SOLUBILITY AND PH OF PROTEIN SOLUTIONS 10% type Solubility pH Corn steep liquor Slight sediment 3.98 EZ Case M Soluble 7.12 Hydrolyzed casein Stable suspension 5.02 Liquid amino acids Soluble 5.58 Nu-Lure Soluble 3.82 Nu-Lure in 0.2 M fructose Soluble 3.82 Nu-Lure + 5% sodium tetraborate
Soluble 8.01 Nu-Lure in 0.2 M sucrose Soluble 3.80 Nu-Lure in 0.2 M sucrose + 0.05 M valine Soluble 3.79 Nu-Lure plus 0.05 M valine Soluble 3.78 Pepticase Soluble 6.96 Prolisse Thick suspension 6.96 Sodium caseinate Not soluble 6.22 Solulys Slight sediment 3.98 Soy protein acid hydrolysate Some sediment 5.70 Torula yeast Not soluble 6.31 Whey Some sediment 5.38 Yeast hydrolysate enzymatic Some sediment 5.60 TABLE 2.
* Aluminum borate: alum (15%) and sodium tetraborate
The buffer solutions at were prepared from; HCl (0.1 M), KCl (1.0 M, pH 1-2), CH3COOH (1.0M) and NaCH3COO (1 .0 M, pH 3-6), oxalic acidand sodium oxalate (0.1M, pH 2-5), citric acid (1.0M) and sodium citrate (1.0 M, pH 2-5), boric acid (0.1 M) and sodium tetraborate
(0.1M, pH 4 -9) and sodium bicarbonate (0.1M) and sodium carbonate (0.1M, pH 8-10).
To stabilize the enzymes, pH should be 7-9; water content (less than 60%), calcium chloride (0.2%), sodium tetraborate
(1-2%), propylene glycol (5-10%), sodium formate (1-2%), sodium citrate (3-5%) and monoethanol amine (1%)
Gum Arabic (from acacia tree) of approximate molecular weight 250,000 (Product No.G-9752), primaquine phosphate, sorbitan sesquioleate, borax (sodium tetraborate
decahydrate) and sodium m-periodate were purchased from Sigma, USA.
System 2 was essentially the same as system 1 except that a CarboPack PA1 column (4 x 250 mm; Dionex) was used and isocratic separation was performed with 14 mmol/L sodium tetraborate
at a flow of 1.5 mL/min.
Buffer solution pH 1-10 at unit interval were prepared as: hydrochloric acid (0.1M) and potassium chloride (0.1M) pH 1-2; acetic acid (0.1M) and sodium acetate (0.1M) pH 3-6; boric acid (0.1M) and sodium tetraborate
(0.1M) pH 8-9; sodium bicarbonate, sodium carbonate pH 10 and phosphoric acid (0.1M) and sodium dihydrogen phosphate(0.1M) pH 2-7.The wastewater samples were obtained from common tannery treatment plant of tannery complex and goldsmith factories (Karachi, Pakistan).
Buffer with 10 mmol/L sodium tetraborate
, 10 mmol/L sodium monophosphate (Sigma Chemical Co.), pH 8.0, with 100 mL/L acetonitrile (analytical grade, Fisher Scientific) was filtered with a 0.45-[micro]m filter; running voltage was +18 kV.