydrophobic interaction and increased silanophilic interaction. However, the actual rate depends on many different parameters, including the choice of buffer, temperature, and the organic modifier. Columns tend to be mote stable in acetonitrile-based mobile phases than in methanol-based mobile phases, and recent results indicate that dtrate or Tris buffers are preferred over phosphate buffers (32). 

MW 30000 cut-off pre-washed centrifugmg with 2 mL water) while centrifiigiiig at 5000 g for 30-90 min, ityect a 600 [lL aliquot of the ultrafiltrate. (Prepare sucdnate buffer by dissolving 11.8 g succinic add in 980 mL water, ac just pH to 4.0 with 10 M NaOH, make up to 1L. Prepare the dtrate hosphate buffer by dissolving 12.9 g dtric add monohydrate, 10.9 g Na2HP04, 37.2 g disodium EDTA dihydrate, and 29.2 g NaCl in 1 L water.)... 

Various eluent systems have been proposed for HPLC determination of DFAA. In most cases they are combinations of methanol with different buffers such as phosphate, dtrate or acetate. Mopper and Dawson (1986) discussed problems associated with phosphate buffers which often cause clogging of check valves. In our experience acetate buffers present no such problems in routine analysis. 

Surface yield stress was estimated by measuring surface viscosity using a Brookfield viscometer protein solutions of 0.1 wt% in 10 mM dtrate (pH 3-5.5) and phosphate (pH 5.7-8) buffers at 3°C after 5 min. 

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