Borate -, potassium

Merino-Merino et al. [32] used the OPA reagent (o-phthaldehyde condensed with 2-mercaptoethanol) to separate penicillamine enantiomers after their derivatization. Racemic and (/q-penicillamine were dissolved in aqueous 0.5 M NaOH, and treated with the derivatizing solution (methanolic o-phthaldehyde and 2-mercaptoethanol in 0.4 M potassium borate buffer solution of pH 10). The reaction mixture was set aside for 2 min at room temperture, whereupon a portion of solution was analyzed by HPLC. The method used a Cyclobond column (25 cm x 4.6 mm) maintained at 5 °C, a mobile phase of ethanol/1% triethylammonium acetate (1 1 pH 4.5) eluted at... 

Reagents OPA-reagent 5 mM o-phtalic dialdehyde, 0.020 M N-acetylcysteine, 7 mM sodium lauroylsarcosinate, 0.5 M potassium borate, pH 10 acidifying reagent 0.067 M sodium citrate, pH 2.0. 

OPA 97% (Aldrich) prepared by dissolving 20 mg of the salt in 0.5 ml methanol. Add to this solution 3 ml of the potassium borate buffer and 2 ml H20, followed by 30 pi mercaptoethanol. This reagent is stable for 1 week when stored in the dark. 

Figure J. Sulfuric acid hydrolysates of holocelluloses of sprucewood and beechwood. Separation on Durrum DA-X4 (column 0.4 X 30 cm) with 0.49M potassium-borate buffer at pH 9.2 and 60°C (16) detection with 2, 2-bicinchoninate (17).

Although B(0H)3 and B(OH)4 are monomeric in dilute solutions, at concentrations above about O.lmolL, condensed borate species that are often referred to as polyborates form. Titration of a boric acid solution with one molar equivalent of a strong base leads to formation of the tetrahydroxyborate anion, B(OH)4, as the principal species in solution. Mixtures of boric acid and its conjugate base, the tetrahydroxyborate anion, form what appears to be a classical buffer system where the pH is determined primarily by the acid salt ratio with [H+] = K[B(OH)3]/[B(OH)4 ]. This relationship is approximately correct for sodium and potassium borates with a sodium boron ratio of 1 2. Here the B(0H)3 B(0H)4 ratio equals one, and the solution pH remains near 9 over a wide range. However, for borate solutions with pH values significantly above or below 9,... 

B6K2O10 (s) K2O 3B2O3 (s) Potassium Borate B6K2O-10 (s) K2O 3B2O3 (s)... 

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